Humidity and Dew-Point Measurement and

Humidity and Dew-Point Measurement and
Humidity and Dew-Point
Measurement and Calibration
Humidity and Dew-Point Instruments
1
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accreditations
UKAS
At Michell Instruments we understand and endorse the need to
conform to recognized standards for quality and calibration. Our
calibration laboratory maintains full traceability to British (NPL)
and American (NIST) Humidity Standards.
Michell Instruments Limited has been accredited to UKAS (United
Kingdom Accreditation Service) for the calibration of dew-point
hygrometers since 1986 (laboratory number 0179) and our
current dew-point calibration range is -90 to +90°C (-130 to
+194°F). For full details of our measurement capability please see
our Schedule of Accreditation. Our traceability to NIST (National
Institute of Standards & Technology) is over the range -75 to
+20°C (-103 to +68°F).
0179
As a result of the European Accreditation (EA), our UKAS
accreditation carries equal validity in any country which is a
member of the EA.
NVLAP
Michell’s UKAS accreditation is commonly recognized in the
USA as equivalent to NVLAP (National Voluntary Laboratory
Accreditation Program).
ISO 9001:2008
Michell Instruments Limited has been awarded registration to BS
EN ISO 9001:2008.
These prestigious accreditations and registration give Michell
Instruments Limited a unique position within the field of
hygrometry - independently audited and commended by National
Bodies on both quality and calibration.
Q 06284
HAZARDOUS AREA PRODUCTS
Michell Instruments Limited produces, amongst its extensive
range, products specifically designed for use within hazardous
areas or locations. These products use various methods of
protection to impart the safety level required. All such products
are independently assessed and certified to many international
standards, including, but not limited to, ATEX (European), IECEx,
CSA, FM, UL, GOSK-R and GOST-K.
Accreditations and certificates for these products can be
downloaded from the Michell website (www.michell.com) under
the Product Documents/Accreditations section.
The installation and use of products approved for use in
hazardous areas or locations must only be carried out by suitably
trained personnel, and in accordance with the latest national
standards currently in use in that region.
© Michell Instruments 2009-2011
2
Version 3.0
Humidity and Dew-Point Instruments
Michell Instruments
Global Leader for Solutions in Moisture, Humidity and Gas Analysis
Service and Support
Established in 1974, the Michell Instruments Group of
Companies brings more than 35 years of research, design
and state-of-the-art technology to the world of moisture
measurement and control. The current products include:
Michell prides itself with an extensive network of factory
trained application engineers, subsidiaries and distributors
stretching across 56 countries. Service centers and
calibration laboratories are located on three continents
- North America, Europe and Asia. The company, always
aware of the importance of after-sales, offers field
support and exchange programs to maintain continuous
operation at its customers’ facilities.
Products
•
•
•
•
•
•
•
dew-point transmitters
chilled mirror hygrometers
relative humidity (RH) sensors
process moisture analyzers
hydrocarbon dew-point analyzers
moisture in liquid analyzers
oxygen analyzers
Applications
High-precision capacitive moisture transmitters help
customers to measure trace moisture in their process
applications and are the No. 1 choice for manufacturers
of drying systems worldwide. Relative Humidity
transmitters and temperature sensors are widely used
in HVAC applications, weather stations, pharmaceutical
storage and many other processes where controlled
environmental conditions are crucial.
Technology Centers
Michell’s Technology Center of Excellence is in Ely,
UK, where many research projects are carried out in
association with world-famous, and nearby, Cambridge
University. Other R&D facilities are based in Made, The
Netherlands and Lyon, France.
Companies around the world save thousands of euros
using Michell’s humidity calibration systems, incorporating
the Michell reference chilled mirror dew-point
hygrometers. The calibration of portable hygrometers and
relative humidity instruments in-house, reduces downtime and cuts expense.
Manufacturing
Michell Instruments has three manufacturing locations:
Made, The Netherlands, Lyon, France and Ely UK (the
main certified (BS EN ISO 9001:2008) manufacturing
facility). This location also boasts UKAS accreditation,
NIST and NPL, certified calibration traceability, and many
other worldwide approvals including ATEX, FM, UL, CSA
and many more.
Michell offers the high-speed measurement of oxygen in
a range of applications, including combustion optimization
for power stations, controlling levels of CO2 for breweries,
and clean-gas processes, such as silicon wafer production
and pure gas generation.
Users in the natural gas industry and power plants save
millions of euros in repairs and down-time by using the
Condumax II hydrocarbon dew-point analyzers. These
instruments ensure transmission of natural gas quality at
custody transfer and also prevent gas burner failure and
prolong the life of process equipment.
Other analyzers for moisture in hydrocarbon liquids
are available in explosion proof, intrinsically safe, as
well as laboratory versions, and allow the continuous
measurement of the moisture content in a wide range of
hydrocarbon liquids, including transformer oil, hydraulic
oil, petrochemical fractions and pure hydrocarbons.
3
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Contents
Accreditations...............................................................2
DT282..........................................................................45
Michell Instruments......................................................3
Digital Relative Humidity and Temperature Transmitter - Duct
Mount
Contents........................................................................4
DT284..........................................................................47
Product guide................................................................5
Digital Relative Humidity and Temperature Transmitter - Duct
Mount
PCMini52.......................................................................9
WR283.........................................................................49
Digital Relative Humidity and Temperature Mini Probe w/Analog
Output
Digital Relative Humidity and Temperature Transmitter - Remote
Probe for High Temperatures
PCMini70.....................................................................11
WR285.........................................................................51
Digital Relative Humidity Transmitter - Remote Probe for
Pressurized Applications up to 30 bar (3Mpa)
Relative Humidity and Temperature Mini Probe
PC33 & 52....................................................................13
WR293.........................................................................53
Analog Relative Humidity and Temperature Probe
Digital Relative Humidity and Temperature Transmitter - Remote
Probe for High Temperatures
PC62 & 62V..................................................................15
Digital Relative Humidity & Temperature Probe with Digital or
Analog Output
H5000 & 5100.............................................................55
Capacitive Relative Humidity Sensor
PFMini72......................................................................17
H6000 & 6100.............................................................56
Relative Humidity and Temperature Probe
Capacitive Relative Humidity Sensor
PF211..........................................................................19
I7000 & 7400 (Hygrosmart).......................................57
HVAC Relative Humidity Probe
Interchangeable Module for Relative Humidity
SF52.............................................................................21
S503............................................................................59
Dew-Point Transmitter
Relative Humidity Generator for Calibrations
Easidew Transmitter...................................................23
S904............................................................................61
2-Wire Dew-Point Transmitter
Relative Humidity and Temperature Generator for Calibrations
Easidew TX I.S.............................................................25
OptiCal.........................................................................63
ATEX, FM/CSA Certified Dew-Point Transmitter
Relative Humidity and Temperature Generator with built-in
Chilled Mirror Reference
Easidew PRO I.S..........................................................27
Intrinsically Safe Dew-Point Transmitter
Control Kit...................................................................65
Easidew Online............................................................29
For the Calibration of Relative Humidity Sensors
Dew-Point Hygrometer
Accessories..................................................................67
MDM300......................................................................31
Advanced Dew-Point Hygrometer
Applications for Humidity Sensors..............................76
WM33 & 52..................................................................33
A Guide to the Measurement of Humidity...................79
Relative Humidity and Temperature Transmitter, Wall Mount
Notes...........................................................................91
WM261........................................................................35
Digital Relative Humidity & Temperature Transmitter, Wall Mount
WM281........................................................................37
Digital Relative Humidity & Temperature Transmitter, Wall Mount
WM291........................................................................39
Digital Relative Humidity & Temperature Transmitter, Wall Mount
DT269..........................................................................41
Digital Relative Humidity & Temperature Transmitter, Duct Mount
DT722..........................................................................43
Rugged Industrial Relative Humidity and Temperature
Transmitter, Duct Mount
© Michell Instruments 2009-2011
4
Humidity and Dew-Point Instruments
Product guide
Choosing the best product from
this catalog
Chemical tolerance
When moisture levels need to be measured in a gas (or
in air), changes in temperature, the composition of the
gas and the humidity level will all influence the stability
of the measurement. In some cases the gas needs
to be analyzed prior to selection of the right product.
Michell’s H-type capacitive humidity sensors have a
long track record of good performance in various types
of contaminated atmosphere. If you are unsure about
your gas composition, we recommend that you contact
your sales representative or Michell application engineer
to verify the application with our extensive chemical
tolerance database.
In this catalog we offer a wide range of products for a
large number of applications. In order to help you find
the correct product we have grouped the products in
two ways: with product names and colored application
groups.
The structure of the product names are as follows:
PC – probe with a connector to the cable
PF – probe with a fixed cable
RM – room monitoring
Interchangeable module
WM – wall mount
A number of products within our product range offer
a unique interchangeable module, the I7000. Thanks
to this concept there is no need to recalibrate your
instrument. Simply replace the module for a factory
calibrated module. The plug-and-play system guarantees
fast replacement with a short down-time and no
maintenance. Products presented in this catalog that are
equipped with this interchangeable module, are marked
with the interchangeable module symbol.
DT – duct mount
WR – wall-mount transmitter with remote probe on a
cable
DM – for direct measurement with a hand meter
H – capacitive humidity sensors
I – interchangeable sensor module (Hygrosmart)
SF – dew-point instrument based on capacitive sensor
technology
HYGROSMART ®
INTERCHANGEABLE
MODULE
Easidew – dew-point instruments based on ceramic
sensor technology, for low dew points.
Colored application groups
Interchangeable probe
The six color levels you will find as a label on each
product are based on application structure. For example,
complex or accurate applications can be named as
precision manufacturing - this group of applications often
has demands for precise measurement instruments.
Greenhouses, indoor swimming pools and storage of
pharmaceutical products are controlled environments.
Storage of paper, building automation and humidity
control in museums is included in the HVAC category.
The colors used in this catalog can be used as a guide
for choosing the most suitable instrument for your
application.
In order to achieve better specifications, Michell
Instruments has designed some of their products for use
with an interchangeable probe. This interchangeable
probe is resistant to temperatures of up to 200°C. As
with the interchangeable module, the interchangeable
probe has a plug-and-play system that guarantees fast
replacement with almost no down-time or maintenance.
The interchangeable probe can be sent back to the
factory for servicing. Products presented in this catalog
that are equipped with this interchangeable probe, are
marked with the interchangeable probe symbol.
Precision manufacturing
Environmental control
HVAC
HYGROSMART ®
Meteorological
INTERCHANGEABLE
PROBE
Calibration
Sensors
5
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Humidity Sensor Technology
Relative Humidity Sensors
Easidew Advanced Ceramic Moisture
Sensor Technology for direct trace
moisture and dew-point measurements
Michell’s H5000 and H6000 Series are capacitive humidity
sensors providing fast and accurate measurement of
relative humidity in air, gases and other environments.
Michell’s Easidew transmitters and instruments are
rugged, industrial hygrometers for reliable moisture
analysis, from trace levels to ambient air conditions.
They can be used on a wide range of gases, including
hazardous area applications (flammable or explosive
gases), and with many corrosive gases. All Easidew
instruments use Michell’s Advanced Ceramic Moisture
Sensor technology.
The cutting edge Michell Ceramic Sensor is constructed
using state-of-the-art thin and thick film techniques.
Operation of the sensor depends upon the adsorption of
water vapor into a porous non-conducting “sandwich”
between two conductive layers built on top of a base
ceramic substrate. The active sensor layer is very thin
– less than one micron (a millionth of a metre) and the
porous top conductor that allows transmission of water
vapor into the sensor is precisely engineered to nanotechnology standards, thousandths of a millionth of a
metre thick, in order to ensure precise and repeatable
measurement.
Therefore the sensor responds very rapidly to changes
in applied moisture, both when being dried (on process
start-up) and when called into action if there is moisture
ingress into a process. Despite this extreme sensitivity
to changes in moisture content, the Michell Ceramic
Moisture Sensor is incredibly rugged, due to the nature
of its construction. To protect the sensor further against
contaminants and burrs or metal shavings adhering to
the pipework it is housed in a protective HDPE guard that
keeps contaminants out but is porous to water vapor. All
Michell Easidew Ceramic Moisture Sensors give 2°C dew
point or better accuracy and excellent long-term reliability
and stability in process applications.
The H5000 is used to control ambient environments and
is suitable for many applications. It can be used under
repetitive and prolonged conditions of high humidity
(close to saturation). Condensation or wetting do not
alter sensor performance.
The H6000 provides enhanced protection from
contamination and corrosive environments and can be
used in most applications. It can meet the requirements
resulting from difficult operations, such as tile, brick and
pasta drying. It is protected against chemical contents in
air and is very suitable for poultry farms or fruit/vegetable
storage environments.
Key features of the H5000 and H6000 Series sensors are:

Permeable Gold film

Hygroscopic Mono-layer

Base Electrode
Operating principle

Ceramic Substrate
The H5000 and H6000 relative humidity sensors are
polymer film capacitive devices and benefit from
extremely fast response, low hysteresis and high longterm stability.
• Suitable for high humidity levels
• Wide operating temperature range
• Withstands condensation or wetting
Ceramic sensor tile layers
© Michell Instruments 2009-2011
6
Humidity and Dew-Point Instruments
Humidity Sensor Technology
Michell’s relative humidity sensors were originally
developed by the French company Coreci S.A. In 2008,
the Michell Group acquired the technology and the
dedicated team of sensor engineers in Lyon, France
that have developed the product line and achieved an
enviable, world-wide reputation for sensor quality and
performance.
Upper electrode
The maximum upper limit of the operating range is
represented by the following water/air mixing ratios:
H5000: 250g water/Kg dry air, temp +200°C (+392°F)
H6000: 250g water/Kg dry air, temp +200°C (+392°F)
250g/kg dry air corresponds to 95% RH max at 70°C
(158°F) or 21% RH max at 99°C (210°F)

Thin film polymer
Typical response curve

This curve illustrates the large sensitivity range of
the sensor in terms of capacitance (pF) for 0 to
100% RH measurement range. See below for a typical
variation of approximately 86 pF for a 100% RH variation.

Lower electrodes

Glass substrate


Relative Humidity Sensor tile layers

The key to the sensor’s performance is the design and
construction of the super-thin hygroscopic polymer
material that forms the dielectric of the sensor,
sandwiched between two conductive metal electrodes.
The outer electrode is engineered to have a porosity
specific to water vapor and therefore adapts extremely
quickly and reversibly to the prevailing humidity, giving a
large capacitance response and therefore high sensitivity.








The sensors and their components have been specially
designed and manufactured to provide excellent
metrological features while avoiding interference of the
measured environment.


























































 






 









Operating range

Long term measurement stability
Michell’s H5000 and H6000 Series relative humidity
sensors have an extremely wide range of operation for
temperature and relative humidity measurements, making
them suitable for virtually any application.







Under extreme and prolonged conditions of high humidity
(>95% RH), a drift may be observed, but it is reversible
once ambient conditions are restored.











Duration (DAYS):
1
7
Reversible deviation (% RH):
2%
3%



Long-term drift is low for a wide range of temperature
and RH values. Typically, for a 12-month period the drift
is less than 2%, measured at 75% RH and at ambient
room temperature.









The excellent metrological characteristics of the H5000
and H6000 ensure that short- and long-term drift are
minimized.
  




  



7
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Humidity Sensor Technology
Calibration of in-service hygrometers should be verified
on a 6 to 12 months schedule. Under normal operating
conditions, accuracy is excellent, and an adjustment is
normally not necessary. Saturated salt and unsaturated
salt RH reference elements are available for calibration
procedures, as well as more sophisticated automatic
calibrators such as the S503, S904 and OptiCal. Under
normal operating conditions, experience has shown that
the life expectancy of sensors is longer than 10 years.
Cleaning: may be done by immersing the sensor in clean
water and drying naturally in air.
Behaviour in corrosive environments
H6000 hydrophobic layer increases dust protection in high
air flow and in case of frequent wetting.
Influence of air velocity on the measurement
H5000 and H6000 sensing elements require some
elementary precautions in order to prevent the pollution
of the active surface. The H5100 & H6100 cover provides
mechanical protection.
H5000 and H6000 sensors use a synthetic polymer as a
dielectric that is intrinsically resistant to corrosion and
contamination. However, many industrial applications
involve a large number of acid and oxidizing agents, and
the long-term sensor reactions to oxidizing environments
(such as S02) with high RH levels are quite interesting.
The KESTERNICH test is used to simulate the unit
response under these conditions.
In all cases, some form of mechanical protection, such as
a slotted, sintered or polymer guard is recommended. It
is generally not necessary to force fluid circulation due to
the rapid response time of the sensor, however a moving
air or gas flow will aid equilibration times in the process
itself. Fluid flow velocity up to 20m/second will have no
adverse effects on sensors protected by a mechanical
cover.
The test consists of immersing the products in an
aggressive gas. A single testing day corresponds to 1 year
under normal operating conditions, which accelerates
ageing by 365 times. The KESTERNICH test (name of its
inventor) meets the DIN 50.018 KF W 0.2 S standards.
Calibration recommendations
All types of RH generators can be used for short
calibration periods or for tests under 24 hours.
Nevertheless, Stable Saturated Salt Solutions (S.S.S.S.)
are suitable for calibrations and inspection but are not
recommended for long-term tests, especially at high
humidity.
Michell’s H5000 and H6000 sensors have been subjected
to the KESTERNICH test under the supervision of an
external laboratory - Laboratoire Central des Industries
Electriques (L.C.I.E., n0356502 dated 14 July 1991).
A stabilization period of 5-15 minutes is recommended
for relative humidity sensor calibration or other tests,
depending upon the method of RH generation (e.g. a 15
minute period is recommended for S.S.S.S.). However, it
should be noted that the actual stabilization time of some
saturated and unsaturated mixtures can be significantly
longer. Michell can advise on a calibration timing protocol
to suit your exact needs.
The test results showed:
Appearance: slight alteration after 10 years.
Operation: No measurable effect after 10 years.
Condensation and cleaning
Condensation or occasional wetting have no adverse
effects on H Series sensor reliability. H5000 and H6000
revert to their initial metrological features once the liquid
water has been thoroughly eliminated.
H5000: at humidities above 98% RH there is a high risk
of wetting. In this case the sensor will not be damaged,
but 2-3 hours may be necessary before the sensor reverts
to its normal condition.
H6000: wetting could occur in close-to-saturation
operating conditions but in such cases the sensor will not
be seriously damaged and it may take up to 30 minutes
before reverting to its initial measuring conditions.
It is recommended not to touch the surfaces of the
sensor with mechanical devices or your finger. Do not try
to remove particles or deposits as they do not modify the
characteristics of the sensor.
© Michell Instruments 2009-2011
8
Humidity and Dew-Point Instruments
Environmental Control
PCMini52
Digital Relative Humidity and Temperature Mini Probe w/Analog Output
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (10–90% RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
Output signal options
0–1, 0–5, 0–10 V
Supply voltage
14–35 V DC (for 0–5 / 10 V)
4.5–35 V DC (for 0–1 V)
and 14–26 V AC
Operating conditions
The microprocessor control and multi-point calibration gives
the PCMini52 RH probe excellent performance in terms of
accuracy and linearity. The mini probe can provide two linear
analog outputs for temperature and relative humidity, dew
point or absolute humidity.
Operating humidity
Probe, Housing, Storage
5-95% RH (non-condensing)
Operating temperature
Sensing element
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
Mechanical specification
Highlights
• Output can be % RH, calculated absolute humidity, dew
point or wet bulb temperature + temperature
• E
xcellent linearity, (μP) micro processor temperature
compensated
Ingress protection
IP65 (NEMA4 level)
Housing material
Molded polymer or stainless steel (ordering
option)
Dimensions
L=80mm, ø12mm (L=3.15”, ø0.47”)
Weight
10g (0.35oz)
Electrical connections
4 pin, M8 connector
• Low power consumption, fast settling time
Accessories and Spare Parts
• Small size: L = 80mm, ø12mm (L = 3.15”, ø0.47”)
Dimensions
12mm (0.47”) Slotted protection cap, black
A000003
12mm (0.47”) PVDF filter
A000017
12mm (0.47”) PVDF filter with protection cap, black
A000018
12mm (0.47”) Mesh filter with protection cap, black
A000022
12mm (0.47”) Flat SS sintered dust filter
A000023
12mm (0.47”) Arrow 20 μm SS sintered filter
A000028
12mm (0.47”) Connector with 2m (6.5’) cable
A000033
12mm (0.47”) Connector with 5m (16’) cable
A000036
12mm (0.47”) Connector with 10m (33’) cable
A000037
1/2” NPT SS adj fitting for SS probe
A000101
Aluminum mounting flange for ø12.0mm (ø0.47”) SS probes
A000111
ø90mm (3.54") WM weather prot. cap (in combination with
A000111 for ø12mm (0.47") probes)
A000120
ø120mm (4.72") WM weather prot. cap (in combination with
A000111 for ø12mm (0.47") probes)
A000125
12mm (0.47”) Connector without cable (with solder terminals)
A000321
12mm (0.47”) Connector with cable (customer spec length)
A000321XM
12mm (0.47”) Connector with 20m (25.6’) cable
A000322
You can check your hygrometer with the Control Kit HKC which
is based on the principle of non-saturated salt solutions. Refer
to technical data sheet CONTROL KIT
HKC
Issue No: PCMini52_97176_V2_UK_1110
9
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Cable
Brown
Supply voltage V +
White
Output RH, Dew Point or Absolute Humidity
Black
Output temperature
Blue
Common ground
Ordering Example
PCMini52-BASE-4-XX-H-T1-CA-03
Relative humidity and temperature mini probe PCMini52, 0-5 V output, molded polymer body, 0-100% RH signal, -20 to +80ºC (-4 to +176°F) temperature range, no
cable, 12mm slotted protection cap black
Order Codes
PCMini52 - Digital Relative Humidity and Temperature Mini Probe with Analog Output
Feature:
Item
Description
Base Model
PCMINI52-BASE
Base unit
Sig Output
PCMINI52-3
0-10 V
PCMINI52-4
0-5 V
PCMINI52-5
0-1 V
PCMINI52-SX
Stainless steel
PCMINI52-XX
Molded polymer
PCMINI52-H
RH
PCMINI52-D
Calculated dp temp & temp output (Range (Td) -40 to +60ºC (-40 to +140ºF) - Only possible with Temp Signal T1)
PCMINI52-A
Calc absolute humidity (Abs) & temp output (Range Abs from 0-200g/m3 - Only possible with Temp Signal T1)
PCMINI52-W
Calculated wetbulb temp & temp output (Range (Tw) -40 to +60ºC (-40 to +140ºF) - Only possible with Temp Signal T1)
PCMINI52-X
No T output (Not available with 0 - 10 V)
PCMINI52-T1
-20 to +80ºC (-4 to +176°F)
PCMINI52-TX
Other output scaling available on request
PCMINI52-CA
No cable
PCMINI52-CB
12mm (0.47”) Connector with 2m (6.5’) cable
PCMINI52-CC
12mm (0.47”) Connector with 5m (16’) cable
PCMINI52-CD
12mm (0.47”) Connector with 10m (33’) cable
Body
Moist. Sig
Temp. Sig
Cable
Filter
PCMINI52-03
12mm (0.47”) Slotted protection cap, black
PCMINI52-18
12mm (0.47”) PVDF filter with protection cap, black
PCMINI52-22
12mm (0.47”) Mesh filter with protection cap, black
PCMINI52-23
12mm (0.47”) Flat SS sintered dust filter
PCMINI52-28
12mm (0.47”) Arrow 20 μm SS sintered filter
© Michell Instruments 2009-2011
10
Environmental Control
PCMini52
Humidity and Dew-Point Instruments
Environmental Control
PCMini70
Relative Humidity and Temperature Mini Probe
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +85°C (-22 to +185°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
Output signal (RH)
0-1 V
Output signal (T)
3-wire 1/3 DIN Pt100 direct
Supply voltage
5 V DC ±5%
Load resistance
R > 5K Ω
Digital: CMOS compatible
Current consumption
1.5 mA max
Operating conditions
The PCMini70 is a relative humidity mini probe based on the
interchangeable Hygrosmart module.
Operating humidity
Probe, Housing, Storage
0–100% RH
Highlights
Operating temperature
Sensing element
Housing
Storage
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
-40 to +85°C (-40 to +185°F)
• Designed for OEM applications
Mechanical specification
• Based on the interchangeable Hygrosmart module
• Compact housing
Housing material
AISI 316
Dimensions
L=53mm , ø22mm (L=2.08”, ø0.86”)
Filter
AISI 316
Stainless steel mesh
Weight
65g (2.3oz)
Electrical connections
Threaded nipple + nut
Dimensions
Accessories and Spare Parts
Hygrosmart without Pt100 output
I7-0-00-0
Hygrosmart with Pt100 output
I7-0-00-1
SS cap slotted with mesh filter
K1
SS cap slotted with PTFE filter
Z1
Issue No: PCMini70_97177_V2_UK_1110
11
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
PCMini70
Electrical Connections
Cable
Green
Pt100
White
White
Black
0V
- Common ground
Red
+5 V
- Supply Voltage V+
Violet
Out V
- Output RH (Volt)
Yellow
Out F
- Output RH (freq)
Ordering Example
PCMINI70-BASE-1-K1
Relative humidity and temperature mini probe PCMini70, Pt100 direct output and stainless steel cap slotted with mesh filter
Order Codes
PCMini70 - Relative Humidity and Temperature Mini Probe
Feature
Item
Description
Base Model
PCMINI70-BASE
Base unit
Temp
PCMINI70-0
No temperature output
PCMINI70-1
Pt100 direct
PCMINI70-K1
SS cap slotted with mesh filter
PCMINI70-Z1
SS cap slotted with PTFE filter
Filter
© Michell Instruments 2009-2011
12
Environmental Control
Humidity and Dew-Point Instruments
HVAC / Environmental Control
PC33 & 52
Analog Relative Humidity and Temperature Probe
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
PC52: <±2% RH (10–90% RH)
PC33: <±3% RH (30–80% RH)
Accuracy at 23°C (73°F)
Temperature
PC52: ±0.2°C (±0.36°F)
PC33: ±0.3°C (±0.54°F)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
Output signal
4–20 mA, 0–1, 0–5, 0–10 V
Supply voltage
14–30 V DC,
5–30 V DC (0–1 V & mA output)
Operating conditions
The PC series offers a comprehensive range of relative
humidity probes for accurate, stable and repeatable
measurements. Available with analog output signals, the PC
series can be installed in a wide variety of applications.
Operating humidity
Probe, Housing, Storage
5-95% RH
Operating temperature
Probe, Housing
Storage
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
Mechanical specification
Highlights
• L ow cost PC33 with analog output is designed for HVAC
applications
• P
C52 with analog output is designed for accurate
measurement in controlled environments
Ingress protection
IP65 (NEMA 4 level)
Housing material
Molded polymer or stainless steel (ordering
option)
Dimensions
L=130mm, ø19mm (L=5.11”, ø0.74”)
Weight
30g (1.06oz) without cable (molded polymer
version)
Electrical connections
M12
Accessories and Spare Parts
Dimensions
19mm (0.75”) slotted protection cap black
A000002
19mm (0.75”) PVDF filter
A000014
19mm (0.75”) PVDF filter with protection cap black
A000015
19mm (0.75”) Mesh filter with protection cap, black
A000021
19mm (0.75”) Arrow SS sintered filter 5μm / 10μm / 20μm
A000025/26/27
19mm (0.75”) Connector, no cable, with screw terminals
A000030
19mm (0.75”) Connector with cable (customer spec length)
A00030XM
19mm (0.75”) Connector with 2m (6.5’) cable
A000031
19mm (0.75”) Connector with 5m (16’) cable
A000032
19mm (0.75”) Foil filter 2μm with protection cap black
A000040
Oleophobic foil filter 0.7μm with protection cap black
A000042
19mm (0.75”) Foil filter 1.5µm w/protection cap black
A000044
3/4” NPT SS adj. fitting for SS probes
A000100
Al mounting flange for ø19.0mm (ø0.75”) SS probe
A000110
ø90.0mm (ø3.54”) Wall mount weather protection cap
A000120
ø120.0mm (ø4.72”) Wall mount weather protection cap
A000125
Mini flange for ø19.0mm (ø0.75”) molded polymer probe
A000150
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: PC33&52_97178_V2_UK_1110
13
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Voltage output
Cable
4-20 mA output 2-wire
Connector
Cable
Connector
White
Pin 1
Power Supply V +
White
Pin 1
Output RH +
Green
Pin 4
Output RH +
Brown
Pin 3
Output RH -
Yellow
Pin 2
Output temperature +
Green
Pin 4
Output temperature +
Brown
Pin 3
Common ground
Yellow
Pin 2
Output temperature -
Ordering Example
PC33-BASE-4-XX-T3-A-02
Relative humidity and temperature probe PC33, 0-5 V output, molded polymer body, temperature range 0 to +50ºC, no cable, 19mm slotted protection cap
Order Codes
PC33 - Analog Relative Humidity and Temperature Probe - with 1pt
calibration
PC52 - Analog Relative Humidity and Temperature Probe - with 2pt
calibration
Feature
Description
Feature
Item
Description
PC33-BASE
Base unit
Base
Model
PC52-BASE
Base unit
PC33-2
4-20 mA
PC52-2
4-20 mA
PC33-3
0-10 V
PC52-3
0-10 V
PC33-4
0-5 V
PC52-4
0-5 V
PC33-5
0-1 V
PC52-5
0-1 V
PC33-SX
Stainless steel
PC52-SX
Stainless steel
PC33-XX
Molded polymer
PC52-XX
Molded polymer
PC33-TX
Other output scaling available on request
PC52-TX
Other output scaling available on request
PC33-T1
-20 to +80ºC (-4 to +176ºF)
PC52-T1
-20 to +80ºC (-4 to +176ºF)
PC33-T3
0 to +50ºC (+32 to +122ºF)
PC52-T3
0 to +50ºC (+32 to +122ºF)
PC33-X
No T output RH only
PC52-X
No T output RH only
PC33-A
No cable
PC52-A
No cable
PC33-B
19mm (0.75”) Connector, no cable, with screw
terminals
PC52-B
19mm (0.75”) Connector, no cable, with screw
terminals
PC33-C
19mm (0.75”) Connector with 2m (6.5’) cable
PC52-C
19mm (0.75”) Connector with 2m (6.5’) cable
PC33-D
19mm (0.75”) Connector with 5m (16’) cable
PC52-D
19mm (0.75”) Connector with 5m (16’) cable
PC33-02
19mm (0.75”) slotted protection cap black
PC52-02
19mm (0.75”) slotted protection cap black
PC33-15
19mm (0.75”) PVDF filter with protection cap black
PC52-15
19mm (0.75”) PVDF filter with protection cap black
PC33-21
19mm (0.75”) Mesh filter with protection cap, black
PC52-21
19mm (0.75”) Mesh filter with protection cap, black
PC33-25
19mm (0.75”) Arrow SS sintered filter 5μm
PC52-25
19mm (0.75”) Arrow SS sintered filter 5μm
PC33-26
19mm (0.75”) Arrow SS sintered filter 10μm
PC52-26
19mm (0.75”) Arrow SS sintered filter 10μm
PC33-27
19mm (0.75”) Arrow SS sintered filter 20μm
PC52-27
19mm (0.75”) Arrow SS sintered filter 20μm
PC33-40
19mm (0.75”) Foil filter 2μm with protection cap
black
PC52-40
19mm (0.75”) Foil filter 2μm with protection cap
black
PC33-42
Oleophobic foil filter 0.7μm with protection cap black
PC52-42
Oleophobic foil filter 0.7μm with protection cap black
PC33-44
19mm (0.75”) Foil filter 1.5µm w/protection cap
black
PC52-44
19mm (0.75”) Foil filter 1.5µm w/protection cap
black
Base
Model
Sig
Output
Body
Temp
Cable
Filter
Item
© Michell Instruments 2009-2011
Sig
Output
Body
Temp
Cable
Filter
14
HVAC / Environmental Control
PC33 & 52
Humidity and Dew-Point Instruments
Environmental Control / Precision Manufacturing
PC62 & 62V
Digital Relative Humidity & Temperature Probe with Digital or Analog Output
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (10–90% RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
Output signal
0–1, 0–5, 0–10 V, RS232, RS485
Supply voltage
14–30 V DC, 5–30 V DC (0–1 V & mA output)
Operating conditions
The PC series offers a comprehensive range of relative
humidity probes for accurate, stable and repeatable
measurements. Available with analog or digital output
signals, the PC series can be installed in a wide variety of
applications.
Operating humidity
Probe, Housing, Storage
5-95% RH
Operating temperature
Probe, Housing
Storage
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
Mechanical specification
Highlights
• P
C62 is designed for high accurate measurements in
precision manufacturing applications
Ingress protection
IP65 (NEMA 4 level)
Housing material
Molded polymer or stainless steel (ordering
option)
Dimensions
L=130mm, ø19mm ( L=5.11”, ø0.74”)
Weight
30g (1.06oz) (molded polymer) without cable
Electrical connections
M12
• Digital or analog output possible on the PC62
• P
C62 available with calculated absolute humidity, dew
point or wet bulb temperature output
Accessories and Spare Parts
Dimensions
19mm (0.75”) Slotted protection cap black
A000002
19mm (0.75”) PVDF filter
A000014
19mm (0.75”) PVDF filter with protection cap black
A000015
19mm (0.75”) Mesh filter with protection cap black
A000021
19mm (0.75”) Arrow SS sintered filter 5μm / 10μm / 20μm
A000025/26/27
19mm (0.75”) Connector, no cable, with screw terminals
A000030
19mm (0.75”) Connector, with cable (customer spec
length)
A000030XM
19mm (0.75”) Connector with 2m (6.5’) cable
A000031
19mm (0.75”) Connector with 5m (16’) cable
A000032
19mm (0.75”) Foil filter 2μm with protection cap black
A000040
Oleophobic foil filter 0.7μm with protection cap black
A000042
19mm (0.75”) Foil filter 1.5µm w/protection cap black
A000044
3/4” NPT SS adj. fitting for SS probes
A000100
Al mounting flange for ø19.0mm (ø0.75”) SS probe
A000110
Mini flange for ø19.0mm (ø0.75”) molded polymer probe
A000150
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
Control Kit HKC
Issue No: PC62&62V_97209_V2_UK_1110
15
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Voltage output
Cable
Connector
Cable
Connector
RS232
RS485
White
Pin 1
Power Supply V +
White
Pin 1
Power supply V +
Power Supply V +
Green
Pin 4
Output RH +
Green
Pin 4
TX
TX/RX +
Yellow
Pin 2
Output temperature +
Yellow
Pin 2
RX
RX/TX -
Brown
Pin 3
Common ground
Brown
Pin 3
Ground
Ground
Ordering Example
PC62V-BASE-4-XX-T1-TD-CA-02
Relative humidity and temperature probe PC62V, 0-5 V output, molded polymer, temp range -20 to +80ºC (-4 to +176°F) with calculated dew-point temperature and
temperature output, no cable, 19mm slotted protection cap, black
Order Codes
PC62 - Digital Relative Humidity & Temperature Probe with 2%
accuracy and RS232 or RS485 output
PC62V - Digital Relative Humidity and Temperature Probe with 2%
accuracy and voltage output
Feature
Description
Feature
Item
Description
Base
Model
PC62V-BASE
Base unit
PC62V-3
0-10 V
PC62V-4
0-5 V
PC62V-5
0-1 V
PC62V-SX
Stainless steel
PC62V-XX
Molded polymer
PC62V-T1
-20 to +80ºC (-4 to +176°F)
PC62V-TX
Other output scaling available on request
PC62V-RH
RH
PC62V-TA
Abs 0-200g/m3, T= -20 to +80ºC, Calc range
output (Calculated absolute humidity and temp
output - only available with -20 to +80ºC (-4 to
+176ºF) default range)
PC62V-TD
Td -40 to +60ºC T= -20 to +80ºC Calc range
output (Calculated dew-point temp and temp
output - only available with -20 to +80ºC (-4 to
+176ºF) default range)
PC62V-TW
Tw -40 to +60ºC Calc Range output (Calculated
wetbulb temp and temp volt output - only
available with -20 to +80ºC (-4 to +176ºF)
default range)
Item
Base Model
PC62-BASE
Base unit
Sig Output
PC62-0
RS232
PC62-1
RS485
PC62-SX
Stainless steel
PC62-XX
Molded polymer
PC62-TC
Digital output in ºC
PC62-TF
Digital output in ºF
PC62-CA
No cable
PC62-CB
19mm (0.75”) Connector, no cable, with screw
terminals
PC62-CC
19mm (0.75”) Connector with 2m (6.5’) cable
PC62-CD
19mm (0.75”) Connector with 5m (16’) cable
PC62-02
19mm (0.75”) slotted protection cap black
PC62-15
19mm (0.75”) PVDF filter with protection cap
black
PC62-21
19mm (0.75”) Mesh filter with protection cap,
black
PC62-25
19mm (0.75”) Arrow SS sintered filter 5μm
PC62-26
19mm (0.75”) Arrow SS sintered filter 10μm
PC62-27
19mm (0.75”) Arrow SS sintered filter 20μm
PC62V-CA
No cable
PC62-40
19mm (0.75”) Foil filter 2μm with protection cap
black
PC62V-CB
19mm (0.75”) Connector, no cable, with screw
terminals
PC62-42
Oleophobic foil filter 0.7μm with protection cap
black
PC62V-CC
19mm (0.75”) Connector with 2m (6.5’) cable
19mm (0.75”) Foil filter 1.5µm w/protection cap
black
PC62V-CD
19mm (0.75”) Connector with 5m (16’) cable
PC62-44
PC62V-02
19mm (0.75”) slotted protection cap black
PC62V-15
19mm (0.75”) PVDF filter with protection cap
black
PC62V-21
19mm (0.75”) Mesh filter with protection cap,
black
PC62V-25
19mm (0.75”) Arrow SS sintered filter 5μm
PC62V-26
19mm (0.75”) Arrow SS sintered filter 10μm
PC62V-27
19mm (0.75”) Arrow SS sintered filter 20μm
PC62V-40
19mm (0.75”) Foil filter 2μm with protection cap
black
PC62V-42
Oleophobic foil filter 0.7μm with protection cap
black
PC62V-44
19mm (0.75”) Foil filter 1.5µm w/protection cap
black
Body
Temp
Cable
Filter
© Michell Instruments 2009-2011
Sig
Output
Body
Temp
Moist.
Sig
Cable
Filter
16
Environmental Control / Precision Manufacturing
PC62 & 62V
Humidity and Dew-Point Instruments
Meteorological
PFMini72
Relative Humidity and Temperature Probe
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
Output signal (RH)
0–1 V
Output signal (T)
0–1 V or
3-wire 1/3 DIN Pt100 direct
Supply voltage
5.5–32 V DC
Current consumption
2 mA max
Operating conditions
PFMini72 relative humidity probes are equipped with
the Hygrosmart relative humidity sensor/converter. This
interchangeable module has miniaturized electronics and
does not require re-calibration.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-20 to +80°C (-4 to +176°F)
-20 to +80°C (-4 to +176°F)
-40 to +85°C (-40 to +185°F)
Mechanical specification
Highlights
Ingress protection
IP65 (NEMA 4 level)
• Designed for meteorological applications
Housing material
INOX 316L
• Based on the interchangeable Hygrosmart module
Dimensions
L=92mm, ø18mm (L=3.62”, ø0.70”)
Weight
150g (5.29oz)
Electrical connections
4- or 6-wire output cable, length 2m (6.5’)
Dimensions
Accessories and Spare Parts
Mounting clip
2510367
Hygrosmart without Pt100 output
I7-0-00-0
Hygrosmart with Pt100 output
I7-0-00-1
SS cap slotted with mesh filter
K1
SS cap slotted with PTFE filter
Z1
Issue No: PFMini72_97179_V2_UK_1110
17
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
4 wire cable
6 wire cable
White
Output RH +
White
Output RH +
Black
Common ground
Black
Common ground
Red
Power supply V+
Red
Power supply V+
Blue
Output temperature +
Blue
Pt100
Yellow
Green
Ordering Example
PFMINI72-BASE-1-B1-2-K1
Relative humidity and temperature mini probe PFMini72, Pt100 direct output, stainless steel body, 2m (6.5’) cable, stainless steel slotted cap with mesh filter
Order Codes
PFMini72 - Relative Humidity and Temperature Probe
Feature
Item
Description
Base Model
PCMINI72-BASE
Base unit
Temp
PCMINI70-0
No temperature output
PCMINI70-1
Pt100 direct
PCMINI70-B
0-1 V (-20 to +80ºC (-4 to +176ºF) range)
Body
PFMINI72-B1
Stainless Steel
Cable
PFMINI72-2
2m (6.5’)
Filter
PCMINI70-K1
SS cap slotted with mesh filter
PCMINI70-Z1
SS cap slotted with PTFE filter
© Michell Instruments 2009-2011
18
Meteorological
PFMini72
Humidity and Dew-Point Instruments
HVAC Relative Humidity Probe
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +70°C (-22 to +158°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95 % RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step
change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
PF211 relative humidity probes are equipped with the
Hygrosmart relative humidity sensor/converter. This
interchangeable module has miniaturized electronics and
does not require re-calibration.
Output signal (RH)
4–20 mA, 0–10 V
Output signal (T)
3-wire 1/3 DIN Pt100 direct
Supply voltage
10–32 V DC for 4–20 mA output
15–32 V DC for 0–10 V output
24 V AC ±10% (PF211B)
Load resistance
Output 4–20 mA: Rload < (Uv-9)/0.02
Output 0–10 V: R > 1K Ω
Current consumption
20 mA max
Operating conditions
Highlights
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe, Housing, Storage
-30 to +70°C (-22 to +158°F)
Mechanical specification
• D
esigned for HVAC and Environmental Control
applications
• Based on the interchangeable Hygrosmart module
Ingress protection
IP54
Housing material
ABS
Dimensions
L=175mm, ø19mm (L=6.89”, ø0.75”)
Weight
184g (6.49oz)
Electrical connections
5 or 6-wire output cable, 3m (9.8’)
Dimensions
Accessories and Spare Parts




HVAC / Environmental Control
PF211


Mounting clip
2510387
Molded polymer fitting
3401135
Fixing collar
3420085
SS sintered filter
H4
ABS cap slotted with PTFE filter, white
Z2
Hygrosmart with Pt100 output (RH = 0.2-1 V)
I7-4-00-1
Hygrosmart with Pt100 output (RH = 0-1 V)
I7-0-00-1
Issue No: PF211_97180_V2_UK_1110
19
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
PF 211-A: 4-20 mA output 2-wire
PF 211-B: V output (0-10 V)
Cable
Connector
Cable
Connector
Red
Output RH +
Red
Power supply V +
Blue
Output RH -
Black
Common ground
Blue
Output RH +
White
Pt100
White
Yellow
Pt100
Green
Yellow
Green
Ordering Example
PF211-BASE-A-C-Z2
Relative humidity probe PF211, output signal 4-20 mA , 3m (9.8’) cable, ABS cap slotted with PTFE filter, white
Order Codes
PF211 - HVAC Relative Humidity Probe
Feature
Item
Description
Base Model
PF211-BASE
Base unit
Sig Output
PF211-A
4-20 mA output 2-wire
PF211-B
0-10 V output 3-wire
PF211-C
3m (9.8’)
PF211-D
5m (16’)
PF211-E
7m (23')
PF211-F
10m (33')
PF211-G
15m (49')
PF211-Z2
ABS cap slotted with PTFE filter, white
PF211-H4
SS sintered filter
Cable
Filter
© Michell Instruments 2009-2011
20
HVAC / Environmental Control
PF211
Humidity and Dew-Point Instruments
Precision Manufacturing
SF52
Dew-Point Transmitter
Technical Specifications
Performance
Measurement range (dew
point)
-40 to +60°C (-40 to +140°F), dew-point
temperature
Measurement range (absolute
humidity)
0 to 200 g/m3 (0 to 87.4 gr/ft3)
Accuracy (dew point)
<±2°C (-40 to +60°C)
(<±3.6°F (-40 to +140°F))
Accuracy (absolute humidity)
0.4 to 3 g/m3 (0.175 to 1.311 gr/ft3) on
value of absolute humidity
Stability
<1°C / year (<1.8°F / year)
Response time
<10 sec typical (for 90% of the step
change)
Electrical output/input
Output signal
0–1, 0–5, 0–10 V or 4–20 mA
Supply voltage
8-30 V DC (14-30 V DC for 0–10 V output)
Current consumption
9 mA + load current
Supply voltage influence
±0.005 % RH/V
Operating conditions
The SF52 dew-point transmitter from Michell Instruments can
provide 4–20 mA or voltage signal for either dew point or
absolute humidity with excellent accuracy and linearity. The
robust housing, together with an operating pressure of up to
20 barg (300 psig), makes the SF52 ideal for many dew-point
and moisture measurement applications.
Highlights
Operating humidity
Probe, Housing, Storage
0–95% RH (non-condensing)
Operating temperature
Probe, Housing
Storage
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
Operating pressure
20 barg (300 psig) maximum
Temperature coefficient
Temperature compensated across operating
temperature range
Mechanical specification
• Designed for OEM applications
• Dew-point or absolute humidity output
• Flush fitting filter disc for minimal flow disturbance
• Excellent linearity and temperature compensation
Ingress protection
IP65 (NEMA 4 level)
Housing material
Nickel-coated brass
Dimensions
L=85mm, ø24mm (L=3.34”, ø0.94”) (max)
Filter
HDPE front filter
Weight
320g (11.29oz)
Mechanical connections
G ½” BSP (DIN ISO 228) or ½” NPT
Cable
2m (6.5’)
Dimensions
Accessories and Spare Parts
HDPE filter
A000019
Bonded seal, (DIN ISO 228) G½” (BSP)
A000340
Sample block without filter
A000350
Sample block with filter
A000351
Issue No: SF52_97181_V2_UK_1110
21
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Cable
Voltage output/mA output
White
Power supply V+
Green
Output Td+
Brown
Common ground
load max 500 Ω
Ordering Example
SF52-BASE-4-X-T1-N
Dew-point transmitter SF52, 0-5 V output, Td ºC/ºF dp signal -40 to +60ºC (-40 to +140ºF), temperature range -20 to +80ºC (-4 to +176ºF), 1/2” NPT pressure port
Order Codes
SF52 - Dew-Point Transmitter
Feature
Item
Description
Base Model
SF52-BASE
Base unit
Sig Output
SF52-2
4-20 mA
SF52-3
0-10 V
SF52-4
0-5 V
SF52-5
0-1 V
SF52-S
g/m3
SF52-X
Td ºC/ºF dp -40 to +60ºC (-40 to +140ºF)
Temp
SF52-T1
-20 to +80ºC (-4 to +176ºF)
Mount
SF52-B
1/2" BSP thread
SF52-N
1/2" NPT thread
Moist. Sig
© Michell Instruments 2009-2011
22
Precision Manufacturing
SF52
Humidity and Dew-Point Instruments
Precision Manufacturing
Easidew Transmitter
2-Wire Dew-Point Transmitter
Technical Specifications
Performance
Measurement range (dp)
-100 to +20°C (-148 to +68°F) dew point
Accuracy (dp)
±2°C (±3.6°F) dew point
Response time
5 mins to T95 (dry to wet)
Repeatability
0.5°C (0.9°F) dew point
Electrical output/input
Output signal
4-20 mA (2-wire connection, current source)
User configurable over range
Output
Dew point, moisture content for ppmV
Output range
Dew point: -100 to +20°C (-148 to +68°F)
Moisture content in gas: 0-3000 ppmV
Supply voltage
User configurable over range
Load resistance
Max 250 Ω @ 12 V (500 Ω @ 24 V)
Current consumption
20 mA max
Supply voltage influence
±0.005% RH/V
Operating conditions
The Easidew Transmitter is designed for ease of use,
incorporating all the features needed to make installation
and operation as simple as possible. For the first time, dewpoint measurement is made as accessible as temperature
and pressure with this fully configured, calibrated transmitter
that can be instantly incorporated into your air or gas
management and control system.
Operating humidity
0–100% RH
Operating temperature
-40 to +60°C (-40 to +140°F)
Operating pressure
45 MPa (450 barg / 6500 psig) max
Flow rate
1 to 5 Nl/min (2.1 to 10.6 scfh) mounted in
standard sampling block; 0 to 10 m/sec
(0 to 32.8 fps) direct insertion
Temperature coefficient
Temp compensated across operating temp range
Mechanical specification
Highlights
Ingress protection
IP66 in accordance with standard
BS EN 60529:1992, and
NEMA 4 in protection accordance with standard
NEMA 250-2003
Housing material
Stainless steel
Dimensions
L=132mm x ø27mm (L=5.19” x ø1.00”)
• Excellent sensor protection
Filter
HDPE Guard <10μm (80μm sint guard optional)
• Measurement range -100 to +20°C (-148 to +68°F)
Mounting Thread
5/8” - 18 UNF
Weight
150g (5.29oz)
Electrical connections
See table
Interchangeability
Fully interchangeable transmitters
Fault conditions
(factory programmed)
Condition
Sensor fault
Under-range dew point
Over-range dew point
• 2-wire loop powered connection
• Dew point or ppm moisture content
• IP66 (NEMA 4)
• Operating temperature -40 to +60°C (-40 to +140°F)
• Fast response
Output
23 mA
4 mA
20 mA
Dimensions
Issue No: Easidew Transmitter_97166_V2_UK_1110
23
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
4-20 mA connections 2-wire
Pin 1
4-20 mA
Pin 3
POWER
Accessories and Spare Parts
Pack of 10 replacement HDPE guards
EA2-HDPE
SS sintered guard replacement
SSG
Easidew communications kit for EA2
EA2-CK
SS sample block (5/8" UNF thread with 1/8" NPT ports)
CSB
3/4”-16 UNF to 5/8” UNF male adapter, SS (Panametrics
thread)
APT-PAN
G 1/2" to 5/8" UNF male adapter, SS (E&H or GEI thread)
APT-GEI
1/2" BSP to 5/8" UNF thread adapter
APT-BSP
Cable, 0.8m (2.62’) length with fittings + additional cable
EA2-CAB-XX
Easidew Sampler (see Accessories Section for details)
EA2-SAM
10 pk particulate filter cartridges (for SS filter unit (9996061))
SSF-PF-10PK
6mm (0.24") O.D thick walled PTFE sample tube
PTFE-XX
Ordering Example
EA2-BASE-100-HD
Easidew Transmitter, 2-wire, 4-20 mA output , measurement range -100 to +20°C (-148 to +68°F) dp, HDPE guard
Order Codes
EA2-TX - Easidew 2-wire Dew-Point Transmitter, 4-20 mA output, 5/8” UNF thread
Feature
Item
Description
Base Model
EA2-TX-BASE
Base unit
Range
EA2-100
Protection
-100 to +20°C (-148 to +68°F) dp range
EA2-wx/yz
Non-standard measurement range: w - zero value, x = full scale value, y = unit (C = °Cdp, F=°Fdp, P=ppmV)
z = Pressure for ppmV conversion in barg/psig, blank = 0 barg/0 psig)
EA2-HD
Standard HDPE guard (with protection against fine particulate (<10µm))
EA2-SS
SS sintered guard
EA2-FL
SS sintered guard with flanged mounting
© Michell Instruments 2009-2011
24
Precision Manufacturing
Easidew Transmitter
Humidity and Dew-Point Instruments
Precision Manufacturing
Easidew TX I.S.
ATEX, FM/CSA Certified Dew-Point Transmitter
Technical Specifications
Performance
Measurement range (dp)
-100 to +20°C (-148 to +68°F) dew point
Accuracy (dp)
±2°C (±3.6°F) dew point
Response time
5 mins to T95 (dry to wet)
Repeatability
0.5°C (0.9°F) dew point
Electrical output/input
Output signal
4-20 mA (2-wire connection, current source)
User configurable over range
Output
Dew point, moisture content for ppmV
Output range
Dew point: -100 to +20°C (-148 to +68°F)
Moisture content in gas: 0-3000 ppmV
Supply voltage
12–28 V DC
Load resistance
Max 250 Ω @ 12 V (500 Ω @ 24 V)
Current consumption
20 mA max
Supply voltage influence
±0.005% RH/V
Operating conditions
An ATEX, FM/CSA certified, 2-wire, rugged impedance dewpoint transmitter for continuous measurement in hazardous
area applications.
Highlights
• ATEX FM/CSA certified
• 2-wire loop powered connection
Operating humidity
0–100% RH
Operating temperature
-40 to +60°C (-40 to +140°F)
Operating pressure
45 MPa (450 barg / 6500 psig) max
Flow rate
1 to 5 Nl/min (2.1 to 10.6 scfh) mounted in
standard sampling block; 0 to 10 m/sec
(0 to 32.8 fps) direct insertion
Temperature coefficient
Temperature compensated across
operating temperature range
Mechanical specification
• Dew point or ppm moisture content
Hazardous Area Certificates
ATEX - Ex II 1G EX ia IIC T4
FM - I.S. I 1 ABCD T4 (Ta = +60°C)
CSA - IS Class 1 Div 1 Groups ABCD T4
IECEx - EX ia IIC T4 (-20°C ≤ Ta ≤ +60°C)
Ingress protection
IP66 in accordance with standard
BS EN 60529:1992, and NEMA 4 in
protection accordance with standard
NEMA 250-2003
Housing material
Stainless steel
Dimensions
L=132mm x ø27mm (L=5.19” x ø1.06”)
Filter
HDPE Guard <10μm
80μm sintered guard (optional)
Mounting Thread
5/8” - 18 UNF
Weight
150g (5.29oz)
Interchangeability
Fully interchangeable transmitters
Fault conditions
(factory programmed)
Condition
Sensor fault
Under-range dew point
Over-range dew point
Approved galvanic isolators
KFD2-CR-EX1.20200
KFD2-CR-EX1.30200
KFD0-CS-EX1.50P
KFD0-CS-EX2.50P
KFD2-STC4-EX1.H
MTL5041, MTL5040
• IP66 (NEMA 4)
• Excellent sensor protection
• Wide measurement range, calibrated -100 to +20ºC
(-148 to +68ºF) dew point
• Operating temperature: -40 to +60ºC (-40 to +140ºF)
• Fast response
Dimensions
Output
23 mA
4 mA
20 mA
Issue No: Easidew TX IS_97168_V2_UK_1110
25
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
4-20 mA connections 2-wire
Pin 1
4-20 mA
Pin 3
POWER
Accessories and Spare Parts
Pack of 10 replacement HDPE guards
EA2-HDPE
SS sintered guard replacement
SSG
Easidew communications kit for EA2
EA2-CK
SS sample block (5/8" UNF thread with 1/8" NPT ports)
CSB
3/4”-16 UNF to 5/8” UNF male adapter, SS (Panametrics
thread)
APT-PAN
G 1/2" to 5/8" UNF male adapter, SS (E&H or GEI thread)
APT-GEI
1/2" BSP to 5/8" UNF thread adapter
APT-BSP
Cable, 0.8m (2.62’) length with fittings + additional cable
EA2-CAB-XX
Easidew Sampler (see Accessories Section for details)
EA2-SAM
10 pk particulate filter cartridges (for SS filter unit (9996061))
SSF-PF-10PK
KFD0-CS-EX1.50P galvanic isolator (for Easidew PRO I.S. Pepperl & Fuchs)
GI-PF-01
6mm (0.24") O.D thick walled PTFE sample tube
PTFE-XX
Ordering Example
EA2-IS-BASE-90/20-SS
Easidew Transmitter I.S., -90 to +20°C dp range, stainless steel sintered guard
Order Codes
EA2-IS - Easidew 2-wire Dew-Point Transmitter, ATEX/FM CSA certified,4-20 mA output, 5/8” UNF thread
Feature
Item
Description
Base Model
EA2-IS-BASE
Base unit ATEX/FM CSA certified
Range
EA2-100
Protection
-100 to +20°C (-148 to +68°F) dp range
EA2-wx/yz
Non-standard measurement range: w - zero value, x = full scale value, y = unit (C = °Cdp, F=°Fdp, P=ppmV)
z = Pressure for ppmV conversion in barg/psig, blank = 0 barg/0 psig)
EA2-HD
Standard HDPE guard (with protection against fine particulate (<10µm))
EA2-SS
SS sintered guard
EA2-FL
SS sintered guard with flanged mounting
© Michell Instruments 2009-2011
26
Precision Manufacturing
Easidew TX I.S.
Humidity and Dew-Point Instruments
Precision Manufacturing
Easidew PRO I.S.
Intrinsically Safe Dew-Point Transmitter
Technical Specifications
Performance
Measurement range (dp)
-100 to +20°C (-148 to +68°F) dew point
Accuracy (dp)
±1°C (±1.8°F) dp (+20 to -60°C (+68 to
-76°F))
±2°C (±3.6°F) dp (-60 to -100°C (-76 to
-148°F))
Response time
5 mins to T95 (dry to wet)
Repeatability
0.5°C (0.9°F) dew point
Electrical output/input
Output signal
4-20 mA (2-wire connection, current source)
User configurable over range
Output
Dew point, moisture content for ppmV, ppmW
Output range
Dew point: -100 to +20°C (-148 to +68°F)
Moisture content in gas: 0-3000 ppmV
Moisture content in liquid: 0-3000 ppmW
Supply voltage
12-28 V DC
Load resistance
Max 250 Ω @ 12 V; 500 Ω @ 24 V
Current consumption
Max 23 mA depending on output signal
The Easidew PRO I.S. is a rugged instrinsically safe 2-wire dewpoint transmitter for trace moisture measurement in liquids and
gases. It is certified for use in IS Class 1 Div 1 Groups A,B,C
and D, Ex II 1G EX ia IIC T4 and I.S. I 1 ABCD T4 (Ta = +60°C)
hazardous area locations.
Saturation constants
(For moisture in liquids
measurements only)
6-point look-up table for saturation constants
up to 3000 ppmW over the temperature range
0 to 50°C.
Saturation constants for 8 common liquids can
be programmed into the Easidew PRO I.S. via
the application software. Alternatively the user
can program saturation constants manually.
Highlights
Operating conditions
•
•
•
•
±1°C (±1.8°F) accuracy
Moisture in gases or liquids capability
2-wire connection
Output configurable in ppmV and ppmW moisture content
Simple Operation
Operating humidity
0–100% RH
Operating temperature
-40 to +60°C (-40 to +140°F)
Operating pressure
45 MPa (450 barg / 6500 psig) max
Flow rate
1 to 5 Nl/min (2.1 to 10.5 scfh) mounted in
sampling block; 0 to 10 m/sec (0 to 32.8
fps) direct insertion
Mechanical specification
The Easidew Pro I.S. is easy to install and operate. It requires
a 12 to 28 V DC supply and provides a linear 4-20 mA signal
representing moisture content.
Moisture in Gases
The output can be configured by the customer, using simple
software, to any range within -100 to +20°C (-148 to +68°F)
dp, or 0-3,000 ppmV in gases. As the Easidew PRO I.S. responds
to water vapor pressure in the gas sample, it will give the user
an accurate determination of the actual dew-point at pressure
up to 45 MPa (450 barg / 6500 psig). Flow rate is not critical to
measurement accuracy (1 to 5 Nl/min (2.1 to 10.5 scfh)), though
speed of response will be improved by operating at a higher
sample flow.
Moisture in Liquids
In addition to its Moisture in Gases capabilities the Easidew
PRO I.S. can be used to monitor moisture in non-polar liquids.
It is factory programmed to provide an output in ppmw. This
requires the saturation constants of the liquid to be programmed
into the transmitter either at the factory or by the user, using
the application software, available as a free download from
www.michell.com
Hazardous Area
Certificates
ATEX - Ex II 1G EX ia IIC T4
FM - I.S. I 1 ABCD T4 (Ta = +60°C)
CSA - IS Class 1 Div 1 Groups ABCD T4
IECEx - EX ia IIC T4 (-20°C ≤ Ta ≤ +60°C)
Ingress protection
IP66 in accordance with standard
BS EN 60529:1992, and NEMA 4 in
protection accordance with standard
NEMA 250-2003
Housing material
Stainless steel
Filter
80μm sintered guard
HDPE Guard <10μm (optional)
Mounting Thread
5/8” - 18 UNF
Weight
1.27kg (2.8lbs)
Electrical connections
Screw terminal, M20 x 1.5mm
Fault conditions
(factory programmed)
Condition
Sensor fault
Under-range dew point
Over-range dew point
Approved galvanic
isolators
KFD2-CR-EX1.20200
KFD2-CR-EX1.30200
KFD0-CS-EX1.50P
KFD0-CS-EX2.50P
KFD2-STC4-EX1.H
MTL5041, MTL5040
Output
23 mA
4 mA
20 mA
Issue No: Easidew PRO IS_97208_V4_UK_1110
27
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Dimensions
4-20 mA connections 2-wire
Pin 1
4-20 mA
Pin 3
POWER



 
 






CEA-M20-NPT-SS
Cable entry adapter M20 to 1/2" BSP, brass
CEA-M20-BSP-B
Cable entry adapter M20 to 1/2" BSP, SS
CEA-M20-BSP-SS
Hazardous area cable gland, brass ø3-8mm cable
CG-M20-B
Hazardous area cable gland, SS ø3-8mm cable
CG-M20-SS
SS sintered guard replacement
SSG
KFD0-CS-EX1.50P galvanic isolator (for Easidew PRO I.S.
- Pepperl & Fuchs)
GI-PF-01
SS sample block (5/8" UNF thread with 1/8" NPT ports)
CSB
3/4"-16 UNF to 5/8" UNF male adapter, SS (Panametrics
thread)
APT-PAN
G 1/2" to 5/8" UNF male adapter, SS (E&H or GEI thread)
APT-GEI
1/2" BSP to 5/8" UNF thread adapter
APT-BSP
Communications kit for Easidew PRO I.S.
EPR-CK
Adapter for EA2-CK for use with Easidew PRO I.S.
EPR-CK-ADT
Easidew Sampler (see Accessories Section for details)
EA2-SAM
10 pk particulate filter cartridges (for SS filter unit
(9996061))
SSF-PF-10PK

Cable entry adapter M20 to 1/2" NPT, SS
5/8" UNF


CEA-M20-NPT-B



Ordering Example

EPR-IS-BASE-100
Easidew Transmitter, 2-wire, ATEX certified with -100 to +20°C (-148 to +68°F) dp range
Order Codes
EPR IS - 2-wire Dew-Point Transmitter, ATEX certified with sintered guard
Feature
Item
Description
Base Model
EPR-IS-BASE
Base unit for gas
Range
EPR-100
-100 to +20°C (-148 to +68°F) dp range
EPR-wx/yz
Non-standard measurement range: w - zero value, x = full scale value, y = unit (C = °Cdp, F=°Fdp, P=ppmV)
z = Pressure for ppmV conversion in barg/psig, blank = 0 barg/0 psig)
Base Model
EPR-LQ-IS-BASE
Base unit for liquid
Range
EPR-LQ-0/3000
0-3000 ppmW
EPR-LQ-y/z
User-programmed saturation constants (y = ppmW zero value z = ppmW full scale value)
EPR-LQ-XX
Liquid identifier
00
‘User-programmed’ CS value
01
Methane
02
Propane
03
Ethane
04
Propylene
Liquid
© Michell Instruments 2009-2011
28
05
06
07
08
09
10
Ethylene
Butane
Isobutane
Pentane
1-Butene
Cyclopentane
11
12
13
14
15
2-Butene
Isopentane
Isobutene
Pentene
Hexane


EPR-BRK
Cable entry adapter M20 to 1/2" NPT, brass
5/8" UNF
Wall mounting bracket for Easidew PRO I.S.

Accessories and Spare Parts
Precision Manufacturing
Easidew PRO I.S.

Humidity and Dew-Point Instruments
Precision Manufacturing
Easidew Online
Dew-Point Hygrometer
Technical Specifications
Performance
Measurement range
-100 to +20°C (-148 to +68°F) dew point
0–3000 ppmv
ppmv output or non-standard dew-point
range must be specified at time of order
Accuracy (dp)
±2°C (±3.6°F) dew point
Response time
5 mins to T95 (dry to wet)
Repeatability
0.5°C (0.9°F) dew point
Electrical output/input
Output signal
4–20 or 0–20 mA,
maximum load resistance 500 Ω
RS232
Supply voltage
85 to 264 V AC, 50/60 Hz
Load resistance
Max 250 Ω @ 12 V / 500 Ω @ 24 V
Current consumption
60 mA max
Operating conditions
A panel- or bench-mounting hygrometer with digital display,
analog and digital outputs and dual alarm feature, offering
excellent reliability and repeatability.
Operating humidity
0–100% RH
Operating temperature
Sensor
Monitor
-40 to +60°C (-40 to +140°F)
0 to 50°C (+32 to +122°F)
Mechanical specification
Ingress protection
Monitor
Sensor
Highlights
• Dew point or ppm moisture content
Dimensions
Monitor
IP65 (NEMA 12) front panel only
IP66 (NEMA 4)
• IP66 (NEMA 4) Sensor and IP65 (NEMA 12) Monitor (front
panel only)
Sensor
1/8 DIN case, 96 x 48 x 85mm
(3.77 x 1.88 x 3.34”) incl clearance (wxhxd)
132 x 27 A/F mm (5.13 x 1.06”) (length x
diameter across hex flats)
• Excellent sensor protection
Filter
HDPE
Weight
150g (5.29oz)
Electrical connections
Sensor cell supplied
Alarm
Front panel configuration of alarm points
Sensor cable
0.8m (2.6’) supplied as standard
max 800m (2,600’)
Mains cable
2m (6.5’) cable supplied
• Analog and digital outputs
• -100 to +20°C (-148 to +68°F) total dew-point range
• Dual alarms
• Clear and easy to read display
Dimensions
Issue No: Easidew Online_97167_V2_UK_1110
29
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
To sensor Blue cable
13
Output mA -
3
To sensor Green cable
14
Output mA +
4
To sensor Red cable
16
Alarm relay contact
7
Alarm relay contact 2 - N/O
17
Alarm relay contact
8
Alarm relay contact 2 - N/C
9
Alarm relay contact 2 - com
23
Power supply N
24
Power supply L
Accessories and Spare Parts
Pack of 10 replacement HDPE guards
EA2-HDPE
SS sintered guard replacement
SSG
Easidew communications kit for EA2
EA2-CK
SS sample block (5/8" UNF thread with 1/8" NPT ports)
CSB
KFD0-CS-EX1.50P galvanic isolator (for Easidew PRO I.S. Pepperl & Fuchs)
GI-PF-01
3/4"-16 UNF to 5/8" UNF male adapter, SS (Panametrics
thread)
APT-PAN
G 1/2" to 5/8" UNF male adapter, SS (E&H or GEI thread)
APT-GEI
1/2" BSP to 5/8" UNF thread adapter
APT-BSP
Cable, 0.8m (2.62') length with fittings + additional cable
EA2-CAB-XX
Easidew Sampler (see Accessories Section for details)
EA2-SAM
10 pk particulate filter cartridges (for SS filter unit (9996061))
SSF-PF-10PK
6mm (0.24") O.D thick walled PTFE sample tube
PTFE-XX
Ordering Example
EA2-OL-BASE-100-HD-AC-SC08
Easidew Transmitter, -100 to +20°C (-148 to +68°F) dp range, HDPE guard, 85/265 V AC power supply & 0.8m (2.62’) cable with fittings
Order Codes
EA2-OL - Easidew Online Hygrometer, 2-wire, 1/8 DIN panel mount, 2 alarms, sampling block, 0.8m (2.6’) cable assembly
Feature
Item
Description
Base Model
EA2-OL-BASE
Base unit
Range
EA2-100
Protection
Monitor
Cable
-100 to +20°C (-148 to +68°F) dp range
EA2-wx/yz
Non-standard measurement range: w - zero value, x = full scale value, y = unit (C = °Cdp, F=°Fdp, P=ppmV)
z = Pressure for ppmV conversion in barg/psig, blank = 0 barg/0 psig)
EA2-HD
Standard HDPE guard for Easidew Sensors (protection against fine particulate (<10µm))
EA2-SS
SS sintered guard
EA2-FL
SS sintered guard with flanged mounting
EA2-OL-AC
85/265 V AC power supply
EA2-OL-DC
24 V DC power supply
EA2-OL-SC08
Cable 0.8m (2.62') with fittings
EA2-OL-SCXX
Additional cable - price per meter
© Michell Instruments 2009-2011
30
Precision Manufacturing
Easidew Online
Humidity and Dew-Point Instruments
Precision Manufacturing
MDM300
Advanced Dew-Point Hygrometer
Technical Specifications
Performance
The MDM300 High-Speed Dew-Point Hygrometer provides
the fastest spot check measurement of dew-point or moisture
content in a small portable instrument packed with features
and intelligent engineering.
Measurement technology
Michell ceramic sensor
Accuracy
± 1°C from -60 to +20°C (-76 to +68°F) dp
± 2°C from -100 to -60°C (-148 to -76°F) dp
± 0.2°C (0.3°F) temperature
Measurement range
Calibrated -100 to +20°C (-148 to +68°F) dp
Readings to +30°C dp
Measurement units
°C, °F, K dew point
ppmv, ppmw for air, N2, H2, CO2, SF6
Gas temperature: %RH, gm-3, gkg-1
Option: active pressure (bara/g, psig, MPa,
KPa)
Resolution (display)
0.1 for all dp derived units and autoranging
where appropriate, e.g. ppm
Resolution (measurement)
0.1°C dew point
Typical response speed
T95 in ≤10 minutes to -70°C (-94°F)
Repeatability
Better than 0.1°C (0.2°F)
Stability
0.1°C (0.2°F)
Sensitivity
0.01°C (0.02°F) or better
Hysteresis
0.05°C (0.1°F)
Electrical output/input
An extremely fast response and accurate, stable
measurement is complemented by an instrument which
is easy to use, has data-logging and built-in sampling
components as standard, and can be supplied with a range
of accessories including a stand-alone sampling system and a
professional carry case.
Auxiliary inputs
4-20 mA external input selectable as either dp,
temperature or pressure
Battery type
NiMH 4.8V
Battery operating life
More than 48 hours of typical usage between
charges
Battery charger
Intelligent charger (supplied)
Operating conditions
Operating pressure range
35 MPa (350 barg / 5000 psig) max
Operating environment
Outdoors 0-100% RH condensing
Operating temperature
-20 to +50°C (-4 to +122°F)
• Repeatedly fast measurements in less than 10 minutes for
T95 down to -70°C (-94°F)
Storage/transport temp
-40 to +70°C (-40 to +158°F)
• Long battery life with more than 48 hours of typical usage
between charges
Display
Blue LCD graphical display
Enclosure type
Steel fiber-loaded high-impact polyamide 6
Highlights
Mechanical specification
• Best in its class: 1°C (1.8°F) accuracy
IP/NEMA rating
IP66 (NEMA 4)
• External device input 4-20 mA for dew-point, temperature
or pressure transmitters
Gas connections
1/8” NPT female (other options available)
Flow across sensor
0.2 to 2.0 Nl/min
• Bluetooth connection for trouble-free data download
Filters
• Built-in basic sensor protection sampling system allowing
measurements up to 400 barg (5800 psig)
50 micron stainless steel sinter in the inlet port
(other porosities available)
Gas wetted materials
316 stainless steel
Outline dimensions
218 x 170 x 90mm (8.6 x 6.7 x 3.5”) (dxwxh)
Weight
1.35kg (2.98lbs)
• Easy operation
General
Data Logging
8 megabytes; Log interval: 5 to 60 second;
Logs per log file: Up to 10,000
Communications
(Wireless) BluetoothTM range up to 5m (16.5ft)
Languages
English, Spanish, Portuguese, Italian, French,
German
Issue No: MDM300_97156_V3_UK_1110
31
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories and Spare Parts
Carry bag – for standard and I.S. instruments
Swagelok gas fittings – various sizes available
Cable for external dew-point sensor – various lengths available
External temperature sensor – various cable lengths available
External pressure sensor – various cable lengths available
External dew-point sensor for standard instrument – versions for standard and
I.S instruments available
Please contact us for a full list of accessories and spares with order
codes and prices
Dimensions
218mm (8.56”)
90mm (3.54”)
170mm (6.69”)
Order Codes
MDM300-STD - Advanced Portable Hygrometer
Feature
Item
Description
Base Model
MDM300-STD
Base unit
© Michell Instruments 2009-2011
32
Precision Manufacturing
MDM300
Humidity and Dew-Point Instruments
HVAC / Environmental Control
WM33 & 52
Relative Humidity and Temperature Transmitter, Wall Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
WM52: <±2% RH (10–90% RH)
WM33: <±3% RH (30–80% RH)
Accuracy at 23°C (73°F)
Temperature
WM52: ±0.2°C (±0.36°F)
WM33: ±0.3°C (±0.54°F)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical without filter (for 90% of
the step change)
Electrical output/input
Output signal
4–20 mA, 0–1, 0–5, 0–10 V
Supply voltage
14–30 V DC, 5–30 V DC
(0–1 V & mA output)
Operating conditions
Operating humidity
Probe, housing, storage
Operating temperature
Probe, Housing
Storage
The WM Series are wall-mounted units that have the ability
to display and provide an output signal of % RH, dew point
or absolute humidity and temperature. The WM Series offers
excellent measurement accuracy and stability wherever a
wall-mounted sensor is required.
5–95% non-condensing
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
PRT
Highlights
Measurement range
Pt100/1000:
-50 to +200°C (-58 to +392°F)
Accuracy
Pt100/1000: ±0.15°C
Mechanical specification
• WM33 is designed for low cost HVAC applications
Housing material
White molded polymer
• W
M52 has digital technology and is designed for accurate
measurements in a controlled environment
Weight
82g (2.89oz)
Electrical connections
Screw terminals
• Easy to re-calibrate to maintain high accuracy
Alternative outputs
Dew point
-40 to +60°C (-40 to +140°F)
Absolute humidity
0–200g/m3 (0-87.4gr/ft3)
Dimensions
Accessories and Spare Parts
19mm (0.75”) Slotted protection cap white
A000001
19mm (0.75”) PVDF filter
A000014
19mm (0.75”) PVDF filter with protection cap white
A000016
19mm (0.75”) Mesh filter with protection cap black
A000021
19mm (0.75”) Arrow stainless steel sintered filter
5/10/20 μm
A000025/26/27
19mm (0.75”) Foil filter 2μm with protection cap white
A000041
Oleophobic foil filter 0.7μm with protection cap white
A000043
19mm (0.75”) Foil filter 1.5μm with protection cap white
A000045
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: WM33 & 52_97183_V2_UK_1110
33
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
3/4 wire V DC power supply voltage
output
2 wire V DC power supply mA output
Pin 1
Pin 1
Pt100/Pt1000
Pt100/Pt1000
Pin 2
Pin 2
Pin 2
Output temperature +
Pin 1
Output temperature -
Pin 3
Common ground
Pin 2
Output temperature +
Pin 4
Output RH +
Pin 3
Output RH +
Pin 5
Power supply V +
Pin 4
Output RH -
3/4 wire with display
Pin 1
Output temperature +
Pin 2
Common ground
Pin 3
Output RH , Dew Point, Absolute
Humidity +
Pin 4
Power supply V+
Ordering Example
WM52-BASE-5-DX-H-T3
Relative humidity and temperature sensor WM52, 0-1 V output, with display, relative humidity configuration and 0 to 50°C temperature range
Order Codes
WM33 - Relative Humidity and Temperature Transmitter, Wall Mount, 1pt Calibration with 3% accuracy
Feature
Item
Description
Base Model
WM33-BASE
Base unit
Sig Output
WM33-2
4-20 mA (only possible with WM33-X, WM33-T4 or WM33-T5)
WM33-3
0-10 V
WM33-4
0-5 V
WM33-5
0-1 V
WM33-T1
-20 to +80ºC (-4 to +176ºF)
WM33-T3
0 to +50ºC (+32 to +122ºF)
WM33-T4
Pt100: -50 to +200ºC (-58 to +392ºF)
WM33-T5
Pt1000: -50 to +200ºC (-58 to +392ºF)
WM33-TX
Other output scaling available on request
WM33-X
RH signal only. No temperature output
Temp
WM52 - Relative Humidity and Temperature Transmitter, Wall Mount, 2pt Calibration with 2% accuracy
Feature
Item
Description
Base Model
WM52-BASE
Base unit
Sig Output
WM52-2
4-20 mA (only possible with WM52-X, WM52-T4 or WM52-T5)
WM52-3
0-10 V
WM52-4
0-5 V
WM52-5
0-1 V
WM52-DX
Display version
WM52-XX
No display
WM52-A
Absolute Humidity (g/m3) (only with T1)
WM52-D
Dew-point (Tdew) (only with T1)
WM52-H
Relative humidity
WM52-T1
-20 to +80ºC (-4 to +176ºF)
WM52-T3
0 to +50ºC (+32 to +122ºF)
WM52-T4
Pt100: -50 to +200ºC (-58 to +392ºF) class A
WM52-T5
Pt1000: -50 to +200ºC (-58 to +392ºF) class A
WM52-TX
Other output scaling available on request
WM52-X
RH signal only. No temperature output
Display
Moist. Sig
Temp
© Michell Instruments 2009-2011
34
HVAC / Environmental Control
WM33 & 52
Humidity and Dew-Point Instruments
Environmental Control
WM261
Digital Relative Humidity & Temperature Transmitter, Wall Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
Pt100 1/3DIN direct ±0.2°C (±0.36°F)
Current output ±0.3°C (±0.54°F)
Stability – RH sensor
<±1% RH/year
Response time
10 sec typical (for 90% of the step change)
Electrical output/input
Output signal (RH)
configurable on request
4–20 mA
0–1, 0–5, 0–10 V
Output signal (T)
configurable on request
4–20 mA
3-wire 1/3 DIN Pt100 direct
0–1, 0–5, 0–10 V
Supply voltage
Output
Output
Output
Output
4–20 mA:
0–10 V:
0–5 V:
0–1 V:
V
V
V
V
The WM261 has been developed for high precision
measurement of relative humidity and temperature. This
transmitter is available with a range of outputs.
Load resistance
Output
Output
Output
Output
4–20 mA:
0–10 V:
0–5 V:
0–1 V:
Rload < (Uv-9) / 0.02
R > 10 k Ω
R>5kΩ
R>1kΩ
Highlights
Current consumption
2 x 20 mA max
+
+
+
+
=
=
=
=
12–30 V DC
15–30 V DC
10–30 V DC
8–30 V DC
Operating conditions
• D
esigned for accurate measurement in a controlled
environment
• Temperature output scaling configurable on request
• Linearization for a specific isotherm on request
Operating humidity
Probe
Housing, Storage
0–100% RH (Non-condensing)
0–98% RH (Non-condensing)
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Dimensions
Ingress protection
IP65 (NEMA 4 level)
Housing material
PPO + POM
Dimensions
Housing
Probe
80 x 80 x 34mm (3.15 x 3.15 x 1.34”)
L=85mm, ø12mm (L=3.35”, ø0.47”)
Weight
100g (3.53oz)
Electrical connections
Screw terminals
Accessories and Spare Parts
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: WM261_97184_V2_UK_1110
35
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Version mA output and Pt100
direct
Version mA output for RH and
Temperature
Version V output and Pt100
direct
Version V output for RH and
Temperature
Pin 1
Output RH +
Pin 1
Output temperature +
Pin 1
Power supply V +
Pin 1
Power supply V +
Pin 2
Output RH -
Pin 2
Output Temperature -
Pin 2
Common ground
Pin 2
Common ground
Pin 3
Pin 3
Output RH +
Pin 3
Output RH +
Pin 3
Output Temperature +
Pin 4
Pin 4
Output RH -
Pin 4
Pin 4
Output RH +
Pt100 direct
Warning:
Temperature channels Pin 1 and
Pin 2 must be powered always
Pin 5
Pin 5
Pt100 direct
Ordering Example
WM261-BASE-A-1-Z10
Relative humidity transmitter WM261 with 4-20 mA output, Pt100 direct signal, noryl slotted cap and polyester PTFE filter
Order Codes
WM261 - Digital Relative Humidity and Temperature Transmitter, Wall Mount
Feature
Item
Description
Base Model
WM261-BASE
Base unit
Sig Output
WM261-A
4-20 mA output
WM261-B
0-10 V
WM261-C
0-5 V
WM261-D
0-1 V
WM261-0
No temperature output
WM261-1
Pt100 direct
WM261-3
-30 to +70ºC (-22 to +158ºF)
WM261-4
-30 to +20ºC (-22 to +68ºF)
WM261-5
0 to +50ºC (+32 to +122ºF)
WM261-TX
Other output scaling available on request
WM261-Z10
Noryl cap slotted & polyester PTFE filter
Temp
Filter
© Michell Instruments 2009-2011
36
Environmental Control
WM261
Humidity and Dew-Point Instruments
Precision Manufacturing
WM281
Digital Relative Humidity & Temperature Transmitter, Wall Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +70°C (-22 to +158°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5-95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step
change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
Output signal configurable on
request
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The WM281 relative humidity transmitter includes the
interchangeable Hygrosmart module. The interchangeable
module lets you recalibrate the transmitter simply by
replacing the sensor head with the Hygrosmart module. As a
result, maintenance costs are greatly reduced and down-time
is minimized.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Highlights
Ingress protection
IP67
Material
Housing
Probe
Aluminum die casting
Delrin
Dimensions
Housing
Probe
120 x 120 x 49.5mm (4.72 x 4.72 x 1.94”)
L=100mm, ø 19mm (L=3.93”, ø0.74”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
Mechanical specification
• Analog and digital output standard
• Based on the interchangeable Hygrosmart module
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
Dimensions
Accessories and Spare Parts
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
SS sintered filter
H2
SS sintered filter with teflon coating
J2
Delrin cap slotted with SS mesh filter
K7
Delrin cap slotted with PTFE filter, white
Z7
Hygrosmart with Pt100 output (RH = 0-1 V)
I7-0-00-1
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: WM281_97185_V2_UK_1110
37
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (not connected)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (not connected)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
WM281-BASE-A-K7-N030-P070
RH & temp transmitter WM281, 4-20 mA output, delrin cap slotted with stainless steel mesh filter, temp range -30 to +70ºC (-22 to +158°F)
Order Codes
WM281 - Digital Relative Humidity and Temperature Transmitter, Wall Mount
Feature
Item
Description
Base Model
WM281-BASE
Base unit
Sig Output
WM281-A
4-20 mA
WM281-B
0-10 V
WM281-C
0-5 V
WM281-D
0-1 V
WM281-E
0-20 mA
WM281-H2
SS sintered filter
WM281-J2
SS sintered filter with teflon coating
WM281-K7
Delrin cap slotted, with SS mesh filter
WM281-Z7
Delrin cap slotted, with PTFE filter, white
WM281-0000
0°C (+32°F)
WM281-N020
-20°C (-4°F)
WM281-N030
-30°C (-22°F)
WM281-P020
+20°C (+68°F)
WM281-P030
+30°C (+86°F))
WM281-P050
+50°C (+122°F)
WM281-P070
+70°C (+158°F)
WM281-XXXX
Other output scaling available on request
Filter
Temp Low
Temp High
© Michell Instruments 2009-2011
38
Precision Manufacturing
WM281
Humidity and Dew-Point Instruments
Precision Manufacturing
WM291
Digital Relative Humidity & Temperature Transmitter, Wall Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +70°C (-22 to +158°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5-95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step
change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The WM291 relative humidity transmitter includes the
interchangeable Hygrosmart module. The interchangeable
module lets you recalibrate the transmitter simply by
replacing the sensor head with the Hygrosmart module. As a
result, maintenance costs are greatly reduced and down-time
is minimized.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-20 to +70°C (-4 to +158°F)
-30 to +70°C (-22 to +158°F)
Highlights
Ingress protection
IP65 (NEMA 4 level)
Material
Housing
Probe
Aluminum die casting
Delrin
• Based on the interchangeable Hygrosmart module
Dimensions
Housing
Probe
120 x 120 x 49.5mm (4.72 x 4.72 x 1.94”)
L=100mm, ø19mm (L=3.93”, ø0.74”)
• Analog output signals selectable through software
Weight
450g (15.87oz)
• M
etric or US measurement units selectable through
software
Electrical connections
Screw terminals
Display resolution
LCD, 2 lines x 16 characters
Mechanical specification
• Three outputs
• Analog and digital output standard
• A
vailable with calculated absolute humidity, dew-point,
frost point, mixing ratio or specific enthalpy output
Dimensions
Accessories and Spare Parts
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
SS sintered filter
H2
SS sintered filter with teflon coating
J2
Delrin cap slotted with SS mesh filter
K7
Delrin cap slotted with PTFE filter, white
Z7
Hygrosmart with Pt100 output (RH = 0-1 V)
I7-0-00-1
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: WM291_97186_V2_UK_1110
39
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (optional)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (optional)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
WM291-BASE-A-0-K7-N030-P070
RH & temp transmitter WM291 for wall-mounting, 4-20 mA output, dp display -40 to +100ºC, Delrin cap slotted, with stainless steel mesh filter, temp range -30 to
+70ºC (-22 to +158ºF)
Order Codes
WM291 - Digital Relative Humidity and Temperature Transmitter, Wall Mount
Feature
Item
Description
Base Model
WM291-BASE
Base unit
Sig Output
WM291-A
4-20 mA
WM291-B
0-10 V
WM291-C
0-5 V
WM291-D
0-1 V
WM291-E
0-20 mA
WM291-0
Dew point: -40 to +100ºC
WM291-1
Mixing ratio: 0-500 gr/Kg
WM291-2
Absolute Humidity: 0 - 600 g/m3
WM291-3
Specific enthalpy: -40 to 1500 KJ/Kg
WM291-4
Frost point: -50 to +10ºC
WM291-H2
SS sintered filter
WM291-J2
SS sintered filter with teflon coating
WM291-K7
Delrin cap slotted, with SS mesh filter
WM291-Z7
Delrin cap slotted, with PTFE filter, white
WM291-0000
0°C (+32°F)
WM291-N020
-20°C (-4°F)
WM291-N030
-30°C (-22°F)
WM291-P020
+20°C (+68°F)
WM291-P030
+30°C (+86°F))
WM291-P050
+50°C (+122°F)
WM291-P070
+70°C (+158°F)
WM291-XXXX
Other output scaling available on request
3rd Output
Filter
Temp Low
Temp High
© Michell Instruments 2009-2011
40
Precision Manufacturing
WM291
Humidity and Dew-Point Instruments
Digital Relative Humidity & Temperature Transmitter, Duct Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
Pt100 1/3 DIN direct ±0.2°C (±0.36°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
Output signal (RH)
configurable on request
4–20 mA
0–1, 0–5, 0–10 V
Output signal (T)
configurable on request
4–20 mA
3-wire 1/3 DIN Pt100 direct
0–1, 0–5, 0–10 V
Supply voltage
Output
Output
Output
Output
4–20 mA:
0–10 V:
0–5 V:
0–1 V:
V+
V+
V+
V+
Load resistance
Output
Output
Output
Output
4–20 mA:
0–10 V:
0–5 V:
0–1 V:
Rload < (Uv-9) / 0.02
R > 10 k Ω
R>5kΩ
R>1kΩ
Current consumption
2 x 20 mA max
INTERCHANGEABLE
MODULE
The DT269 transmitter has a I7000 Hygrosmart module.
Thanks to this solution, the sensor can be changed on site
quickly and simply, providing greatly reduced maintenance
costs. The transmitter does not need re-calibration after the
sensor is changed.
=
=
=
=
12–30 V DC
15–30 V DC
10–30 V DC
8–30 V DC
Operating conditions
Highlights
• D
esigned for accurate measurement in a controlled
environment
• Based on the interchangeable Hygrosmart module
• Temperature output scaling configurable on request






Dimensions

Issue No: DT269_97188_V2_UK_1110


4 Off 3.3mm
(0.12")


4 Off 3.3mm
(0.12")














0–100% RH
0–98% RH (non-condensing)
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Ingress protection
IP65 (NEMA 4 level)
Material
PPO + POM
Dimensions
Housing
Probe
80 x 80 x 34.5mm (3.14 x 3.14 x 1.35”)
L=85/178mm, ø19mm (L=3.35/7.01”, ø0.75”)
Weight
100g (3.53oz)
Electrical connections
Screw terminals
Accessories and Spare Parts


Operating humidity
Probe
Housing, Storage
Mechanical specification
• Linearization for a specific isotherm on request

Environmental Control
DT269
Al mounting flange for ø19mm (0.75”) SS probes
FLA019
SS sintered filter
H4
ABS cap slotted with PTFE filter, white
Z2
Hygrosmart without Pt100 output (RH = 0-1 V)
I7-0-00-0
Hygrosmart with Pt100 output (RH = 0-1 V)
I7-0-00-1
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC


41
4 Off 3.3mm
(0.12")
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Version mA output and Pt100
direct
Version mA output for RH and
Temperature
Version V output and Pt100
direct
Version V output for RH and
Temperature
Pin 1
Output RH +
Pin 1
Output temperature +
Pin 1
Power supply V +
Pin 1
Power supply V +
Pin 2
Output RH -
Pin 2
Output Temperature -
Pin 2
Common ground
Pin 2
Common ground
Pin 3
Pin 3
Output RH +
Pin 3
Output RH +
Pin 3
Output Temperature +
Pin 4
Pin 4
Output RH -
Pin 4
Pin 4
Output RH +
Pt100 direct
Warning:
Temperature channels Pin 1
and Pin 2 must be powered
always
Pin 5
Pin 5
Pt100 direct
Ordering Example
DT269-BASE-A-4-E0-H4
RH & temp transmitter DT269, 4-20 mA output, -30 to +20ºC (-22 to +68ºF) temp range, 160mm (6.30”) probe length, stainless steel sintered filter
Order Codes
DT269 - Digital Relative Humidity and Temperature Transmitter, Duct Mount
Feature
Item
Description
Base Model
DT269-BASE
Base unit
Sig Output
DT269-A
4-20 mA
DT269-B
0-5 V
DT269-C
0-10 V
DT269-D
0-1 V
DT269-0
No temperature output
DT269-1
Pt100 direct
DT269-3
-30 to +70ºC (-22 to +158ºF)
DT269-4
-30 to +20ºC (-22 to +68ºF)
DT269-5
0 to +50ºC (+32 to +122ºF)
DT269-6
-20 to +80ºC (-4 to +176ºF)
DT269-TX
Other output scaling available on request
DT269-E0
160mm (6.29") probe length
DT269-E1
290mm (11.41") probe length
DT269-H4
SS sintered filter
DT269-Z2
ABS cap slotted with PTFE filter, white
Temp
Length
Filter
© Michell Instruments 2009-2011
42
Environmental Control
DT269
Humidity and Dew-Point Instruments
Precision Manufacturing
DT722
Rugged Industrial Relative Humidity and Temperature Transmitter, Duct
Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-40 to +150°C (-40 to +302°F)
Accuracy at 25°C (77°F)
Humidity
<±2% RH (5-95% RH)
Accuracy at 25°C (77°F)
Temperature
±0.2°C (±0.36°F) typical
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step
change)
Electrical output/input
Output signal
4–20 mA
Supply voltage
8–35 V DC
Supply voltage influence
±0.01 % RH/V typical
Operating conditions
The DT722 is a rugged industrial relative humidity and
temperature transmitter designed for process applications
where accurate, stable measurement and control of humidity
and temperature is required.
Operating humidity
Probe, Housing, Storage
10–95% RH (non-condensing)
Operating temperature
Probe
Housing
Storage
-40 to +150°C (-40 to +302°F)
-30 to +70°C (-22 to +158°F)
-40 to +75°C (-40 to +167°F)
Mechanical specification
Highlights
• D
esigned for accurate measurement in a harsh
environment
• Can withstand temperatures up to 150°C (300°F)
Ingress protection
IP65 (NEMA 4 level)
Housing material
Stainless steel
Weight
200mm: 800g (7.87”: 28.22oz)
300mm: 900g (11.81”: 31.75oz)
500mm: 1040g (19.69”: 2.29lb)
Electrical connections
4 pin, M12
• Stainless steel housing
• Calculated moisture signal output, optional
Dimensions
Accessories and Spare Parts
19mm (0.75") Slotted protection cap black
A000002
19mm (0.75") PVDF filter
A000014
19mm (0.75") PVDF filter w/ protection cap black
A000015
19mm (0.75") Mesh filter w/ protection cap black
A000021
19mm (0.75”) Arrow SS sintered filter 5μm / 10μm / 20μm
A000025/26/27
19mm (0.75") connector, no cable, w/screw terminal
A000030
19mm (0.75”) Connector, with cable (customer spec length)
A000030XM
19mm (0.75") connector with 2m (6.5') cable
A000031
19mm (0.75") connector with 5m (16') cable
A000032
19mm (0.75") Foil filter 2µm w/protection cap black
A000040
Oleophobic foil filter 0.7µm w/prot cap black
A000042
19mm (0.75") Foil filter 1.5µm w/protection cap black
A000044
3/4" NPT SS adj. fitting for SS probes
A000100
Al mounting flange for ø19mm (0.75") SS probes (outside
ø80mm (3.15"))
A000110
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: DT722_97191_V2_UK_1110
43
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Connections
Cable
Pin
White
Pin 1
Output RH +
Brown
Pin 3
Output RH -
Green
Pin 4
Output T +
Yellow
Pin 2
Output T -
Connect RH + with T + by user
Ordering Example
DT722-BASE-SX-A-HT0-03-CA-F02
RH & temp transmitter DT722, no display, Output 1 - calc absolute humidity, Output 2 - temp output 0 to +100ºC (+32 to +212ºF), 300mm (11.81”) probe length, no
cable, 19mm slotted protection cap black
Order Codes
DT722 - Rugged Industrial Relative Humidity and Temperature Transmitter, Duct Mount
Feature
Item
Description
Base Model
DT722-BASE
Base unit
Display
DT722-SD
Display
DT722-SX
No display
DT722-H
RH
DT722-D
Calculated dp temp & temp output (Range (Td) -40 to +60ºC (-40 to +140ºF)) (Choose only HT0)
DT722-A
Calc absolute humidity (Abs) & temp output (Range Abs from 0-200g/m3) (Choose only HT0)
DT722-W
Calculated wetbulb temp & temp output (Range (Tw) -40 to +60ºC (-40 to +140ºF)) (Choose only HT0)
DT722-HT0
0 to +100ºC (+32 to +212ºF)
DT722-HTS
-40 to +150ºC (-40 to +302ºF)
DT722-TX
Other output scaling available on request
DT722-02
200mm (7.87") probe length
DT722-03
300mm (11.81") probe length
DT722-05
500mm (19.69") probe length
DT722-09
900mm (35.43") probe length
DT722-15
1500mm (50.06") probe length
DT722-CA
No cable
DT722-CB
19mm (0.75") connector, no cable, w/screw terminal
DT722-CC
19mm (0.75") connector with 2m (6.5') cable
DT722-CD
19mm (0.75") connector with 5m (16') cable
DT722-F02
19mm (0.75”) slotted protection cap black
DT722-F15
19mm (0.75”) PVDF filter with protection cap black
DT722-F21
19mm (0.75”) Mesh filter with protection cap, black
DT722-F25
19mm (0.75”) Arrow SS sintered filter 5μm
DT722-F26
19mm (0.75”) Arrow SS sintered filter 10μm
DT722-F27
19mm (0.75”) Arrow SS sintered filter 20μm
DT722-F40
19mm (0.75”) Foil filter 2μm with protection cap black
DT722-F42
Oleophobic foil filter 0.7μm with protection cap black
DT722-F44
19mm (0.75”) Foil filter 1.5µm w/protection cap black
Moist. Sig
Temp
Length
Cable
Filter
© Michell Instruments 2009-2011
44
Precision Manufacturing
DT722
Humidity and Dew-Point Instruments
Precision Manufacturing
DT282
Digital Relative Humidity and Temperature Transmitter - Duct Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +70°C (-22 to +158°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
MODULE
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The DT282 relative humidity transmitter includes the
interchangeable Hygrosmart module. The interchangeable
module lets you recalibrate the transmitter simply by
replacing the sensor head with the Hygrosmart module. As a
result, maintenance costs are greatly reduced and down-time
is minimized.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Highlights
• Analog and digital output standard
Ingress protection
IP67
Material
Housing
Probe
Aluminum die casting
Stainless steel AISI 316
Dimensions
Housing
Probe
• Based on the interchangeable Hygrosmart module
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
120 x 120 x 49.5mm (4.72 x 4.72 x 1.94”)
L=250/500mm ø19mm
(L=9.84/19.68” ø0.74”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
Dimensions
Accessories and Spare Parts
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
Al mounting flange for ø19mm (0.75") SS probes
FLA019
SS sintered filter
H2
SS sintered filter with teflon coating
J2
AISI 316 cap slotted with SS mesh filter
K6
SS cap slotted with PTFE filter
Z6
Hygrosmart with Pt100 output (RH = 0-1 V)
I7-0-00-1
You can check your hygrometer with the Control Kit HKC which
is based on the principle of non-saturated salt solutions. Refer to
technical data sheet CONTROL KIT
HKC
Issue No: DT282_97189_V2_UK_1110
45
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (not connected)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (not connected)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
DT282-BASE-A-01-K6-N030-P070
RH & temp transmitter DT282, 4-20 mA output, stainless steel probe 250mm (9.84”), AISI 316 cap slotted with stainless steel mesh filter, temp range -30 to +70ºC
(-22 to +158ºF)
Order Codes
DT282 - Digital Relative Humidity and Temperature Transmitter, Duct Mount
Feature
Item
Description
Base Model
DT282-BASE
Base unit
Sig Output
DT282-A
4-20 mA
DT282-B
0-10 V
DT282-C
0-5 V
DT282-D
0-1 V
DT282-E
0-20 mA
DT282-01
250mm (9.84")
DT282-02
500mm (19.68")
DT282-H2
SS sintered filter
DT282-J2
SS sintered filter with teflon coating
DT282-K6
AISI 316 cap slotted with SS mesh filter
DT282-Z6
SS cap slotted with PTFE filter
DT282-0000
0°C (+32°F)
DT282-N020
-20°C (-4°F)
DT282-N030
-30°C (-22°F)
DT282-P020
+20°C (+68°F)
DT282-P030
+30°C (+86°F))
DT282-P050
+50°C (+122°F)
DT282-P070
+70°C (+158°F)
DT282-XXXX
Other output scaling available on request
Length
Filter
Temp Low
Temp High
© Michell Instruments 2009-2011
46
Precision Manufacturing
DT282
Humidity and Dew-Point Instruments
Precision Manufacturing
DT284
Digital Relative Humidity and Temperature Transmitter - Duct Mount
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +140°C (-22 to +284°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
PROBE
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The DT284 relative humidity transmitter uses the Hygrosmart
module, integrated in the interchangeable probe. This device
can be used in high-temperature applications due to the
remote placing of the measurement element and its small
overall size.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +140°C (-22 to +284°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Highlights
• 12mm (0.47”) probe diameter
• Analog and digital output standard
Ingress protection
IP67
Material
Housing
Probe
Aluminum die casting
Stainless steel
Dimensions
Housing
Probe
• Interchangeable probe
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
120 x 120 x 49.5mm (4.72 x 4.72 x 1.94”)
L=250/500mm ø12mm
(L=9.84/19.68” ø0.47”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
• Can withstand temperatures up to 140°C (284°F)
Accessories and Spare Parts
Dimensions
SS probe 250mm (9.84"), SS cover & mesh filter
USTE003
SS probe 500mm (19.69"), SS cover & mesh filter
USTE010
SS probe 250mm (9.84"), SS cover & sinter filter
USTE011
SS probe 500mm (19.69"), SS cover & sinter filter
USTE012
PEEK probe 250mm (9.84") & cover, SS mesh filter
USTE013
PEEK probe 500mm (19.69") & cover, SS mesh filter
USTE014
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
Al mounting flange for ø12mm (0.47") SS probes
FLA012
SS sintered filter
H3
SS sintered filter with teflon coating
J3
SS mesh filter
K8
PEEK protection cap with SS mesh filter
K9
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt solutions.
Refer to technical data sheet CONTROL KIT
HKC
Issue No: DT284_97190_V2_UK_1110
47
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (not connected)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (not connected)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
DT284-BASE-A-11-N030-P140
RH & temp transmitter DT284, 4-20 mA output, stainless steel probe 250mm (9.84”), stainless steel cover and sintered filter, temp range -30 to +140ºC (-22 to +284ºF)
Order Codes
DT284 - Digital Relative Humidity and Temperature Transmitter, Duct Mount
Feature
Item
Description
Base Model
DT284-BASE
Base unit
Sig Output
DT284-A
4-20 mA
DT284-B
0-10 V
DT284-C
0-5 V
DT284-D
0-1 V
DT284-E
0-20 mA
DT284-3
SS probe 250mm (9.84"), SS cover & mesh filter
DT284-10
SS probe 500mm (19.69"), SS cover & mesh filter
DT284-11
SS probe 250mm (9.84"), SS cover & sinter filter
DT284-12
SS probe 500mm (19.69"), SS cover & sinter filter
DT284-13
PEEK probe 250mm (9.84") & cover, SS mesh filter
DT284-14
PEEK probe 500mm (19.69") & cover, SS mesh filter
DT284-0000
0°C (+32°F)
DT284-N020
-20°C (-4°F)
DT284-N030
-30°C (-22°F)
DT284-P020
+20°C (+68°F)
DT284-P030
+30°C (+86°F))
DT284-P050
+50°C (+122°F)
DT284-P070
+70°C (+158°F)
DT284-P100
+100°C (+212°F)
DT284-P140
+140°C (+284°F)
DT284-XXXX
Other output scaling available on request
Probe Type
Temp Low
Temp High
© Michell Instruments 2009-2011
48
Precision Manufacturing
DT284
Humidity and Dew-Point Instruments
Precision Manufacturing
WR283
Digital Relative Humidity and Temperature Transmitter - Remote Probe
for High Temperatures
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +200°C (-22 to +392°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
PROBE
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The WR283 relative humidity sensor uses the Hygrosmart
module, integrated in the interchangeable probe and cable.
This device can be used in high-temperature applications
thanks to the remote placing of the measurement element
and its small overall size. The interchangeable probe allows
for simple re-calibration and lower maintenance costs.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +200°C (-22 to +392°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Highlights
• Analog and digital output standard
• Interchangeable probe
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
Ingress protection
IP67
Material
Housing
Probe
Aluminum die casting
Stainless steel
Dimensions
Housing
Probe
120 x 120 x 51mm (4.72 x 4.72 x 2.00”)
L=134mm, ø12mm (L=5.27”, ø0.47”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
• Can withstand temperatures up to 200°C (392°F)
Accessories and Spare Parts
Dimensions
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
Al mounting flange for ø12mm (0.47") SS probes
FLA012
SS sintered filter
H3
SS sintered filter with teflon coating
J3
SS mesh filter
K8
PEEK protection cap with SS mesh filter
K9
SS probe, cover & mesh filter, 2m (6.56') cable
USTE002
SS probe, cover & mesh filter, 4m (13.12') cable
USTE005
SS probe, cover & sinter filter, 2m (6.56') cable
USTE006
SS probe, cover & sinter filter, 4m (13.12') cable
USTE007
PEEK probe, cover, SS mesh filter, 2m (6.56') cable
USTE008
PEEK probe, cover, SS mesh filter, 4m (13.12') cable
USTE009
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt solutions.
Refer to technical data sheet CONTROL KIT
HKC
Issue No: WR283_97192_V2_UK_1110
49
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (not connected)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (not connected)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
WR283-BASE-A-7-N030-P180
RH & temp transmitter WR283 with 4-20 mA output, stainless steel probe with 4m (13.12’) cable and stainless steel sintered filter, temp range -30 to +180ºC
(-22 to +356ºF)
Order Codes
WR283 - Digital Relative Humidity and Temperature Transmitter, Remote Probe for High Temperatures
Feature
Item
Description
Base Model
WR283-BASE
Base unit
Sig Output
WR283-A
4-20 mA
WR283-B
0-10 V
WR283-C
0-5 V
WR283-D
0-1 V
WR283-E
0-20 mA
WR283-2
SS probe, cover & mesh filter, 2m (6.56') cable
WR283-5
SS probe, cover & mesh filter, 4m (13.12') cable
WR283-6
SS probe, cover & sinter filter, 2m (6.56') cable
WR283-7
SS probe, cover & sinter filter, 4m (13.12') cable
WR283-8
PEEK probe, cover, SS mesh filter, 2m (6.56') cable
WR283-9
PEEK probe, cover, SS mesh filter, 4m (13.12') cable
WR283-0000
0°C (+32°F)
WR283-N020
-20°C (-4°F)
WR283-N030
-30°C (-22°F)
WR283-P020
+20°C (+68°F)
WR283-P030
+30°C (+86°F))
WR283-P050
+50°C (+122°F)
WR283-P070
+70°C (+158°F)
WR283-P100
+100°C (+212°F)
WR283-P140
+140°C (+284°F)
WR283-P150
+150°C (+302°F)
WR283-P180
+180°C (+356°F)
WR283-P200
+200°C (+392°F)
WR283-XXXX
Other output scaling available on request
Probe Type
Temp Low
Temp High
© Michell Instruments 2009-2011
50
Precision Manufacturing
WR283
Humidity and Dew-Point Instruments
Precision Manufacturing
WR285
Digital Relative Humidity Transmitter - Remote Probe for Pressurized
Applications up to 30 bar (3Mpa)
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Accuracy at 25°C (77°F)
Humidity
<±2% RH (5–95% RH)
Stability – RH Sensor
±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
HYGROSMART ®
INTERCHANGEABLE
PROBE
The WR285 relative humidity sensor uses the Hygrosmart
module, integrated in the interchangeable probe. This device
can be used in high-temperature applications due to the
remote measurement element and its small overall size. The
interchangeable probe allows for simple re-calibration and
lower maintenance costs.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +120°C (-22 to +248°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Highlights
• Up to 30 bar (400 PSI) pressure
• Analog and digital output standard
Ingress protection
IP67
Material
Housing
Probe
Aluminum die casting
Stainless steel
Dimensions
Housing
Probe
120 x 120 x 51mm (4.72 x 4.72 x 2.00”)
L=148mm, ø18mm (L=5.82”, ø0.70”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
• Interchangeable probe
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
• Can withstand temperatures up to 120°C (248°F)
Dimensions
Accessories and Spare Parts
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
SS interchangeable probe with 2m (6.56') cable
USTE015
SS cap slotted with mesh filter
K1
SS cap slotted with PTFE filter
Z1
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Issue No: WR285_97193_V2_UK_1110
51
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Not connected
12
Not connected
6
Not connected
13
Output Channel 3 (not connected)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (not connected)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
WR285-BASE-A-15-K1
Relative humidity transmitter WR285, 4-20 mA output, stainless steel probe with 2m (6.56’) cable, stainless steel cap with mesh filter
Order Codes
WR285: Digital Relative Humidity Transmitter - Remote Probe for Pressurized Applications up to 30 bar (3Mpa)
Feature
Item
Description
Base Model
WR285-BASE
Base unit
Sig Output
WR285-A
4-20 mA
WR285-B
0-10 V
WR285-C
0-5 V
WR285-D
0-1 V
WR285-E
0-20 mA
Probe Type
WR285-15
SS interchangeable probe with 2m (6.56') cable
Filter
WR285-K1
SS cap slotted with mesh filter
WR285-Z1
SS cap slotted with PTFE filter
© Michell Instruments 2009-2011
52
Precision Manufacturing
WR285
Humidity and Dew-Point Instruments
Precision Manufacturing
WR293
Digital Relative Humidity and Temperature Transmitter - Remote Probe
for High Temperatures
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +200°C (-22 to +392°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.4°C (±0.72°F)
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step change)
Electrical output/input
HYGROSMART ®
INTERCHANGEABLE
PROBE
Output signal
0–1, 0–5, 0–10 V
0–20 mA, 4–20 mA, RS485
Supply voltage
15 - 27 V AC / 18 - 38 V DC
Load resistance
Current output: R ≤ 500 Ω
Power consumption
1.7 W
Operating conditions
The WR293 relative humidity transmitter uses the Hygrosmart
module, integrated in the interchangeable probe. This device
can be used in high-temperature applications due to the
remote measurement element and its small overall size. The
interchangeable probe allows for simple re-calibration and
lower maintenance costs.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe
Housing
Storage
-30 to +200°C (-22 to +392°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specification
Highlights
• Three outputs
• Analog and digital output standard
• Interchangeable probe
• Analog output signals selectable through software
• M
etric or US measurement units selectable through
software
• Available with calculated absolute humidity, dew-point,
frost point, mixing ratio or specific enthalpy output
Ingress protection
IP65 (NEMA 4 level)
Material
Housing
Probe
Aluminum die casting
Stainless steel
Dimensions
Housing
Probe
120 x 120 x 51mm (4.72 x 4.72 x 2.00”)
L=134mm, ø12mm (L=5.27”, ø0.47”)
Weight
450g (15.87oz)
Electrical connections
Screw terminals
Display resolution
LCD, 2 lines x 16 characters
Accessories and Spare Parts
• Can withstand temperatures up to 200°C (392°F)
Dimensions
RS422/485 to PC (RS232) converter
330185
USB cable/software for configuration
F035263
Al mounting flange for ø12mm (0.47") SS probes
FLA012
SS sintered filter
H3
SS sintered filter with teflon coating
J3
SS mesh filter
K8
PEEK protection cap with SS mesh filter
K9
SS probe, cover & mesh filter, 2m (6.56') cable
USTE002
SS probe, cover & mesh filter, 4m (13.12') cable
USTE005
SS probe, cover & sinter filter, 2m (6.56') cable
USTE006
SS probe, cover & sinter filter, 4m (13.12') cable
USTE007
PEEK probe, cover, SS mesh filter, 2m (6.56') cable
USTE008
PEEK probe, cover, SS mesh filter, 4m (13.12') cable
USTE009
You can check your hygrometer with the Control Kit HKC which
is based on the principle of non-saturated salt solutions. Refer
to technical data sheet CONTROL KIT
HKC
Issue No: WR293_97194_V2_UK_1110
53
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Pin
1
Power Supply V +
8
Output Channel 2 Ground
2
Power Supply V -
9
RS485 Data +
3
Output RS485 Ground
10
RS485 Data -
4
Ground
11
Not connected
5
Output Channel 1 Temperature +
12
Not connected
6
Output Channel 1 Ground
13
Output Channel 3 (optional)
7
Output Channel 2 RH +
14
Output Channel 3 Ground (optional)
Do not connect pin 2 (V -) to pin 4 (Ground)
Ordering Example
WR293-BASE-A-0-IP6-N030-P180
RH & temp transmitter WR293, 4-20 mA output, dew point calculated, stainless steel probe with 2m (6.56’) cable and stainless steel sintered filter, -30 to +180ºC
(-22 to +356ºF) temp range
Order Codes
WR293 - Digital Relative Humidity and Temperature Transmitter - Remote Probe for High Temperatures
Feature
Item
Description
Base Model
WR293-BASE
Base unit
Sig Output
WR293-A
4-20 mA
WR293-B
0-10 V
WR293-C
0-5 V
WR293-D
0-1 V
WR293-E
0-20 mA
WR293-0
Dew point: -40 to +100ºC
WR293-1
Mixing ratio: 0-500 gr/Kg
WR293-2
Absolute Humidity: 0-600 g/m3
WR293-3
Specific enthalpy: -40 to 1500 KJ/Kg
WR293-4
Frost point: -50 to +10ºC
WR293-IP2
SS probe, cover & mesh filter, 2m (6.56') cable
WR293-IP5
SS probe, cover & mesh filter, 4m (13.12') cable
WR293-IP6
SS probe, cover & sinter filter, 2m (6.56') cable
WR293-IP7
SS probe, cover & sinter filter, 4m (13.12') cable
WR293-IP8
PEEK probe, cover, SS mesh filter, 2m (6.56') cable
WR293-IP9
PEEK probe, cover, SS mesh filter, 4m (13.12') cable
WR293-0000
0°C (+32°F)
WR293-N020
-20°C (-4°F)
WR293-N030
-30°C (-22°F)
WR293-P020
+20°C (+68°F)
WR293-P030
+30°C (+86°F))
WR293-P050
+50°C (+122°F)
WR293-P070
+70°C (+158°F)
WR293-P100
+100°C (+212°F)
WR293-P140
+140°C (+284°F)
WR293-P150
+150°C (+302°F)
WR293-P180
+180°C (+356°F)
WR293-P200
+200°C (+392°F)
WR293-XXXX
Other output scaling available on request
3rd Output
Probe Type
Temp Low
Temp High
© Michell Instruments 2009-2011
54
Precision Manufacturing
WR293
Humidity and Dew-Point Instruments
Capacitive Relative Humidity Sensor
Technical Specifications
Response time
90% of scale for a step change
from 11% to 75% RH
Operating range
Humidity
Temperature
Pressure
Mixing ratio
The operating principle of these capacitive relative humidity
sensors are based on the hygroscopic properties of their
polymer, which is used like a dielectric in a capacitor. The
polymer gets in equilibrium with its humid environment
quickly, and reversibly, and changes its capacity value
depending on the humidity level.
H5000
H5100
4 sec
4 sec
0–100% RH
-30 to +200°C
(-22 to +392°F)
0.04–30 bar
(0.6-400 PSI)
0–100% RH
-30 to +100°C
(-22 to +212°F)
0.04–30 bar
(0.6-400 PSI)
250g (8.82oz) water/Kg dry air
Nominal capacity
75% RH @ 23°C (73°F)
500 pF ± 10%
Sensitivity
11-75% RH @ 23°C (73°F)
0.86 pF / % RH
Linearity
11–90% RH @ 23°C (73°F)
± 2.5% RH
Long term stability
(12 months) control @
11% RH
< 1% at 23°C (73°F)
Maximum air speed
(without protection)
< 20m/sec
Hysteresis
Typical value = 0.5% RH
D Factor loss tangent @10 KHz
75% RH @ 23°C (73°F)
Supply voltage
Peak-to-peak
Typical value = 0.007
2.5 V AC
DC component < 0.2 V
Operating frequency range
Highlights
Protection cap
Weight
• Capacitive thin film sensor
5–300 KHz
No
0.1g (0.0004oz)
Yes
1g (0.035oz)
• Measuring range: RH 0–100%, Temp: -30 to +200°C
(-22 to +365°F)
• Mixing ratio: 250g (8.82oz) water/kg of dry air
• Low hysteresis
Order Codes
• Response time: 4 seconds
H5-000 without protective housing
Minimum order 50 pieces
H5-100 with protective housing
Minimum order 50 pieces
Dimensions
0.6 mm
(0.023")
6.0 mm (0.23") 0.1mm
6.0 mm (0.23") 0.1mm
Sensors
H5000 & 5100
1.0
0.039"
3.2 mm (0.12")
1.8
0.071" mm
Issue No: H5000_97197_V2_UK_1110
55
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Sensors
H6000 & 6100
Capacitive Relative Humidity Sensor
Technical Specifications
Response time
90% of scale for a step change
from 11 to 75% RH
Operating range
Humidity
Temperature
Pressure
Mixing ratio
20 sec
0–100% RH
-30 to +200°C
(-22 to +392°F)
0.04–30 bar
(0.6-400 PSI)
0–100% RH
-30 to +100°C
(-22 to +212°F)
0.04–30 bar
(0.6-400 PSI)
500 pF ± 10%
Sensitivity
11–75% RH @ 23°C (73°F)
0.86 pF / % RH
Linearity
11–90% RH) @ 23°C (73°F)
± 2.5% RH
< 1% at 23°C (73°F)
< 20m/sec
Hysteresis
Typical value = 0.5% RH
D Factor loss tangent @10 KHz
75% RH @ 23°C (73°F)
Typical value = 0.007
Supply voltage
Peak-to-peak
2.5 V AC
DC component < 0.2 V
Operating frequency range
5/300 KHz
Protection cap
Weight
• Suitable for corrosive atmosphere
20 sec
250g (8.82oz) water/Kg dry air
Max. air speed
(without protection)
Highlights
H6100
Nominal capacity
75% RH @ 23°C (73°F)
Long term stability
(12 months) control @
11% RH
The operating principle of capacitive relative humidity sensors
are based on the hygroscopic properties of their polymer,
which is used like a dielectric in a capacitor. The polymer
gets in equilibrium with its humid environment quickly, and
reversibly, and changes its capacity value depending on the
humidity level.
H6000
No
0.1g (0.0004oz)
Yes
1g (0.035oz)
• Teflon coated
• Capacitive thin film sensor
• Measuring range: 0–100% RH, Temp: -30 to +200°C
(-22 to +365°F)
• Mixing ratio: 250g (8.82oz) water/kg of dry air
Order Codes
• Low hysteresis
• Response time: 20 seconds
H6-000 without protective housing
Minimum order 50 pieces
H6-100 with protective housing
Minimum order 50 pieces
Dimensions
0.6 mm
(0.023")
6.0 mm (0.23") 0.1mm
6.0 mm (0.23") 0.1mm
1.0
0.039"
3.2 mm (0.12")
Issue No: H6000_97198_V2_UK_1110
© Michell Instruments 2009-2011
56
1.8
0.071" mm
Humidity and Dew-Point Instruments
Sensors
I7000 & 7400 (Hygrosmart)
Interchangeable Module for Relative Humidity
Technical Specifications
Performance
Measurement range (RH)
0–100% RH
Measurement range (T)
-30 to +85°C (-22 to +185°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
±0.2°C (±0.36°F) Pt100 1/3 DIN direct
Stability – RH Sensor
<±1% RH/year
Response time – RH Sensor
<10 sec typical (for 90% of the step
change)
Electrical output/input
Output signal (RH)
I7000: 0–1 V
I7400: 0.2–1 V
Digital, variable frequency output
Output signal (T)
3-wire 1/3 DIN Pt100 direct
Supply voltage
5 V DC ±5%
Power consumption
≤ 1.5 mA max
Operating conditions
The I7000 (Hygrosmart) Series is interchangeable without the
need for re-calibration. The small size allows its integration
in any equipment while the plug-and-play system allows fast
replacement even by non-skilled staff.
Operating humidity
Probe, Housing, Storage
0–100% RH
Operating temperature
Probe, Housing
Storage
-30 to +85°C (-22 to +185°F)
-40 to +85°C (-40 to +185°F)
Highlights
Mechanical specification
• Interchangeable without re-calibration
Housing material
NORYL PPo UL 94 V0
Dimensions
L=33mm, ø14mm (L=1.3”, ø0.55”)
Weight
3g (0.1oz)
Electrical connections
RH: 3-wire
T: 3-wire
• Sensor response time: <10sec
• Linearization for a specific isotherm on request
• Can be used up to peak temperatures of 95°C (200°F)
Dimensions
HYGROSMART ®
INTERCHANGEABLE
MODULE
Accessories and Spare Parts
Mini flange
1A01210
Connecting kit with wires
6A06350
Connecting kit for PCB
6A05130
Issue No: I7000_97202_V2_UK_1110
57
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Electrical Connections
Pin
Digital output
1
Output frequency
Characterized by a variable frequency pulse train in function of the relative
humidity.
2
Common Ground
3
Power Supply V + (5 V DC)
4
Output RH + 0-1 V DC (I7000) (Output 0.2-1 V DC (I7400)
5 <f<30 Hz
T on
5
T off
Pt100
6
% RH=[(T on/T off)*2049-1]/16.12
7
Order Codes
I7000 & I7400 - Interchangeable Module for Relative Humidity
Feature
Item
Description
Base Model
I7-0-00-0
0-1 V without temp configuration
Type
I7-0-00-1
0-1 V with direct Pt100
I7-4-00-0
0.2-1 V without temp configuration
I7-4-00-1
0.2-1 V with direct Pt100
© Michell Instruments 2009-2011
58
Sensors
I7000 & I7400
Humidity and Dew-Point Instruments
Calibration
S503
Relative Humidity Generator for Calibrations
Technical Specifications
Humidity
Generation range
10–90% RH in steps of 0.1% RH
Accuracy
±2% RH or better (5–95% RH)
Stability chamber
Better than ±0.5%
Stabilization time to set point
<10 minutes
Temperature
Temperature accuracy
±0.3°C (±0.54°F) - internal reference
Operating temperature
(ambient)
+15 to +35°C (+59 to +95°F)
Sensor under Calibration
Voltage read out
0–1, 0–5, 0–10 V
Current read out
4–20 mA
Voltage supply
15 V DC, ±10% at 30 mA max
General
The S503 Humidity Generator enables users of humidity
sensors, transmitters and portable devices to quickly and
accurately generate a stable humidity in a test chamber to
validate or calibrate sensors.
Highlights
• Generates humidity levels between 10–90% RH
Probe ports
7 off – sensor body diameters 5 to 25mm
(0.2 to 0.98”) accommodated by port
adapters
Desiccant chamber
25g (0.88oz) capacity
Saturation chamber
25ml capacity, distilled water
Display
3½ digit LCD, 13mm (0.5”) characters
Supply
12 V DC (100 - 240 V AC adapter
included)
Weight
1.85kg (4.08lb)
• Highly portable
• Fast stabilization of chamber humidity
• Independent reference hygrometer – optional
• Multiple sensors can be calibrated at the same time
Dimensions
Notes:
Hole A = Drain hole with cap
Hole B = Power hole for adapter
Issue No: S503_97199_V2_UK_1110
59
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories and Spare Parts
0.25kg (0.55lbs) desiccant (orange)
A000171
ø18.5mm (0.73") blind stop
A000200
Carrying case for the S503
A000230
Water bottle
A000242
Tool for changing the port adapters
A000265
SS port adapter for Optidew
A000272
Polymer port adpt ø18.5mm (0.73") to ø3mm (0.19") (for Optidew
probe)
A000273
Blind stop for Optidew adapter
A000277
Blind stop for PRT adapter
A000278
Al adapter & blind stop (to be modified by customer) (M30x1)
A000280
Al port adapter ø client specific & blind stop (M30x1)
A000280X
Al port adpt for ø12mm (0.47") probe, blind stop (M30x1)
A000281
Al port adpt for ø13.5mm (0.53") probe, blind stop (M30x1)
A000282
Al port adpt for ø14mm (0.55") probe, blind stop (M30x1)
A000283
Al port adpt for ø15mm (0.59") probe, blind stop (M30x1)
A000284
Al port adpt for ø18.5mm (0.73") probe, blind stop (M30x1)
A000285
ø18.5mm (0.73") molded polymer port adpt (for ø8mm (0.31") probes)
A000180
ø18.5mm (0.73") molded polymer port adpt (for ø12mm (0.47") probes)
A000190
Al port adpt for ø19mm (0.75") probe, blind stop (M30x1)
A000286
Al port adpt for ø24mm (0.95") probe, blind stop (M30x1)
A000287
Al port adpt for ø25mm (0.98") probe, blind stop (M30x1)
A000288
Optidew Vision reference hygrometer with sensor
OPT-V-01
Control sensor
HX757
S503 calibration set
Order Codes
S503 - Relative Humidity Generator for Calibrations
Feature
Item
Description
Type
S503-DIG
Base unit - S503, including 7 user-specified port adapters, power adapter, desiccant and adapter tool
S503-DIG-OPT
Base unit -Calibration kit with Optidew adapters - S503, with 5 user-specified port adapters, 2 Optidew adapters
(A000272 and A000273), power adapter, desiccant and adapter tool
S503-DIG-SET
Base unit -Calibration kit - S503, including hand meter and probe (with calibration certificate), 7 user-specified port
adapters, power adapter, desiccant, distilled water bottle (water not included), adapter tool and carrying case
S503-12
Port adapter 12mm (0.47")
S503-13.5
Port adapter 13.5mm (0.53")
S503-14
Port adapter 14mm (0.55")
S503-15
Port adapter 15mm (0.59")
S503-18.5
Port adapter 18.5mm (0.73")
S503-19
Port adapter 19mm (0.75")
S503-24
Port adapter 24mm (0.94")
S503-25
Port adapter 25mm (0.98")
S503-AUS
Australian power supply
S503-EUR
European power supply
S503-NA
North American power supply
S503-UK
UK power supply
S503-C
Display in deg C
S503-F
Display in deg F
Adapter
Power
Display
© Michell Instruments 2009-2011
60
Calibration
S503
Humidity and Dew-Point Instruments
Calibration
S904
Relative Humidity and Temperature Generator for Calibrations
Technical Specifications
Humidity
Generator range
10–90% RH
Accuracy
Control element
≤±1% RH (10–70% RH)
≤±1.5% RH (70–90% RH)
Stability
±0.2% RH (20–80% RH)
Temperature
Generator range
+10 to +50°C (+50 to +122°F)
(lowest T set point = 10ºC (50ºF) below ambient)
Accuracy
±0.1°C (±0.02°F)
Stability
±0.1°C (±0.02°F)
Chamber
Ramp rate from
20 to 40°C (68 to 104°F)
40 to 20°C (104 to 68°F)
1.5°C / minute (2.7°F) / minute
0.7°C / minute (1.2°F) / minute
Control element
Removable relative humidity sensor
General
The S904 humidity and temperature generator is designed to
calibrate and verify the operation of relative humidity sensors
and transmitters. With a chamber temperature range of 10
to 50°C (50 to 122°F), a uniformity of ±0.1°C (0.02°F) and
the ability to generate 10–90% RH, accurate and repeatable
calibrations are made easy.
Probe ports
up to 5 – sensor body diameters 5–25mm (0.2 to
0.98”) accommodated by port adapters
Chamber volume
2000cm3 (122.1in3)
Chamber dimensions
105 x 105 x 160mm (4.13 x 4.13 x 6.3”)
(wxhxd)
Instrument dimensions
520 x 290 x 420mm (20.5 x 11.4 x 16.5”)
(wxhxd)
Set point resolution
0.1 for humidity and temperature
Highlights
Displays
3 digit LED, 10mm (0.39”) characters
• Relative humidity and temperature controlled chamber
Supply
85–264 V AC, 47–63 Hz, 150 VA
Weight
20kg (44lb)
• Excellent stability within chamber: ±0.2% RH,
Temp. ±0.1°C (0.02°F)
• Optional in-built data-logging for reference probe and probes under calibration
• Probes with body diameters between 5 to 25mm (0.2 to
0.98”) can be accepted
Dimensions
Issue No: S904_97200_V2_UK_1110
61
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories and Spare Parts
0.25kg (0.55lbs) desiccant (orange)
A000171
ø18.5mm (0.73") Blind stop
A000200
Drying module
A000240
Water bottle
A000242
Door kit with 5 ports. 5 adapters to be specified
A000263
Door kit with 5 ports and 25 adapters (5 x ø19mm (0.75"), 4
x ø12mm (0.47"), ø13.5mm (0.53"), ø15mm (0.59"), ø18.5mm
(0.73"), ø24mm (0.94") - and blind stops. Adapter tool included)
A000264
Tool for changing the port adapters
A000265
Door with clear window - no ports
A000266
Door without ports
A000268
Door kit for use with MI Optidew. (Optidew dew-point sensor
port adapter, PRT port adapter and 4 x ø19mm (0.75") adapters.
Adapter tool included)
A000269
Polymer port adpt ø18.5mm (0.73") to ø3mm (0.19") (for Optidew
probe)
A000273
Blind stop for Optidew adapter
A000277
Blind stop for PRT adapter
A000278
M30x1 Molded polymer port adpt & blind stop (to be modified by
customer)
A000290
Polymer port adpt ø client specific & blind stop
A000290X
Polymer port adpt for ø12mm (0.47") probe, blind stop (M30x1)
A000291
Polymer port adpt for ø13.5mm (0.53") probe, blind stop (M30x1)
A000292
Polymer port adpt for ø14mm (0.55") probe, blind stop (M30x1)
A000293
Polymer port adpt for ø15mm (0.59") probe, blind stop (M30x1)
A000294
Polymer port adpt for ø18.5mm (0.73") probe, blind stop (M30x1)
A000295
Polymer port adpt for ø19mm (0.75") probe, blind stop (M30x1)
A000296
Polymer port adpt for ø24mm (0.95") probe, blind stop (M30x1)
A000297
Polymer port adpt for ø25mm (0.98") probe, blind stop (M30x1)
A000298
Transport Case for OptiCal and S904
OCAL-TC
Control sensor
HT961T00
1.
2.
3.
4.
5.
6.
7.
8.
S904 set point temperature (0-10 V = 0 to 100°C (32 to 212°F)
S904 set point RH (0-10 V = 0 to 100% RH)
Free to use (0-10 V)
Free to use (0-10 V)
Free to use (0-10 V)
Free to use (0-10 V)
Free to use (0-10 V)
Free to use (0-10 V)
The acquisition system only measures 0-10 V on every channel so the 4-20 mA
signals from the Optidew are converted to a 0-10 V signal. Channels 1 and 2 are
not available for logging signals. A 500 Ω resistor must be used.
Labview logging software
Order Codes
S904 - Relative Humidity and Temperature Generator for Calibrations
Feature
Item
Description
Type
S904
Base unit
S904-D
Base unit - with RS232/USB interface (data-logging software for PC - 6 channel data-logger)
© Michell Instruments 2009-2011
62
Calibration
S904
Humidity and Dew-Point Instruments
Calibration
OptiCal
Relative Humidity and Temperature Generator with built-in Chilled Mirror
Reference
Technical Specifications
Reference Hygrometer
Type
Optidew chilled mirror dew-point
transmitter
Humidity
Generator range
10–90% RH
Accuracy
Control element
≤±1% RH (10–70% RH)
≤±1.5% RH (70–90% RH)
Stability
±0.2% RH (20–80% RH)
Temperature
Generator range
+10 to +50°C (+50 to +122°F)
(lowest T set point = 10ºC (18°F) below
ambient)
Accuracy
±0.1°C (±0.02°F)
Stability
±0.1°C (±0.02°F)
Chamber
Ramp rate from
20 to +40°C (68 to 104°F)
40 to 20°C (104 to 68°F)
1.5°C / minute (2.7°F) / minute
0.7°C / minute (1.2°F) / minute
The OptiCal is a bench-top, fully self-contained humidity/
temperature calibrator. The system comprises a humidity
and temperature controlled chamber that can house up
to five or more humidity sensors, depending on their
physical dimensions. The humidity and temperature within
the chamber are closed-loop controlled and continuously
monitored by a precision chilled mirror reference hygrometer.
The OptiCal works by time-proportioning the flows of dry and
saturated air according to the pre-selected relative humidity
value. The chamber temperature is controlled by a four-zone
Peltier heat pump arrangement for maximum stability and
minimum temperature gradient. The saturator assembly
can be filled easily with the distilled water reservoir at the
front of the unit and the easily accessible desiccator can be
re-charged by heating when required. No other maintenance
is necessary. The only external service required is a single
phase power supply.
Control element
Removable relative humidity sensor
Outputs
Analog
Digital
Alarm
Two channels 4-20 mA or 0-20 mA
RS232 (RS485 optional)
Volt free contact, 2A @ 30 V DC
Highlights
Supply
85–264 V AC, 47–63 Hz, 150 VA
Weight
20kg (44lb)
General
• Precision relative humidity and temperature calibrator
Probe ports
up to 5 – sensor body diameters 5–25mm (0.2
to 0.98”) accommodated by port adapters
Chamber volume
2000 cm3 (122.1in3)
Chamber dimensions
105 x 105 x 160mm (4.13 x 4.13 x 6.3”)
(wxhxd)
Instrument dimensions
520 x 290 x 420mm (20.5 x 11.4 x 16.5”)
(wxhxd)
Set point resolution
0.1 for humidity and temperature
Displays
High definition 2 lines alpha numeric
Measurement units
ºC, ºCdp, % RH
g/kg, g/m3, (t-td), aw
• Generate 10 to 90% RH over 10 to 50°C (50 to 122°F)
temperature
• Integral chilled mirror reference hygrometer
• Humidity and temperature profile generation for
unattended verification of sensors
• Transportable calibrator enables on-site calibrations
Logging and profiling software
Issue No: OptiCal_97161_V2_UK_1110
63
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories and Spare Parts
0.25kg (0.55lbs) desiccant (orange)
A000171
ø18.5mm (0.73") Blind stop
A000200
Drying module
A000240
Water bottle
A000242
PRT sensor
A000243
Door kit with 5 ports. 5 adapters to be specified
A000263
Door kit with 5 ports and 25 adapters (5 x ø19mm (0.75"), 4
x ø12mm (0.47"), ø13.5mm (0.53"), ø15mm (0.59"), ø18.5mm
(0.73"), ø24mm (0.94") - and blind stops. Adapter tool included)
A000264
Tool for changing the port adapters
A000265
Door with clear window - no ports
A000266
Door without ports
A000268
Door kit for use with MI Optidew. (Optidew dew-point sensor
port adapter, PRT port adapter and 4 x ø19mm (0.75") adapters.
Adapter tool included)
A000269
Polymer port adpt ø18.5mm (0.73") to ø3mm (0.19") (for
Optidew probe)
A000273
M30x1 Molded polymer port adpt & blind stop (to be modified by
customer)
A000290
Polymer port adpt ø client specific & blind stop
A000290X
Polymer port adpt for ø12mm (0.47") probe, blind stop (M30x1)
A000291
Polymer port adpt for ø13.5mm (0.53") probe, blind stop (M30x1)
A000292
Polymer port adpt for ø14mm (0.55") probe, blind stop (M30x1)
A000293
Polymer port adpt for ø15mm (0.59") probe, blind stop (M30x1)
A000294
Polymer port adpt for ø18.5mm (0.73") probe, blind stop (M30x1)
A000295
Polymer port adpt for ø19mm (0.75") probe, blind stop (M30x1)
A000296
Polymer port adpt for ø24mm (0.95") probe, blind stop (M30x1)
A000297
Polymer port adpt for ø25mm (0.98") probe, blind stop (M30x1)
A000298
Control sensor
HT961T00
Transport Case for OptiCal and S904
OCAL-TC
DimensionsChamber
Chamber
Dimensions
Dimensions
200mm
200mm
(7.87")(7.87")
110mm
110mm
(4.33")(4.33")
104mm
104mm
(4.09")(4.09")
124mm
124mm
(4.88")(4.88")
(16.53")
420mm420mm
(16.53")
290mm290mm
(11.41")
(11.41")
Side View
Side View
520mm (20.47")



 
 
 

 














Front View
OFF
ON
REMOTE COMMS
OPTICS ADJUST


Rear View
Order Codes
OPTICAL - Precision humidity calibration system with temperature control. Includes 5 port door and integrated chilled mirror reference
hygrometer with 3 point UKAS RH calibration
Feature
Item
Description
Base Model
OPTICAL-BASE
Base unit
© Michell Instruments 2009-2011
64
Calibration
OptiCal
Humidity and Dew-Point Instruments
Calibration
Control Kit
For the Calibration of Relative Humidity Sensors
Technical Specifications
The control kit consists of:
• 5 phials of the same humidity value
• 7 test strips
• 1 control chamber with version HKCxxC,
without control chamber with version HKCxxS
• Box dimensions: 100 x 140 x 40mm (3.93 x 5.51 x 1.57”)
• Weight: 0.15kg (0.33lb)
Accuracy
An accuracy of ±3% RH can be achieved if the test procedure is
adhered to.
Operating Conditions
• Reference temperature: +23°C ±1°C (+73°F ±1.8°F)
• Environmental humidity stabilized ±10%
• Set up conditions:
Temperature between 0 and +50°C (+32 and +122°F) with
correction to be applied according to the instruction m
anual.
Humidity between 40 and 60% RH
• The instrumentation should be checked and the control kit
must be kept in the same environment at least 10 hours
before the procedure is started
• Shelf life of the solutions:
In phial: unlimited
In the control chamber: 2 hours
Ordering Example
HKC-25-C12
25% RH control kit with chamber & ø12mm (0.47”) adapter, including transport case
Order Codes
HKC - Control Kit for Relative Humidity with transport case
Feature
Item
Description
Base Model
HKC
Base unit
RH Level
HKC-25
25% RH without chamber
HKC-35
35% RH without chamber
HKC-50
50% RH without chamber
HKC-80
80% RH without chamber
HKC-C12
With chamber & ø12mm (0.47") adapter
HKC-C19
With chamber & ø19mm (0.47") adapter
HKC-C22
With chamber & ø22mm (0.47") adapter
HKC-S00
Without chamber
Chamber
Issue No: Control Kit_97164_V2_UK_1110
65
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Effects of pressure, temperature and
concentration on humidity
parameters
In nature, water exists in three different states: gaseous
(vapor), liquid (rain, fog) and solid (snow, ice, hail). Water in
the gaseous state is invisible. The maximum quantity of water
vapor that the air can contain depends on temperature and
pressure. The table below shows how the parameter change
influences the measured values.
Relative humidity is the ratio of the actual quantity of water
vapor that an air sample contains to the maximum quantity
of water vapor that such a sample can contain at the sample
pressure and temperature.
Temperature
Increase
% RH
Dew Point
Temperature
Decrease
Pressure
Increase
Pressure
Decrease
Vapor
Increase
Vapor
Decrease












Absolute Humidity






Mix Ratio






Concentration of Water Vapor






© Michell Instruments 2009-2011
66
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000001
19mm (0.75”) Slotted
protection cap white
WM33 & 52
A000022
12mm (0.47”) Mesh filter with
protection cap, black
PCMini52
A000002
19mm (0.75”) Slotted
protection cap black
PC33, 52, 62 & 62V
DT722
A000023
12mm (0.47”) Flat SS sintered
dust filter
PCMini52
A000003
12mm (0.47”) Slotted
protection cap, black
PCMini52
A000025
19mm (0.75”) Arrow SS
sintered filter 5μm
A000026
19mm (0.75”) Arrow SS
sintered filter 10μm
PC33, 52, 62 & 62V
WM33 & 52
DT722
A000014
19mm (0.75”) PVDF filter
PC33, 52, 62 & 62V
WM33 & 52
DT722
A000027
19mm (0.75”) Arrow SS
sintered filter 20μm
PC33, 52, 62 & 62V
WM33 & 52
DT722
A000015
19mm (0.75”) PVDF filter with
protection cap black
PC33, 52, 62 & 62V
DT722
A000028
12mm (0.47”) Arrow 20 μm SS
sintered filter
PCMini52
A000016
19mm (0.75”) PVDF filter with
protection cap white
WM33 & 52
A000040
19mm (0.75”) Foil filter 2μm
with protection cap black
PC33, 52, 62 & 62V
DT722
A000017
12mm (0.47”) PVDF filter
PCMini52
A000041
19mm (0.75”) Foil filter 2μm
with protection cap white
WM33 & 52
A000018
12mm (0.47”) PVDF filter with
protection cap, black
PCMini52
A000042
Oleophobic foil filter 0.7μm with
protection cap black
PC33, 52, 62 & 62V
DT722
A000019
HDPE filter
SF52
A000043
Oleophobic foil filter 0.7μm with
protection cap white
WM33 & 52
A000021
19mm (0.75”) Mesh filter with
protection cap black
PC33, 52, 62 & 62V
WM33 & 52
DT722
A000044
19mm (0.75”) Foil filter 1.5µm
w/protection cap black
PC33, 52, 62 & 62V
DT722
67
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000045
19mm (0.75”) Foil filter
1.5μm with protection cap
white
WM33 & 52
K9
PEEK protection cap with SS
mesh filter
WR283
WR293
DT284
H2
SS sintered filter
WM281
WM291
DT282
SSG
SS sintered guard
replacement
Easidew
Easidew I.S.
Easidew PRO I.S.
Easidew Online
H3
SS sintered filter
WR283
WR293
DT284
Z1
SS cap slotted with PTFE filter
PCMini70
PFMini72
WR285
H4
SS sintered filter
PF211
DT269
Z2
ABS cap slotted with PTFE
filter, white
DT269
PF211
J2
SS sintered filter with teflon
coating
WM281
WM291
DT282
Z6
SS cap slotted with PTFE filter
DT282
J3
SS sintered filter with teflon
coating
WR283
WR293
DT284
Z7
Delrin cap slotted with PTFE
filter, white
WM281
WM291
K1
SS cap slotted with mesh
filter
PCMini70
PFMini72
WR285
EA2-HDPE
Pack of 10 replacement HDPE
guards.
(For protection against fine
particulate (<10µm))
Easidew
Easidew I.S.
Easidew PRO I.S.
Easidew Online
K6
AISI 316 cap slotted with SS
mesh filter
DT282
I7-0-00-0
Hygrosmart without Pt100
output
PCMini70
PFMini72
DT269
K7
Delrin cap slotted with SS
mesh filter
WM281
WM291
I7-0-00-1
Hygrosmart with Pt100 output
(RH = 0-1 V)
PCMini70
PFMini72
WM281
WM291
DT269/DT282
PF211 (V)
K8
SS mesh filter
WR283
WR293
DT284
I7-4-00-1
Hygrosmart with Pt100 output
(RH = 0.2-1 V)
PF211 (mA)
© Michell Instruments 2009-2011
68
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
A000030
19mm (0.75”) Connector, no
cable, with screw terminals
PC33, 52,
62 & 62V
DT722
A000030XM
19mm (0.75”) Connector, with
cable (customer spec length)
PC33, 52,
62 & 62V
DT722
A000031
19mm (0.75”) Connector with 2m
(6.5’) cable
PC33, 52,
62 & 62V
DT722
A000032
19mm (0.75”) Connector with 5m
(16’) cable
PC33, 52,
62 & 62V
DT722
A000033
12mm (0.47”) Connector with 2m
(6.5’) cable
PCMini52
A000036
12mm (0.47”) Connector with 5m
(16’) cable
PCMini52
A000037
12mm (0.47”) Connector with
10m (33’) cable
PCMini52
A000321
12mm (0.47”) Connector without
cable (with solder terminals)
PCMini52
A000321XM
12mm (0.47”) Connector with
cable (customer spec length)
PCMini52
A000322
12mm (0.47”) Connector with
20m (25.6’) cable
PCMini52
69
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000100
3/4” NPT SS adj. fitting for SS
probes
PC33, 52,
62 & 62V
DT722
1A01210
Mini flange
I7000
I7400
A000101
1/2” NPT SS adj fitting for SS
probe. Only to be used with SS
probe housing
PCMini52
2510367
Mounting clip
PFMini72
A000110
Al mounting flange for ø19mm
(0.75”) SS probes (outside
ø80mm (3.15”))
PC33, 52,
62 & 62V
DT722
2510387
Mounting clip
PF211
A000111
Aluminum mounting flange for
ø12.0mm (ø0.47”) SS probes
(outside ø40.0mm (ø 1.57”)). To
be used with SS probes
PCMini52
3420085
Fixing collar
PF211
A000120
ø90mm (3.54”) WM weather
prot. cap
(in combination with A000111 for
ø12mm (0.47”) probes)
PC33, 52, 62
& 62V
PCMini52
3401135
Molded polymer fitting
PF211
A000125
ø120mm (4.72”) WM weather
prot. cap
(in combination with A000111 for
ø12mm (0.47”) probes)
PC33, 52, 62
& 62V
PCMini52
6A05130
Connecting kit for PCB
I7000
I7400
A000150
Mini flange for ø19.0mm (ø0.75”)
molded polymer probe
PC33, 52,
62 & 62V
6A06350
Connecting kit with wires
I7000
I7400
A000340
Bonded seal, (DIN ISO 228)
G½” (BSP)
SF52
FLA012
Al mounting flange for ø12mm
(0.47”) SS probes
DT262
DT284
WR283
WR293
FLA019
Al mounting flange for ø19mm
(0.75”) SS probes
DT269
DT282
© Michell Instruments 2009-2011
70
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
EA2-CK
Easidew communications kit
for EA2 - Enables connection
to Easidew Transmitter and
re-ranging & reconfiguration
of output via configuration
software
Easidew
Easidew I.S.
Easidew PRO I.S.
Easidew Online
F035263
USB cable/software for
configuration
WM281, WM291
DT282, DT284
WR283, WR285
WR293,
330185
RS422/485 to PC (RS232)
converter
WM281, WM291
DT282, DT284
WR283, WR285
WR293,
GI-PF-01
Easidew PRO I.S.
Easidew I.S.
KFD0-CS-EX1.50P galvanic
isolator (for Easidew PRO I.S. Pepperl & Fuchs)
71
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
A000350
Sample block without filter
SF52
A000351
Sample block with filter
SF52
EA2-SAM
Easidew Sampler
SS block w/filter cartridge
(0.3µm), inlet/outlet push ftgs,
m-valve & PTFE vent tube
(6mm (0.24”)), mtg bracket
Easidew
Easidew I.S.
Easidew PRO I.S.
Easidew Online
CSB
SS sample block (5/8” UNF
thread with 1/8” NPT ports)
Easidew
Easidew I.S.
Easidew PRO I.S.
Easidew Online
© Michell Instruments 2009-2011
72
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000180
ø18.5mm (0.73”) molded polymer
port adpt (for ø8mm (0.31”) probes)
S503
A000273
Polymer port adpt ø18.5mm (0.73”)
to ø3mm (0.19”) (for Optidew
probe)
S904
S503
OptiCal
A000200
Blind stop ø18.5mm (ø0.73”)
S904
OptiCal
A000277
Blind stop for Optidew adapter
S503
S904
A000263
Door kit with 5 ports. 5 adapters to
be specified
S904
OptiCal
A000278
Blind stop for PRT adapter
S503
S904
A000264
Door kit with 5 ports and 25 adapters
(5 x ø19mm (0.75”), 4 x ø12mm
(0.47”), ø13.5mm (0.53”), ø15mm
(0.59”), ø18.5mm (0.73”), ø24mm
(0.94”) - and blind stops. Adapter
tool included)
S904
OptiCal
A000280
Al adapter & blind stop (to be
modified by customer) (M30x1)
S503
A000266
Door with clear window - no ports
S904
OptiCal
A000280X
Al port adapter ø client specific &
blind stop (M30x1)
S503
A000268
Door without ports
S904
OptiCal
A000281
Al port adpt for ø12mm (0.47”)
probe, blind stop (M30x1)
S503
A000269
Door kit for use with MI Optidew.
(Optidew dew-point sensor port
adapter, PRT port adapter and 4 x
ø19mm (0.75”) adapters. Adapter
tool included)
S904
OptiCal
A000282
Al port adpt for ø13.5mm (0.53”)
probe, blind stop (M30x1)
S503
A000272
SS port adapter for Optidew
S503
A000283
Al port adpt for ø14mm (0.55”)
probe, blind stop (M30x1)
S503
A000190
ø18.5mm (0.73”) molded polymer
port adpt (for ø12mm (0.47”) probes)
73
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000284
Al port adpt for ø15mm (0.59”)
probe, blind stop (M30x1)
S503
A000292
Polymer port adpt for ø13.5mm
(0.53”) probe, blind stop (M30x1)
S904
OptiCal
A000285
Al port adpt for ø18.5mm (0.73”)
probe, blind stop (M30x1)
S503
A000293
Polymer port adpt for ø14mm (0.55”)
probe, blind stop (M30x1)
S904
OptiCal
A000286
Al port adpt for ø19mm (0.75”)
probe, blind stop (M30x1)
S503
A000294
Polymer port adpt for ø15mm (0.59”)
probe, blind stop (M30x1)
S904
OptiCal
A000287
Al port adpt for ø24mm (0.95”)
probe, blind stop (M30x1)
S503
A000295
Polymer port adpt for ø18.5mm
(0.73”) probe, blind stop (M30x1)
S904
OptiCal
A000288
Al port adpt for ø25mm (0.98”)
probe, blind stop (M30x1)
S503
A000296
Polymer port adpt for ø19mm (0.75”)
probe, blind stop (M30x1)
S904
OptiCal
A000290
M30x1 Molded polymer port adpt
& blind stop (to be modified by
customer)
S904
OptiCal
A000297
Polymer port adpt for ø24mm (0.95”)
probe, blind stop (M30x1)
S904
OptiCal
A000290X
Polymer port adpt ø client specific &
blind stop
S904
OptiCal
A000298
Polymer port adpt for ø25mm (0.98”)
probe, blind stop (M30x1)
S904
OptiCal
A000291
Polymer port adpt for ø12mm
(0.47”) probe, blind stop (M30x1)
S904
OptiCal
© Michell Instruments 2009-2011
74
Humidity and Dew-Point Instruments
Accessories
Item
Associated
products
Item
Associated
products
A000171
0.25 kg (0.55lbs) desiccant
(orange)
S503
S904
OCAL-TC
Transport Case for OptiCal
Optical
A000230
Carrying case for the S503
S503
OPT-V-01
Optidew vision reference
hygrometer with sensor
S503
A000240
Drying module
S904
OptiCal
A000242
Water bottle
S503
S904
A000243
PRT sensor
S904
OptiCal
A000265
Tool for changing the
aluminum port adapters
S503
S904
HT961T00
Control sensor
S904
OptiCal
HX757
Control sensor
S503
75
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Applications for Humidity Sensors
Michell humidity sensors are used in hundreds of applications, including:
Agriculture
• Agricultural and Crop Research
• Agrochemical
• Environmental Testing
• Poultry/Meat/Egg/Dairy
• Greenhouses
Aerospace
• MIL Spec Welding
• Cabin Environment
• Environmental Testing
• Coatings
• Parts Storage
• Space Purge Systems
• Weather Monitoring
Automotive
• HVAC Manufacturing
• Dynamometer/Engine Test Cells
• Paint Booths
• In-Vehicle Air Quality
• Environmental Testing
• Metrology – Cal Lab
• Maintenance Alarms
• Compressed Air Dew Point
Bricks/Ceramics
• Ceramic Greenware Drying
• Product Quality
• Glaze Application
• Environmental Testing
• Concrete Curing
Chemical/Petroleum
• Polymerization
• Raw Material Testing and Storage
• Manufacturing Drying Processes
• Optimizing Production Costs
• Intermediates Storage
• Environmental Conditions
• Natural Gas Quality
• Environmental Testing
Coatings
• Powder Coating
• Adhesive Curing
• Adhesive Tape
• Application Test
• Maintenance Alarms
• Environmental Testing
© Michell Instruments 2009-2011
Atmospheric
• Environmental Research
• Snowmaking Machines
• Soil Moisture
• Plant Growth Chambers
• Climatology
• Hydrometeorology
Environmental Chamber
• Electronics Test
• Climatic Stability Evaluation
• Product Testing on Animals
• Plant Growth Chambers
• Equipment Cabinet
Food/Beverage
• CO2 Drying
• Drying Process
• Energy cost savings
• Environmental Testing
Fuel Cell
• Manufacturing
• Testing
• Fuel Monitoring
• Maintenance Alarms
Healthcare
• Stop Contamination
• Dental Casting Formulation
• Pill Coating
• Extend Shelf Life
• Environmental Testing
• Respiratory Therapy
High Tech
• Optical Coating
• Waveguide Pressurization
• Maintenance Alarms
HVAC
• Indoor Swimming Pool
• Control
• Climate Control
• Energy Use
• BMS, DCV and IAQ
• Hazardous Locations
• Outdoor Measurement
Industrial Applications
• Heat Treating
• Welding Hoods
• Adhesives
• Maintenance Alarms
• Environmental Testing
76
Humidity and Dew-Point Instruments
Applications
Leather/Textile
• Dyeing/Printing
• Process Control
• Product Quality
• Storage & Transportation
• Maintenance Alarms
Marine
• Inert Gas Systems
• Lubrication Oil Monitoring
• Weather Observation
• Maintenance Alarms
Metallurgy
• Furnace Gas
• Lubrication and Quench Oil
• Dry Air Storage
• Sintering Furnace
• Maintenance Alarms
• Environmental Testing
Meteorology
• Professional Forecasting
• Agricultural and Forest
• Emergency Management
• Fire Hazard Warning
• Airport Weather monitoring
• Road and Rail Weather
Metrology
• Direct Calibration
• Indirect Calibration
• HVAC
• Standards Storage
Military
• Vehicle Air Quality
• Dry Air Storage
• Drive-in Chambers
• Weapons Test Chambers
• Torpedo Environmental testing
• Rocket Environmental testing
• Maintenance Alarms
• Environmental Testing
Museums
• Artifact Storage and Display
• Transportation
• HVAC
• Maintenance Alarms
Nuclear
• Containment vessel
• Dry Air Storage
• Assembly/Disassembly
• Encapsulation Research
• Maintenance Alarms
Packaging
• Product Storage
• Printing Labelling
• Development
• Environmental Testing
Paint
• Long Term Testing Outdoors
• Water Based Paint Booths
• Solvent Based Paint Booth
• Accelerated Life Testing
• Maintenance
Paper
• Process Air Exiting Hood
• Compressed Air
• Conversion/Storage Rooms
• Lubrication Oil
• Roof Protection
• Storage
• Distribution
• Pad Air/Gas
• Quality Control
Pharmaceutical
• Bioreactors
• Clean Rooms
• Compressed Air
• Incubators
• Stability Testing
• Packaging
• Storage & Transportation
• Production Areas
• Animal Test Facilities
• Tablet Coating
• Environmental Testing
Molded polymers
• Blow Molding PET
• Compressed Air
• Hopper Humidity
• HVAC – Manufacturing
• Extrusion
• Blown Film
• Printing & Labelling
• Pellet Storage
• Production Area
• Product Storage
• Injection Mold Preparation
• Shipping & Supply Chain
77
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
Applications
Power/Energy
• Dew Point in SF6
• Compressed Air
• Gas Turbine Inlet Air
• Lubrication Oil
• H2 Cooling Loop
• Bag Houses
• Transformer Maintenance
• Maintenance Alarms
Process
• Monitor Environments
• Adhesives
• Prevent Corrosion
• Prevent Contamination
• Preserve Texture
• Conserve Energy
• Environmental Testing
Rubber
• Natural Rubber Storage
• Tire Cord Storage
• Maintenance Alarms
Semi Conductor
• Clean Rooms
• Compressed Air
• Environmental Compensations
• Glove Boxes
• Lithium Battery Manufacturing
• Environmental Chambers
• Photo Resist Operations
• IC Packaging
• PCB Manufacturing
• Extended Life Testing
Storage
• Warehousing
• Museums
• Movement of Goods
• Container Testing
• Wine Barrel
• Fruit
Tobacco
• Tobacco Conditioning
• Cigarette Making
• Packaging
• Storage & Transportation
• Maintenance Alarms © Michell Instruments 2009-2011
Transportation
• Containers
• Storage
• Shipping
• Live Animal Shipments
• Cabin Monitoring
• Bulk Products
• Highway Icing
• Airport Weather
Wood
• Kiln Drying
• Laminates/By-product Drying
• Dry Air Storage
• Adhesive Research
78
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
The following text is reproduced with kind permission
from the National Physical Laboratory. It was originally
published in a booklet, A Guide to the Measurement of
Humidity.
1
At any particular temperature, air that contains its full
capacity of water vapour, is said to be ‘saturated’. The
‘relative humidity’ of the air expresses how fully saturated
it is with water vapour. A variety of other (‘absolute’)
measures are used to express how much water vapour is
actually present (irrespective of temperature or level of
saturation).
What is humidity?
The word ‘humidity’ denotes the presence of water
vapour in air or other gases. Water vapour is the gaseous
form of water, and can be thought of much like any other
kind of gas. It is normally transparent, and makes up
about one hundredth (or one percent) of the air around
us.
Definition and explanations of the most important of
these terms are given in the next Section.
1.1 Humidity terms and definitions
Some vocabulary specific-to-humidity and other common
words with specialised meanings in this context are as
follows:
Humidity arises in practice because, in the same way that
hot water gives off steam, so water at lower temperatures
– including ice – also gives off water vapour. Wherever
there is water or ice, there is evaporation (or its opposite,
condensation). The extent to which this happens depends
upon a number of factors, the most important of which
is temperature. Similarly, other liquid or solid materials
– most of which have some water content – will give off
(or sometimes soak up) water vapour. Of course, water
vapour can also be found in places where there is no
liquid or solid nearby, for example in remote parts of the
Earth’s atmosphere.
Absorption (of water vapour) – retention (of water
vapour) by penetration into the bulk of a material
Adsorption (of water vapour) – retention (of water
vapour) as a surface layer on a material
Condensate – condensed material, e.g. liquid water or
ice
Desorption – release of adsorbed or absorbed substance
Air (or empty space, or any other gas) has a given
capacity to absorb water vapour. This capacity depends
mainly on temperature. Generally speaking, the hotter
the air, the more water vapour it can hold. The graph in
Figure 1 illustrates this.
Desiccant – any substance which exerts a drying action
by chemically absorbing water vapour
Dry-bulb temperature – measured air temperature,
usually paired with a ‘wet-bulb’ temperature to derive a
value of relative humidity
Humidity – the presence of water vapour in air or
other gas. Some people use ‘humidity’ to mean relative
humidity only. Strictly speaking, ‘humidity’ also refers to
all kinds of absolute indications of humidity. For very low
humidity, other more specific terms, tend to be used
Hygrometer – any instrument for measuring humidity
Hygrometry – the subject of humidity measurement
Hygroscopic – tending to absorb water vapour
Inert gas – chemically non-reactive gas, such as
nitrogen, helium, argon, etc
Moisture – commonly used to refer to liquid water or
water vapour in any form, ‘moisture’ is also the term
particularly used to mean water that is absorbed or
bound into any material
Figure 1. Saturation vapour pressure of water increases with temperature
79
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
Probe – the part of an instrument that houses the
sensor remotely from the main body of the instrument,
e.g. at the end of a connecting electrical lead. In some
situations the word ‘probe’ may be used to refer to an
entire hygrometer. Also loosely used interchangeably with
‘sensor’ and ‘transmitter’. ‘Probe’ may also refer to a tube
used to extract gas for measurement.
Sensor – the active or sensing part of a measuring
instrument. There are some cases where a whole
hygrometer is referred to as a ‘sensor’. Also loosely used
interchangeably with ‘probe’ and ‘transmitter’.
Transmitter – instrument which normally gives an
electrical output (analog or digital) rather than a
displayed result. The sensing head may be an integral
part of the transmitter or may be connected via an
external cable. Also loosely used interchangeably with
‘probe’ and ‘sensor’.
Wet-bulb temperature – temperature indicated by a
thermometer sheathed in wet wicking, and influenced by
the rate of evaporation from the wicking. Usually paired
with a ‘dry-bulb’ temperature to derive a value of relative
humidity.
1.2 Definitions of measured quantities
Many of the following definitions are based on those
in the British Standard BS 1339: 1965 (confirmed
1981, under revision in 1996), ‘Definitions, formulae
and constants relating to the humidity of the air’. As
given below, the definitions are explanatory rather than
rigorous. For rigorous definitions, BS 1339 should be
consulted. In practice, the usage of some terms varies
according to the context: for example the terms in the
field of air-conditioning are sometimes different from the
terms used in meteorology for the same quantities. In
each case a preferred term is given below, but qualifying
notes indicate where there are common alternatives in
use.
Units of measurement for expressing the quantities are
given, and may have alternative forms, e.g. ‘grams per
cubic metre’ is given by ‘g m-3’, alternatively written
‘g/m-3’.
Absolute humidity – The mass of water vapour present
in unit volume of moist air of a given temperature and
pressure. SI (metric) units are grams of water per cubic
metre of air (g m-3). Older references may be in terms of
pounds per million cubic feet (lb10-6ft-3) or in grains per
cubic foot (gr ft-3). (One grain 0.0648 gram.).
© Michell Instruments 2009-2011
NOTE: In chemical engineering the preferred term for
this concept is ‘volumetric absolute humidity’, while
‘absolute humidity’ is used to denote the quantity referred
to in this document as ‘mixing ratio’. In meteorology the
preferred term is ‘vapour concentration’. Other terms such
as ‘vapour density’, ‘mass concentration’ and ‘moisture
content by volume’ are also sometimes used to mean the
same thing.
USAGE: It is important not to confuse the particular
quantity ‘absolute humidity’ with the general category of
‘absolute measurements of humidity’.
Dew point (or dew-point temperature) – The
temperature at which dew, or condensation, forms,
on cooling a gas. This is, in effect, the temperature at
which air becomes saturated in equilibrium with water.
Expressed in degrees Celsius (°C) or occasionally in other
units of temperature (e.g. in degrees Fahrenheit (°F) in
USA). See also frost point.
USAGE: Negative dew points, with respect to supercooled water below 0°C, are always shown with a minus
(-) sign. Where there is any risk of ambiguity, a plus (+)
sign may also be used for positive dew points:
e.g. ‘a range of dew points between -5 °C and +5 °C’
The term ‘dew point’ is often used generally to include
‘frost point’ (sec below). However in the range just below
0 °C, where either frost or dew (super-cooled water) can
form, the values of dew point and frost point differ.
The use of initials (e.g. ‘dp’) is not a recognized
abbreviation, but it occurs widely, and is used to
distinguish clearly between dew-point temperatures and
other values of (air) temperature. For example a dewpoint value might be expressed in the form ‘1.0°C dp’
Enthalpy (of humid gas) – Measure of the total
energy in a humid gas. Enthalpy is a function of the gas
temperature and pressure, and of the moisture content,
since water absorbs energy on changing from condensed
state to vapour. Enthalpy is a useful concept in air
conditioning, where it is important to know how much of
the ‘stored’ energy will be consumed, or released, when
the temperature or water content is raised, or lowered.
Enthalpy of a gas can be defined as the sum of ‘sensible’
and ‘latent’ heat for each component in the gas. (See
below for definitions of sensible heat and latent heat.)
Values of enthalpy are conventionally expressed relative
to a datum point (i.e. a zero or base line). For a dry gas,
this is normally the heat content at 0°C. For water vapour,
the enthalpy is usually expressed relative to the heat
content of liquid water at 0.01°C.
80
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
NOTE: When the mole is used, the elementary entities
must be specified as atoms, molecules, etc.
Expressed in terms of energy per quantity of dry gas,
i.e. kilojoules per kilogram (kJ kg-1) (or other units, for
example British thermal units per pound, Btu/lb).
Mole fraction – The mole fraction of a component is the
ratio of the amount (number of moles) of that component
to the total amount of substance present. Expressed as a
dimensionless ratio.
Equilibrium relative humidity (ERH) (over a
substance) – The value of relative humidity of the air,
at which there is no net exchange of moisture with any
nearby substance. This is used for indirectly indicating or
controlling the condition of moisture-sensitive substances
such as paper. Expressed as a percentage (%). (See also
water activity.)
Partial pressure (of water vapour) – The part of the
overall pressure exerted by the water vapour component
in a gas. Expressed in units of pressure such as pascals
(Pa) or in multiples; kilopascals (kPa) or megapascals
(MPa), with non-SI alternatives such as millibar (mbar)
or millimetres of mercury (mmHg). 100 Pa 1 mbar ~
0.75mmHg.
Frost point (or frost-point temperature) – The
temperature at which frost forms on cooling a gas. This
is, in effect, the temperature at which air is saturated
in equilibrium with ice. It is the exact counterpart to
dew point (though values differ). Expressed in degrees
Celsius, °C, or occasionally in other units of temperature,
i.e. in degrees Fahrenheit (°F), in USA. (See also dew
point.)
Parts per million – Abbreviated as ‘ppm’, it must always
be stated whether this is by mass (weight) or by volume,
and whether the figure is the ratio of water vapour to dry
gas, or to total (moist) gas.
Parts per million by volume (ppmV, ppm(v)) –
Volume of water vapour per total volume of gas, for
an ideal gas. Sometimes expressed relative to the total
volume of moist gas (mole fraction times one million)
or sometimes relative to the total dry gas. For small
numbers of parts per million, the two are almost identical;
at higher humidity they become significantly different.
Humidity ratio – Mixing ratio.
Latent Heat – Heat stored in a substance but not
directly related to its temperature. For example, heat is
stored in a gas because this heat was originally supplied
to evaporate it. ‘Latent’ means ‘hidden’. Expressed
in energy per unit mass of substance, i.e. joules per
kilogram (7 kg-1). (See also enthalpy, sensible heat.)
Parts per million by weight, or mass (ppmW,
ppm(w)) – Sometimes used to express the amount
(mass) of water vapour relative to the total dry gas
(mixing ratio times one million), but sometimes to
express the amount relative to the total moist gas
(specific humidity times one million). For small numbers
of parts per million, the two are almost identical; at
higher humidity they become significantly different.
Mixing ratio – Mass of water vapour per unit mass of
dry air with which it is associated. It is a dimensionless
ratio, but is often expressed in grams of water per
kilogram of dry gas (g kg-1) or in other units of mass.
For low levels of moisture content, this may be expressed
in parts per million by weight, i.e. mass of water vapour
per million parts mass of dry gas (ppmw or ppm(w)).
Percentage saturation – The ratio of the actual
mixing ratio to the saturation mixing ratio at the same
temperature, expressed as a percentage (%).
NOTE: In chemical engineering this quantity is normally
termed ‘absolute humidity’ – but must not be confused
with the definition of ‘absolute humidity’ given above.
Mixing ratio is also alternatively known as ‘humidity ratio’.
NOTE: Under ordinary climatic conditions the percentage
saturation is almost identical to the relative humidity.
Moisture content – A humidity term best reserved for
general descriptive or qualitative use only. Use of this
term to identify a measured quantity should be avoided,
as there is a risk of confusion because ‘moisture content’
has been used in the past to mean both mixing ratio
and specific humidity. Moisture content is also a term
particularly used to refer to the proportion of water held
in liquids or solids.
Relative humidity – The ratio of the actual vapour
pressure to the saturation vapour pressure over a plane
liquid water surface at the same temperature, expressed
as a percentage. This is commonly understood when
the term ‘X percent relative humidity’ is used. For actual
vapour pressure, e, and saturation vapour pressure, es
e
relative humidity (in %) = ––– x 100
es
Mole – Amount of substance, which contains as many
elementary entities as there are atoms in 12 grams of
carbon 12. Expressed in moles (symbol, mol).
81
(1)
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
Temperature and condensation
One common cause of error in humidity measurement is
the occurrence of unwanted condensation. Condensation
can occur at cold spots, which are below the dew point
of the gas. In sampling systems, any condensation
totally invalidates the sampling process, since it changes
Care must be taken when expressing uncertainties,
the water vapour content of the gas. To prevent
changes or fractional differences in relative humidity. For
example, the difference between 50% RH and 52% RH is condensation, sample systems should always be kept at a
2% RH. This can also be expressed as a difference of 4% temperature above the maximum dew point, by heating
of value. It is important to distinguish clearly between these them if necessary.
two kinds of statement.
Temperature and absorption or desorption of
water
Saturation vapour pressure (of water) – Maximum
Many materials contain moisture as part of their
pressure of water vapour that can exist at a given
structure; particularly organic materials, salts, and
temperature. Expressed in units of pressure e.g. in
pascals (Pa), or in non-SI units such as millibars (mbar) or anything which has small pores. The quantity of water
in these materials depends on the humidity of the
millimetres of mercury (mm Hg).
surrounding gas, and on the temperature. When the
Sensible heat (of a gas) – Energy that resides in a gas temperature changes, water migrates from the material
according to its temperature. Expressed in terms of energy to the surrounding gas or vice versa. Like condensation,
per mass of gas, e.g. in joules per kilogram (J kg-1), or
this can cause changes in the measured humidity.
equivalent units. (See also enthalpy, latent heat.)
However, unlike condensation, there is not usually a
critical temperature: whenever the temperature changes,
Specific humidity – Mass of water vapour per unit mass water moves between the material and the gas.
of humid air. May be expressed as a dimensionless ratio, or
in grams of water per kilograms of humid gas (g kg-1) or in When measuring low dew points, desorption or
kilograms per kilogram (kg kg-1)
absorption of water vapour as the temperature changes
can produce very large errors in measurement. Even in
Vapour pressure – That part of the total pressure
normal ambient conditions, absorption or desorption can
contributed by the water vapour. Expressed in units of
begin to be significant, depending on the type of material.
pressure e.g. in pascals (Pa), or in non-metric units such as
millibars (mbar) or millimetres of mercury (mm Hg).
Temperature and saturation vapour pressure of
water
Water activity (of a substance) – Water activity (a)
The saturation vapour pressure of water depends strongly
is the relative humidity, which is eventually reached in a
on temperature. Near room temperature, the air’s
closed space where a hygroscopic substance, such as a
capacity to hold water vapour doubles for every 10°C
foodstuff, has been placed. It is the same as equilibrium
increase in temperature. The steepness of this variation
relative humidity (ERH) except that it is expressed on a
gradually changes across the temperature range. At 80°C
scale of 0 to 1 (no units), instead of 0% to 100%. Water
the saturation vapour pressure doubles for every 20°C
activity is particularly used in connection with foodstuffs.
rise. At -60°C the saturation vapour pressure doubles for
(See also equilibrium relative humidity.)
only a 5°C rise in temperature.
USAGE: The phrase ‘relative humidity’ is commonly
abbreviated RH although this is not a recognized
abbreviation. Values of relative humidity are commonly
expressed in units of percent relative humidity (% RH).
2 Significance of temperature and
pressure for humidity measurement
2.1 The effects of temperature on
humidity measurement
Temperature and relative humidity
Relative humidity is highly dependent on temperature –
especially so because vapour pressure appears twice in
the formula for relative humidity,
e
relative humidity (in %) = ––– x 100
(2) es
The effect of temperature on humidity is highly significant. Failure to take this into account can sometimes lead to
errors so large that the measurement is meaningless. In
(e is the water vapour pressure, and es is the saturation
many situations, the largest single source of uncertainty
vapour pressure at the prevailing ambient temperature.)
in a humidity measurement is the effect of temperature
differences from place to place in the process, room or
chamber. The importance of considering the temperature
effects carefully cannot be overstated when relative
humidity is the parameter of interest.
© Michell Instruments 2009-2011
82
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
Table 1. Effect of a temperature change of 1 °C at various levels of temperature and relative humidity. The change in the relative
humidity levels is not symmetric.
Relative
humidity
Temperature
10°C
20°C
30°C
40°C
50°C
60°C
10% RH
±0.7% RH
±0.6% RH
±0.6% RH
±0.6% RH
±0.5% RH
±0.5% RH
50% RH
±3.5% RH
±3.2% RH
±3.0% RH
±3.0% RH
±2.6% RH
±2.3% RH
90% RH
±6.3% RH
±5.7% RH
±5.7% RH
±5.4% RH
±4.6% RH
±4.1% RH
Roughly speaking, at room temperature, a change in
dew point of 1°C corresponds to a change in relative
humidity of 6 percent of the relative humidity value. For
example at 50% RH, an uncertainty in dew point of ±1°C
corresponds to an uncertainty of ±3% RH.
In a gas mixture such as room air, the total pressure
P(total air) of the system can be expressed as the sum of
partial pressures:
A change of 1°C in the measurement of the ambient
temperature has almost exactly the same significance.
The size of the effect under different conditions is
illustrated in Table 1.
It therefore follows that if any of the partial pressures
of the component gases varies, the total pressure
p(total) will vary. Also, if the total system pressure is
changed, either by compression or expansion, each of the
component partial pressures will BE changed by a similar
factor to p(total).
p(total) = p(nitrogen) + p(oxygen) + p(water) + p(others)
Overall, a useful rule of thumb is that ±1°C uncertainty in
either dew point or temperature leads to an uncertainty
of ±6 percent of the relative humidity value.
(3)
This basic rule can be applied to any measure of humidity
to predict the effect of changes in either component
or overall pressures. Below are some simple examples
showing the effect of pressure change.
A note on temperature measurement in air
A thermometer indicates its own temperature. It is
important to note this because a thermometer may not
always be at the same temperature as its surroundings.
Thermometers can be influenced by the temperatures of
other objects nearby (not the ones which are intended
to be measured). Thermometers can also suffer from
time lags, and self-heating errors may affect electrical
resistance thermometers. All these effects are at their
worst when a measurement is undertaken in air, as
opposed to in liquid. Errors from these sources can easily
amount to several tenths of a degree, so the effects on
relative humidity can be significant, as shown above.
Effect of doubling pressure on a relative humidity
of 40% RH at constant temperature, without
changing composition
Relative humidity is expressed as a ratio of vapour
pressures (the actual vapour pressure relative to the
saturation vapour pressure). Doubling p(total) will yield
a similar doubling of p(water). If the saturation vapour
pressure remains unchanged (i.e. if temperature is
unchanged) then a relative humidity of 40% RH would be
doubled to 80% RH.
2.2 The effects of pressure on humidity
measurement
Since all measurements of humidity stem from the
measurement of a vapour pressure of water, it follows
that variations in overall pressure of the gas system may
have an effect an the measured humidity. Throughout this
document, the values of pressure are given in absolute
terms (atmospheric pressure being 101325 Pa, or 1013
mbar), and not in ‘gauge’ pressures (where atmospheric
pressure would have a value of zero).
83
As a general approximate rule, the actual relative
humidity value can be multiplied by the fractional change
in total system pressure to give the resultant value of
relative humidity. NOTE: Where the result exceeds 100%
RH, condensation WILL occur.
This rule is similar for other measures of concentration in
terms of mass per unit volume, such as absolute humidity
(g m-3).
Effect of doubling system pressure on mixing ratio,
without changing composition
The mixing ratio of water in a gas system is simply the
ratio of the mass of the water vapour to the mass of the
dry gas.
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
If any gas is compressed or expanded without adding or
removing components, then the mass of all components
is unchanged. Therefore the mixing ratio is unaltered by
the pressure change. This can also be deduced from the
fact that the definition of mixing ratio does not involve
pressure or temperature.
The rule is similar for other dimensionless measures of
concentration (those expressed in mass per unit mass,
or volume per unit volume), such as mole fraction
and specific humidity, including cases where these are
expressed in terms of parts per million.
Effect of doubling system pressure on dew-point
temperature, without changing composition
The dew-point temperature of a System is directly
related to the water vapour pressure of that system.
From equation (2) it can be seen that a doubling of
total pressure p(total) will yield a doubling of the water
vapour pressure, p(water). Reference to vapour pressure
tables will allow the new dew-point temperature to be
calculated.
For example, for a system of pure water vapour with a
dew point of +10°C, the water vapour pressure is about
1228 Pa. If the system pressure is doubled, the resultant
water vapour pressure will be 2 x 1228 = 2456 Pa, which
equates to a dew-point temperature of about +20.8°C.
For dew points in the presence of air or other gases
(rather than pure water vapour alone), a correction may
need to be made for the water vapour enhancement
factor (see below).
Water vapour enhancement factor
The examples above assume that all the component
gases exhibit ‘ideal gas’ behaviour. In practice a small,
pressure-dependent correction may be required: the
‘water vapour enhancement factor’.
In air, this numerical correction is less than 1% of value
when pressure is doubled from atmospheric pressure. For
a tenfold increase from atmospheric pressure, the effect
is between about 1% and 10% of value, depending on
the dew point of the gas.
3
Selection of a type of hygrometer
3.1 Identifying measurement needs
To ensure ‘fitness for purpose’ it must be clear first of all
what is the purpose. Is a humidity measurement needed
at all? If so, what use is it to the business or process?
© Michell Instruments 2009-2011
To be useful, how should the results be expressed? Is
the measurement to meet a practical need, or to comply
with a documented specification, and is the specification
meaningful and realistic? Once the need and aim of
making the measurement is clear, it is important to decide
what factors are relevant to achieving this aim. The user
should consider the following issues:
3.2 Measurements required
Relative or absolute – Which unit or scale of
measurement? The quantity of interest may be relative
humidity, dew point, or some other measure of the
concentration of water vapour.
It is best to select a method of measurement which
intrinsically detects the quantity of interest. Many
hygrometers display results in terms of two or more
humidity parameters. This is often useful, but it should
be understood that normally only one parameter is
being measured, and the other values are the result of
numerical conversions. Because of this, an instrument
might give a reliable indication of only one of the
parameters shown, while providing a less good indication
of the other parameters.
Range (humidity and other variables) – Different
types of measurement are suited to different ranges of
humidity. It is best to avoid using an instrument at the
upper or lower extreme of its range of measurement.
Ranges of temperature, flow rate, and pressure or
vacuum also need to be specified in order to select the
best instrument.
For example, where use at elevated pressure is planned,
the construction of the instrument may be as important
as the operating principle. On the other hand, for some
types of measurement, a correction may have to be
applied to the results if the pressure varies.
Performance – It is worth deciding if any particular
performance characteristics are important for the
application in question. There may be a need to set
criteria for sensitivity, stability (in terms of repeatability
or reproducibility), uncertainty, response time, resolution,
linearity or hysteresis.
Output, readout – The humidity result may simply be
shown as a number on a digital display, or on a numbered
scale. It may be given as an electrical voltage or current
signal (analog output). Several parameters or units of
humidity may be shown, together with temperature.
Readings may be given continuously or at intervals.
84
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
3.3 Instrument format and usage
End use – Humidity itself may be of interest, or humidity
may be used as an indication of the moisture content
of other solid or liquid substances. If so, it may give no
more than a very indirect indication of the actual content,
though ERH and water activity are proper indications, in a
different way, of the condition or equilibrium of materials
with the environment.
Sampling – Sampling is an important issue in all
humidity measurement. The sampling approach may be
that of ‘immersion’, where the instrument sits wholly or
partly in the environment to be measured; or the gas may
be ‘sampled’ by extracting it to the instrument through
a tube. Some immersion sensors benefit from being in
still air, some from being in moving air, and for some
the flow rate of air is critical. When measuring gases
with very low water content, the quality of the sampling
pathway is critical; hygroscopic materials in the pathway
can change the water content of the sample. Also, care
must be taken with certain types of hygrometer, which
may themselves affect the environment, by giving off
either water or heat. (Indeed any instrument introduced
at the wrong temperature will influence its environment,
affecting the measurement result.) Conversely, moisture
and heat from the operator may affect measurements
using hand-held hygrometers.
Calibration – Method of calibration, and ease of doing
so, should be considered. even when there does not
appear to be a call for highly accurate results.
Robustness – Both hygrometer sensors and casings
vary in their robustness against condensation, drying
out, temperature extremes, dust, chemical or other
contamination, vibration, or even simple handling.
Versatility – If more than one kind of use is envisaged,
the adaptability of the hygrometer should be borne in
mind.
Interchangeability – It may be desirable to have a set
of hygrometers which can be used interchangeably, or to
substitute other probes for use with the main body of the
hygrometer. It may be necessary to replace components
of the sensor which might fail. In any of these cases,
it is important to consider how interchangeable the
instruments or components really are. Interchangeability
is best ensured by calibration against a consistent
reference. However, replacing a key component of an
instrument may invalidate its previous calibration.
Type of gas – In gases other than air, chemical
compatibility may be an issue. Calibration specific to the
gas in question may be required.
Materials of construction – Aside from considering
the hygroscopic nature of materials, other aspects of
suitability may need to be addressed. Some materials
may be chemically incompatible with the environment
of interest. Materials may be unacceptable for other
reasons, such as avoidance of Molded polymers and glass
for reasons of hygiene or safety.
Maintenance – Some types of hygrometers need routine
cleaning, regeneration, or replacement of parts.
Ease of use – Some hygrometers are straightforward to
use. Others require some skill.
Availability of spares – It may be worth knowing about
spare parts; whether they can be fitted by the user, and
whether they are freely available locally and quickly. Any
consumable supplies, such as charts, should be available
and clearly coded or identified, as they are not always
interchangeable.
Use for control or monitoring – In some gases the
user simply needs to measure humidity. In others, the
humidity measurement is fed into a process of control
of humidity. If so, then access to the electrical output
in some form is usually necessary. For use in control of
humidity, the response time and the degree of hysteresis
are usually important.
After-sales service – The availability of a warranty,
or of a good maintenance or service contract may be a
factor in the decision.
Hazardous areas – In areas where there is some
hazard, such as an explosive atmosphere, suitable
precautions must be taken. For example, extraction of
sample gas to remote probes may reduce the risk in
some cases, while other sensors can be designed to be
intrinsically safe, by limiting the electrical power to a level
low enough that it cannot ignite the atmosphere. Where
this is a concern, an appropriate certification of intrinsic
safety should be sought.
4
How to interpret the data sheet
information?
Detailed below are technical terms used to make
statements about instrument performance, as typically
found in manufacturers’ data sheets. They are:
85
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
•
•
•
•
•
•
•
•
•
•
range
resolution
uncertainty (accuracy)
repeatability
reproducibility
non-linearity
hysteresis
response time
long-term stability
temperature coefficient
This list is not exhaustive, although it indicates the most
important specifications to consider when selecting an
instrument. Practical considerations such as dimensions,
power supplies and output signals, may have little
or no significance to the measurement performance
characteristics of the unit. However, these practical
elements should be carefully selected if the instrument is
to meet the full working requirement of the application.
Each characteristic is explained separately below.
However, although separately defined, it is not always
possible in practice to distinguish between some of them.
Formal definitions of these terms are given in the ISO
document ‘International Vocabulary of Basic and General
Terms in Metrology’ (Second edition, 1993).
Measuring range
The stated measuring ranges for temperature and
humidity provide guidance as to the upper and lower
temperature and humidity environments to which the
instruments sensors can be applied. Often an additional
specification: operating range (electronics) is also stated;
this confirms the conditions in which the instrument’s
electronics (other than the sensor, or probe) can safely
operate. Where a maximum or minimum humidity is
stated, it is often the case that the humidity sensor will
be damaged if these limits are exceeded.
Resolution
Where an instrument features a display of its measured
values, the indication will have a resolution of, say, 0.1%
RH or 1% RH. Specification of this in the data sheet
simply informs the user to what degree of precision
the measurement can be noted. Resolution may not
significantly affect the uncertainty of measurement,
except in the case of a coarse resolution of, say, 1% RH,
where the display will round the actual value up or down
to the nearest significant figure, thereby introducing an
additional error of up to ±1% RH, depending on the
method of rounding.
© Michell Instruments 2009-2011
Uncertainty (accuracy)
The uncertainty of a measurement is defined as the
parameter characterising the range in which the ‘true
value’ can be expected to lie. It defines a ‘margin of
doubt’ about a reading or estimated value, together with
a level of confidence (normally 95%) that the ‘true value’
will lie within this range.
NOTE: Often, the uncertainty for an instrument is
specified for ideal operating conditions at a temperature
of 20°C or 23°C. However, further contributions such
as hysteresis, linearity, reproducibility and temperature
dependence will need to be taken into account when
estimating the overall uncertainty for an instrument. The
method of use may make an important contribution to
the overall uncertainty achieved.
Strictly speaking, ‘accuracy’ is a qualitative term only.
For example, an instrument or measurement might be
described generally as ‘accurate’ or ‘not accurate’. If
accuracy is to be quantified, it should be expressed in
terms of uncertainty, for example, ‘... an uncertainty
of ±5% RH ...’ (not ‘... an accuracy of ±5% RH ...’).
However, the word ‘accuracy’ continues to be used loosely
in specifications to refer to the maximum difference
that can be expected between the reading given by an
instrument and the ‘true value’ being measured.
Repeatability
In general terms, the repeatability of an instrument is
the closeness of agreement of multiple readings repeated
under the same conditions of measurement. To quantify
repeatability, the spread or dispersion of results may be
quoted, e.g. in terms of a standard deviation of a number
of readings.
Reproducibility
In general terms, reproducibility is an instrument’s
capacity to reproduce a previous measurement. This may
be at a later date, or after undergoing significant changes
in conditions, for example, after a change of operator,
or of location. To quantify reproducibility, the spread or
dispersion of results may be quoted, e.g. in terms of a
standard deviation of a number of readings.
Non-linearity
In an ideal world, if a calibration were carried out at
two points in a measurement range (high and low) the
instrument would behave similarly at values in-between.
However, it is usual to find some deviation from this
ideal, due to non-linearity of the sensor. In other words
most sensors exhibit a calibration curve, as opposed to a
straight line.
86
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
Long-term stability
The measurement characteristics of any instrument will
change with respect to time, due to gradual changes
in electrical or material components. Estimates of longterm stability or drift, refer to the likely change in the
instrument’s measurement performance with respect
to time. Regular checks of calibration should be made
to quantify this potential problem. Although it may
sometimes be desirable to adjust the hygrometer reading
in the light of drift, performance could be compromised
by the adjustment process, and the overall drift
characteristics could be masked by frequent adjustments.
The deviation from the ideal calibration line will have a
maximum or minimum, usually expressed in the form:
‘Non-linearity ±0.5% RH’, at a given temperature. It
should also be noted that linearity characteristics can be
significantly affected by temperature. When having an
instrument calibrated, linearity is a factor to bear in mind
when deciding how many measurements are needed and
at what intervals throughout the range of measurement.
Hysteresis
Hysteresis, in general terms, is the dependence of a
reading upon whether the condition is approached from
above or below the value of interest. For example, given
a humidity cycle of say 10% RH to 50% RH to 90% RH
and back to 50% RH, most hygrometers would not give
an identical reading on both occasions at 50% RH.
Quantitatively, drift may be expressed in terms of a
time span and a figure. However, if an instrument was
subject to drift of less than 4% RH per year, it would
not follow from this that the drift over six months would
be less than 2% RH (though it could be expected to be
somewhat less than the annual figure). Drift is not always
consistent, and measurements of drift always include
some contribution from short-term variability.
Hysteresis is related to repeatability, but includes any
‘directional’ effect.
Hysteresis should be considered if the measurement is to
be used for control purposes, for example to activate onoff control of air conditioning.
Temperature coefficient
Temperature variation has a most significant influence
on relative humidity itself. In addition, every humidity
sensor has a temperature coefficient, which can be simply
explained as a change in measurement characteristic at a
different temperature. A temperature coefficient might be
expressed, for example, as 0.1% RH per °C, which could
result in an additional 5% error when measuring at a
temperature 50°C away from the calibrated temperature.
Response time
Response times are included in specifications to provide
an indication of how long the instrument takes to react to
changes in the applied condition. While the sensor itself
may have a particular response time, any screening of the
sensing element, e.g. by a protective filter, will slow down
this response. Effective air movement will speed it up.
(Constant and specified air flow is required for a response
time test.) Response times are practically always slower
for falling humidity than for rising humidity.
5
What is calibration?
Calibration is the process of comparing a measuring
instrument against an authoritative reference for the
same type of measurement, to identify any bias or
systematic error in the readings. The outcome of a
calibration is normally a certificate listing any corrections
that need to be applied to the values indicated by the
instrument, together with an estimate of the uncertainty
in the calibration, and other relevant information. For
example, a calibration of a given instrument at, say, 50%
RH, might show it to read too high by 1% RH. If so, a
required correction of –1% RH would be shown on the
certificate.
Quantitatively, response times are usually quoted in terms
of the time taken to register 63% of a step change in
the applied condition (although other conventions are
sometimes used, e.g. 90%).
Response times are usually quoted for the hygrometer
alone, at constant temperature. However, response times
of the associated sampling systems may be much greater.
Optimistic specifications of response time may raise false
expectations for the user to see stable measurements
after very short time periods. However, for most
relative humidity measurements, the time taken for the
sensor and nearby materials to equilibrate with respect
to temperature is by far the most significant factor
influencing the response time. For measurements of dry
gases, equilibration of moisture in the sampling system is
usually the key influence.
Calibration is often taken to mean ‘adjustment of the
instrument to read correctly’. This is not true. Calibration
and adjustment of an instrument are quite separate
concepts, and the two should not be confused. Thus,
when arranging for the calibration of any instrument,
it is important to establish clearly whether or not the
instrument is to be adjusted as well as calibrated. If so,
it should be specified whether calibration information is
required only after adjustment, or whether results are
also required for the initial or ‘as found’ condition.
87
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
Any calibration corrections identified on a certificate of
calibration should be applied to measured values obtained
using that instrument. If the calibration corrections
cannot be applied, the quoted uncertainty in the results
should include an allowance for this.
What is checking?
A measurement check is not the same thing as a
calibration. A check is a test to confirm whether or not
some condition is fulfilled (for example to confirm that
the performance of an instrument has not drifted).
The outcome of a check is not normally a certificate of
calibration. However, checks of a measuring instrument
against another (stable) instrument are often useful at
intervals in between calibrations.
6
Recommended practices in humidity
measurements
6.1 General practical recommendations
• Where relative humidity is of interest, a direct measurement
of relative humidity is usually best. Where an absolute
measure of humidity is needed, choose dew point,
vapour pressure or similar measurements.
• Establish the measurement requirements at the
purchasing stage in order to have the right instrument
for the job.
• Allow hygrometers to equilibrate in any new
environment. This is particularly necessary after
changes in temperature due to transportation or
storage. Depending on the instrument and on how
great the change in conditions, this may require from
only a few minutes to many hours.
• Follow Michell Instruments’ care instructions for
the instrument. Some instruments need routine
cleaning or other maintenance. Before using any
solvent cleaner, check with Michell Instruments that
this will not harm the sensor or other materials of
construction.
• Wherever possible, ensure that hygrometers are
calibrated under the conditions of use, i.e. at similar
values of humidity and temperature, and (if relevant)
in similar conditions of pressure, airflow, etc.
• Keep a record of calibrations and any adjustments to
the hygrometer. This will show the long-term stability
of the instrument and allow the associated uncertainty
to be assessed.
© Michell Instruments 2009-2011
• Check instruments, if possible, at intervals between
calibrations, by comparison with another (stable)
instrument, to monitor for long-term drift. Routine
checks are also useful before and after subjecting an
instrument to transportation or other stress, which
might lead to a shift in its performance. Where the
check is against two (or more) instruments this is even
better: not only does this add confidence, but in the
event of one instrument drifting among a set of three,
it can be seen which reading is most suspect.
• Cleanliness of the environment will affect different
hygrometers in different ways. Dust and airborne
droplets should be avoided or filtered out if possible.
Contaminants can come from the most surprising
sources, ordinary urban pollution, for example.
• The readings given by some types of hygrometer
are sensitive to gas type. For any Instrument which
reads in terms of mass per unit volume, e.g. in grams
per cubic metre, it must be confirmed whether the
calibration is valid for the gas in use.
• Avoid using instruments in direct sunlight or near any
other source of heat, unless they are suitably shielded
to prevent measurement errors.
6.2 Sampling in general
• Relative humidity measurements should be carried
out at a representative temperature. Failure to allow
temperature equilibration will lead to a false indication
of the relative humidity.
• Variations in vapour pressure from place to place can
occur where an environment is subject to any addition
or removal of water. If so, care must be taken over
where to make a measurement in order to obtain a
representative result.
• Sources and sinks of water vapour should be avoided
in any sampling system. Invasion of stray water
can be minimised by attention to leaks, hygroscopic
materials, droplets and condensation. The lower the
humidity, the more critical these precautions are.
• Hygroscopic materials should be avoided. Many
materials contain moisture as part of their structure,
particularly organic materials (whether natural or
synthetic), salts (or anything which contains them),
and anything which has small pores. Temperature
changes can increase the tendency of these materials
to affect the humidity of the surrounding air.
88
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
• For measurements in the region below 0°C it must be
clear whether the condensate is dew or frost. Failure
to distinguish between these can result in errors of
about 1°C for every 10 °C below zero.
• Condensation in a sampling process can invalidate
humidity measurements by reducing the water content
of the gas being measured. What is more, condensed
liquid may alter the humidity elsewhere by dripping
or running to other locations and evaporating there.
In these circumstances, measurement results may be
misleading if hygrometer location is not considered
carefully.
6.4 Relative humidity in general
• Due care must be taken of temperature.
• Water droplets or mist must be avoided. These can
result in overestimates of the humidity of the air
between the droplets. Such results may exceed 100%
RH, or may be impossible to interpret meaningfully.
Droplets of liquid also damage some electrical types of
humidity sensor. Filtering the air sample can eliminate
droplets.
• Care must be taken when expressing uncertainties,
changes or fractional differences in relative humidity.
For example, the difference between 50% RH and
52% RH is 2% RH. This can also be expressed as a
difference of 4% of value. It is important to distinguish
clearly between these two kinds of statement.
• If pumps are used for sampling gas, these should be
located after the hygrometer, to avoid contaminating
the measurement environment. Where possible,
oil free pumps should be used, or filters employed.
Oscillations in pressure due to pumping can
sometimes be reduced or buffered using a needle
valve or a reservoir of large volume.
6.5 Recommendations specific to
ranges of measurements
• Special treatments such as filtration can change the
amount of moisture in a gas. Some drying agents take
out other gases, too.
• High humidity, above the ambient range - Ample lines
should be maintained above the dew point of the gas
being measured, to avoid condensation. Electrical
trace heating is often the most practical method.
• Ambient humidity - Avoid using hygrometers near the
body, which is a source of heat and moisture. Do not
breathe close to the measurement.
• When sealing any sensor or probe into a port or
manifold in a duct or chamber, leaks through the
probe or electrical cable should be considered. These
are not always sealed against passage of ambient air.
• Low humidity, and very dry gases - If possible,
prepare for measurements by flushing sample lines
and hygrometers with dry gas, or by evacuating to
low pressure. Drive off stray residual water by baking
assemblies if possible (but not instruments – unless
designed for this!). The lower the moisture content
to be measured, the more dramatically the required
drying time multiplies.
• Where sampling involves a step change in
temperature, pressure or gas flow rate, relative to
the process being sampled, results may need to be
converted or interpreted. For example ‘pressure dew
point’ will differ from the value found after expanding
the gas sample to atmospheric pressure. Care should
be taken to distinguish between ‘gauge’ and absolute
values of pressure.
• Avoid hygroscopic materials. At low humidity (anything
much below a dew point of 0°C) the amounts of
water given off by organic and porous materials can
dramatically affect the value of humidity. The lower
the level of moisture, the more significant the effects.
6.3 Dew point in general
• Choose impermeable materials, to avoid inward
diffusion of moisture through sampling tubes and
enclosures. Steel and other metals are practically
impermeable. PTFE (‘Teflon’) is only slightly permeable
and will usually be satisfactory for dew points above
-20°C, and sometimes below this level. Materials
such as PVC and rubber are relatively permeable and
so totally unsuitable at low humidity, and not really
satisfactory in any humidity range.
• The measuring environment and all parts of the
sampling pathway must be kept above the dew point if
condensation is to be avoided. Electrical trace heating
or other heating methods should be used if necessary.
An excess temperature of 10°C above the dew point is
usually a safe margin.
89
www.michell.com
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specification changes without notice. Please contact us for latest version.
Humidity and Dew-Point Instruments
A Guide to the Measurement of Humidity
• Surface finish of pipework is important for very dry
gases. Even the tiny quantities of water adsorbed on
the surfaces of non-hygroscopic materials can have
significant effect. Polished or electropolished steel is
recommended for the best results.
• Clean environments are always best for humidity
measurements, but this is especially critical at very low
humidity. Even fingerprints harbour water. High purity
cleaning agents are recommended: Analytical Reagent
(AR) quality solvents for oil-based contaminants,
and purified water (distilled or deionized) for salts.
Cleaning should be followed by thorough drying by a
clean method.
• Sample tubing should be as short in length as
possible. The surface area should be minimised by
using the narrowest tubing that the flow conditions
will permit.
• Protective filters can slow the response time of
sensors. This can be avoided by removing any filter,
but the benefit must be weighed against the risk of
damage to the sensor.
• Sensors should not normally be submerged in liquids.
In the case of a resistive (electrolytic) sensor, water
or other liquids would certainly damage the sensor
beyond repair.
• Salt solutions are especially commonly used for
calibration of electrical sensors, and should be
provided with traceability directly or via a calibrated
hygrometer. Protection of sensors from direct
contact with salt or solution is most important as
contamination would destroy or seriously impair the
sensing element.
Impedance dew-point hygrometer
• Adequate flow of the gas sample should be ensured,
to minimise the influence of sources of stray water in
the flow path.
• Sensors constructed using aluminium oxide or
ceramics essentially respond to vapour pressure. They
are often used at high pressure, or to sample gas
originating from systems at high pressure. If so, care
must be taken to ensure that the sample pressure is
known, and a correction applied if necessary.
• ‘Dead ends’ should be avoided, as they cannot easily
be flushed.
• As for other electrical sensors, filtration should be
used to protect from dust and droplets or mist.
• Back-diffusion of moisture should be minimised, e.g.
by fast flow rates of gas, long exhaust tubes after the
sensor, or by valves which isolate the low-humidity
region from ambient air.
• Regular calibration is particularly important for
ceramic hygrometers. The calibration intervals may be
dependent on usage.
• Avoid leaks. Minimising the number of connections
(elbows, tees, valves, etc.) helps with this.
6.6 Practical recommendations for
specific types of hygrometer
Relative humidity capacitive sensor
• Care should be taken to avoid mechanical shock
(impact) or thermal shock (sudden temperature
changes). Sensors should be protected from steam or
water sprays, and from direct sunlight.
• Where a sensor is at risk of exposure to dust,
droplets, or the occasional knock during handling, the
appropriate guard or filters for the sensor head should
be used.
• Aluminium oxide sensors normally exhibit a
temperature coefficient, which may be partially
compensated within the instrument, but not totally. If
the hygrometer must be used at a temperature, other
than that at which it was calibrated, ensure that any
necessary correction to the reading is made, and that
any resulting uncertainty is taken into account.
• When using the sensors at low levels of moisture, the
precautions listed above under ‘sampling’ and ‘low
humidity’ should be observed.
• Any temptation to breathe on the sensor, or to wave
it over cups of tea, etc. should be resisted. Filters and
saturation guarding may protect the sensor, but these
actions carry a risk of damage by condensation or
other contamination.
© Michell Instruments 2009-2011
90
Humidity and Dew-Point Instruments
Notes
91
www.michell.com
Humidity and Dew-Point Instruments
Notes
© Michell Instruments 2009-2011
92
Asia
Michell Asia
PO Box 3149
Joondalup
WA 6027
Australia
France
Michell Instruments SAS
2-4, rue Jean Desparmet
69008 Lyon, France
T: [33] 437 53 88 20
F: [33] 437 53 88 21
E: fr.info@michell.com
T: [61] 893 046587
E: au.info@michell.com
Germany/Austria/Switzerland
Michell Instruments GmbH
Industriestrasse 27
D-61381 Friedrichsdorf, Germany
Benelux
Michell Instruments Benelux BV
Krombraak 11
4906 CR Oosterhout
The Netherlands
T: [49] 6172 591700
F: [49] 6172 591799
E: de.info@michell.com
T: [31] 162 680 471
F: [31] 162 437 566
E: nl.info@michell.com
China
Michell Instruments (Shanghai) Ltd
Room 505, Qilai Building
889 Yishan Road
Shanghai, 200233
P R China
T: [86] 21 5401 2255
F: [86] 21 5401 2085
E: cn.info@michell.com
Middle East
Michell Instruments Middle East
P-06, #097
Sharjah Airport Int’l free zone
Sharjah,
United Arab Emirates
T: [971] 6 5575028
F: [971] 6 5575029
E: me.info@michell.com
UK
Michell Instruments Ltd.
48 Lancaster Way Business Park
Ely, Cambridgeshire, CB6 3NW
UK
T: [44] 1353 658000
F: [44] 1353 658199
E: info@michell.com
Italy
Michell Italia Srl
Via Capecelatro, 10
20148 Milano
Italy
T: [39] 02 4047194
F: [39] 02 40010565
E: it.info@michell.com
Japan
Michell Japan KK
Musashino Center Building
1-19-18 Nakacho, Musashino
Tokyo 180-0006
Japan
USA
Michell Instruments Inc
319 Newburyport Turnpike, Suite 207
Rowley, MA 01969
USA
T: [1] 978 484 0005
F: [1] 978 843 7669
E: us.info@michell.com
T: [81] 422 502600
F: [81] 422 521700
E: info@michell-japan.co.jp
Michell Offices
Michell Representatives
www.michell.com
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising