Model 755A - Southeastern Automation

Product Data Sheet
PDS 103-755A.A01
January, 2003
Model 755A
Gaseous Oxygen Analyzer
• Canadian Standards Association-certified
• High resolution LED digital display
• Ideal for oxygen purity measurement
• Small, rugged, shock-resistant sensing
unit
• Plug-in alarms/current output options
• Adjustable speed of response
• Barometric pressure compensation
The Model 755A gaseous oxygen analyzer from
Rosemount Analytical provides continuous measurement
of gaseous oxygen with the highest accuracy and
reliability. The heart of this instrument is a compact
paramagnetic sensing unit, designed to monitor a wide
variety of ranges for virtually every application.
FEATURES
The Model 755A gaseous oxygen analyzer uses the
physical paramagnetic measurement technique
exclusively. This method offers distinct operating
advantages over combination measurements, such as
thermal conductivity, thermal convection or chemical
reaction. Two advantages of this technique are:
(1) faster response and, (2) linear detector output.
The 755A continuously measures from 0 to 1% to 0 to
100% oxygen with a resolution of 0.1% fullscale.
Standard zero or suppressed zero is available with a
range span as narrow as 1% and a zero suppression as
large as 99%. Standard response time is 20 seconds.
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On-line ordering available.
In addition, the Model 755A includes an integral absolute
pressure compensation circuit. This provides the user
with an oxygen readout that is automatically corrected for
barometric pressure variations. (See General
Specifications.)
Housed in a NEMA-3R aluminum case, the analyzer is
available with options for dual alarms and 0 to 20 mA or
4 to 20 mA current output. All optional features can be
added at the factory or in the field with the simple addition
of plug-in circuit boards. The paramagnetic sensing
assembly is mounted on a platinum suspension for shock
resistance. This assembly is designed for ease of
maintenance and installation.
PRINCIPLE OF OPERATION
The Model 755A measures the paramagnetic
susceptibility of oxygen. This susceptibility is much
higher than other common gases. When oxygen is
present in a magnetic field, the oxygen tends to
concentrate in the area of the magnetic field.
The Model 755A measures the total magnetic
susceptibility of the sample. This total is almost entirely
due to the oxygen present, so the measurement is an
accurate indication of oxygen content.
The test body is mounted on a platinum suspension in a
non-uniform magnetic field (see Figure 1). The magnetic
force exerted upon the test body is proportional to the
difference in the volume magnetic susceptibilities of the
test body and the surrounding gas. If the gas is more
paramagnetic than the test body, the magnetic force
tends to repel the test body; and if the gas is less paramagnetic, the magnetic force tends to attract the test
body into the magnetic field.
A diamond-shaped mirror is mounted on the platinum
suspension and reflects light from the prefocused light
source equally onto two photocells when the test body
is in the neutral position.
When the volume magnetic susceptibility of the gas
increases, a magnetic force is applied to the test body
rotating it out of the field. The suspension mirror on the
test body also rotates so that the photocells become
unequally illuminated and, through the amplifier, apply
feedback current to the test body. The electromagnetic
force generated by the feedback current is opposite and
almost equal to the magnetic force.
As a linear function of the oxygen concentration, this
feedback current is easily converted to an analog output
signal which is used for readout and recording purposes.
Barometric pressure has a pronounced effect on the
calibration and operation of oxygen analyzers. These
effects are much more pronounced on higher
concentrations, especially when using suppressed ranges
such as 99 to 100% oxygen. In the Model 755A, the
analyzer exhaust port is usually vented directly into the
atmosphere. Internal circuitry automatically corrects the
oxygen readout for barometric pressure variations.
PHYSICAL SPECIFICATIONS
Case Mounting: Panel mounting (surface or stanchion
accessory)
Case Classification: General purpose enclosure
(CSA-certified) meets NEMA-3R
Air Purge (Optional): Type Z per ANSI/NFPA 496*
ALARM SPECIFICATIONS
Contacts: 2 independently adjustable relay contacts,
SPDT relay
Adjustable: 1 to 100% fullscale
Contact Ratings: 5 A, 240 VAC resistive
5 A, 120 VAC, 28 VDC, resistive
Dead Band: Adjustable from 1 to 20% of fullscale
* When installed with user supplied components, meets requirements for Class I, Division 2 locations per National Electrical Code (ANSI/NFPA 70) for analyzers
sampling non-flammable gases. Analyzers sampling flammable gases must utilize an explosion-proof enclosure or be protected by a continuous dilution purge
system in accordance with standard ANSI/NFPA 496-1989, Chapter 8. Consult factory for recommendations.
OUTLINE AND MOUNTING DIMENSIONS
A. Inlet for optional purge (1/4-18 NPT)
B. 1-1/16 (27 mm) DIA or 3/4 conduit fitting
recommended for alarm connections
C. 1-1/16 (27 mm) DIA for 3/4 conduit fitting
recommended for signal output connections
D. 1-1/16 (27 mm) DIA for 3/4 conduit fitting
recommended for power cable
E. Outlet for optional purge (1/4-18 NPT)
F. Bracket and hardware for panel mounting
supplied (quantity two)
G. Wall mounting brackets 3/16 (5 mm) thick
x 12-1/2 (318 mm) long and hardware
(optional accessory kit)
H. Vertical or horizontal stanchion, mounting
bracket and hardware for 2" (51 mm) pipe
(optional accessory kit)
1. Recommended panel cutout, 10-9/16 (268 mm)
wide x 12-5/8 (321 mm) high (1" [25.4 mm] max.
panel thickness)
2. All dimensions are in Inches ±1/16 (2mm)
Page 2
GENERAL SPECIFICATIONS
Digital Display: 0.00 to 100.00% oxygen
Output to Recorder: Any incremental span, selectable:
0 to 1, 0 to 2, 0 to 5, 0 to 10, 0 to 20, 0 to 50, or 0 to 100%
oxygen within the overall range. Other spans available as
special order
Reproducibility: ±0.01% oxygen
Response Time: (90% of fullscale) Adjustable from 5 to
25 seconds
Sample Flow Rate: Range 50 to 500 cc/min. Constant
flow at 250 cc/min. ±20 cc/min. recommended
Inlet Pressure Range: 12.7 psia to 24.7 psia
(88 kPa to 170 kPa)
Ambient Temperature Limits: Maximum: 120°F (49°C)
Minimum: -20°F (-29°C)
Sample Dryness: Sample dewpoint below 110°F (43°C),
sample free of entrained liquids
Sample Temperature Requirements: 50° to 150°F
(10° to 66°C)
Barometric Pressure Compensation: Oxygen readout
automatically corrected to within ±1% of fullscale for
barometric pressure variations within 3% of target value
and to within ±2% of fullscale for barometric pressure
variations within ±5% of target value. The target value
may be set anywhere within range of 12 to 15 psia (83 to
103 kPa). Outlet vented to atmosphere
Zero and Span Drift: ±1% fullscale (±2% of fullscale for
99 to 100% range) per 24 hours provided that ambient
temperature does not change by more than 20°F (11°C).
±2.5% fullscale per 24 hours with ambient temperature
change over entire range
NOTE: 99 to 100% range specifications apply over
temperature span of 40° to 100°F (4° to 38°C)
Materials in Contact with Sample Gas: Stainless steel,
glass, titanium, Paliney No. 7**, epoxy resin, Viton-A***,
platinum, nickel
Electrical:
Supply Voltage and Frequency:
115V ±10V, 50/60 Hz selectable when ordered
230V ±10V, 50/60 Hz
Power Consumption: 300 W maximum, 75 W nominal
Output: 0 to 10 mV, 0 to 100 mV, 0 to 1 V, 0 to 5 VDC
(Isolated Current Output Optional: 4 to 20 mA, 0 to 20
mA)
Note: Intended Use – The Model 755 Series is intended
for use as an industrial process measurement device only.
It is not intended for use in medical, diagnostic or life
support applications and no independent agency
certifications or approvals are to be implied as covering
such applications.
Specifications subject to change without notice.
** Trademark of J.M. Ney Co., Hartford, CT
*** Trademark of E.I. DuPont de Nemours & Co., Inc.
Page 3
ORDERING INFORMATION
755A
MODEL 755A OXYGEN ANALYZER – DIGITAL METER
Code
11
Ranges
0-0-100% Oxygen on Display
(Recorder Output can be selected for any full scale span of
5%, 10%, 20%, 50%, or 100% using any zero offset) 5
0.0-100% Oxygen on Display
(Recorder Output span of 5% or greater for zero based ranges)
Special
2
9
Code
1
2
3
4
09
Corrosion Resistance
Standard Detector
Detector with rhodium plated current loop 3
Detector with stainless steel tubing 4
Detector with rhodium plated current loop and stainless steel tubing
Special
Code
01
02
99
Output
Voltage: 0-10 mV, 0-100 mV, 0-1 V or 0-5 VDC
Current: 0, 4-20 mA, Isolated
Special
Code
00
01
99
Alarm Relays
None
Dual
Special
Code
01
02
03
04
99
Case
General Purpose (NEMA-3R)
General Purpose W/ISA Type Z Purge 2
General Purpose W/Tropicalization
General Purpose Purge W/Tropicalization
Special
Code
01
02
99
Operation
115V, 50/60 Hz
230V, 50/60 Hz
Special
Code
00
99
755A
11
01
00
01
01
00
Features as selected above
Special
EXAMPLE
Notes: Pricing for the options listed above applies only when they are supplied as installed options on new instruments.
1
Display recorder output of increments of less than 5% using any zero offset (add 5451).
2
Flow or pressure indicator not supplied.
3
Rhodium plated current loop used when sample stream contains chlorinated hydrocarbons/chlorine.
4
Stainless steel tubing used when sample stream contains chlorinated hydrocarbons, acids and H2S.
5
In order to deliver analyzer in a timely manner, please specify the uppermost range used in your application (i.e., 99-100%, 95-100%, etc.)
ACCESSORIES
Part No.
190365
638661
245364
(Order as separate line item)
Description
Pipe Stanchion Mounting Kit
Wall Mounting Kit
Instruction Manual
MISCELLANEOUS PRODUCT INFORMATION
Mounting Dimension Drawing
632349
Schematic
617149
Product Information Bulletin
L71-755
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to
be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are
governed by our terms and conditions, which are available on request. We reserve the right to modify or improve the designs or specifications of our products
at any time without notice.
Emerson Process Management
Rosemount Analytical Inc.
Process Analytic Division
1201 North Main Street
P. O. Box 901
Orrville, OH 44667-0901 USA
T 330.682.9010
Toll Free in US and Canada 800.433.6076
F 330.684.4434
e-mail: gas.csc@EmersonProcess.com
www.processanalytic.com
© Rosemount Analytical Inc., 2003. All rights reserved.
Printed in U.S.A. on recycled paper.