9046736 Infoflip PGD EN Cover Content fin

9046736 Infoflip PGD EN Cover Content fin
D-23492-2012
Dräger's Guide to
Portable Gas Detection
(according to EN Regulations)
ST-16039-2008
STL-1097-2008
Gases – what is Gaseous Matter?
Matter with a temperature above its boiling point is said to
be a gas. With respect to a human environment (normal
conditions), any substance with a boiling point below 20°C
at normal pressure is a gas. The lightest gas is hydrogen
(H2, fourteen times lighter than air); the heaviest gas (about
ten times heavier than air) is tungsten hexafluoride (WF6).
Under normal conditions, 1 cm3 of gas contains about 30 trillion
molecules. The average distance between each of these molecules
is only about three nanometers. They swarm through space at
some 100 to 1000 meters per second and collide some billion
times per second with other molecules, so that between two
collisions they can only fly about 50 to 100 nanometers. With
each collision, they change their flight direction and transfer
energy to their collision partner.
This is an entirely random movement of molecules, which is
macroscopically measurable such as temperature (average kinetic
energy of all molecules), pressure (average momentum of all
molecules striking a surface) or extension (volume). Pressure,
temperature and volume are in a fixed relationship based on
external conditions. Ideally, they follow the so-called ideal gas
laws, i.e. at constant pressure, a gas volume changes proportional
to its temperature – e.g. it expands when heated
– at constant pressure the gas volume changes
proportional to its temperature – e.g. the volume will be
increased when heated
– at constant volume (such as in a closed vessel) the
pressure changes proportional to the temperature –
e.g. the inner pressure of the vessel increases when heated
– at constant temperature, pressure changes inversely
proportion to volume – e.g. the internal pressure
increases when the gas is compressed
The extremely quick, random movement of gas molecules is also
the reason that gases mix easily and never segregate from each
other. The movement of molecules toward lower concentrations
(diffusion) is also based on these molecular characteristics and
plays an important role in the measuring principles of gas sensors.
In general, these diffusion processes are quicker, the faster the
molecules move (the hotter the gas) and the lower the molar
weight (the lighter the gas).
Gases – what is Gaseous Matter?
STL-1098-2008
Vapors – aren’t they Gases too?
Unlike gases – of which there may be only 200 to 300 – the
term vapor is used for the gaseous state of matter below its
boiling point. Vapor always exists in equilibrium with its liquid
(sometimes also solid) phase – it condenses and evaporates
depending on the temperature. This behavior is best recognized
in water: The cooling of humid air at nighttime causes fog
(condensation) – but the warmth of the morning sun dissolves
the fog again (evaporation).
In a closed vessel, the maximum vapor concentration always occurs
above the surface of a liquid. This concentration is dependent on
the temperature of the liquid. From a microscopic point of view,
vapor is generated by the random movement of the liquid’s
molecules and their ability to overcome the surface tension and
mix with the air molecules above.
Each liquid has a certain characteristic vapor pressure that solely
depends on the liquid’s temperature. This pressure is equal to the
atmospheric pressure when the liquid reaches its boiling point.
The graph of this correlation is known as the vapor pressure curve,
which enables the determination of the maximum possible vapor
concentration at any given temperature.
ST-1099-2008
Vapor pressure curve of liquid n-hexane
Dividing the maximum possible vapor pressure by the ambient
pressure results in the saturation concentration, which is measured
in Vol.-%. For n-hexane at 20°C (vapor pressure 162 mbar) at an
ambient pressure of 1000 mbar, the maximum possible n-hexane
concentration is 16.2 Vol.-%.
Vapors – aren’t they Gases too?
Our Atmosphere
While continuously decreasing its specific weight, our
atmosphere extends far into deep space. The sky’s blue color is
caused by scattering sunlight on air molecules (mainly nitrogen
and oxygen). The sky is actually already black at a height of
about 21 km. If the atmosphere was maintained at a constant
pressure of 1013 mbar, its height would be 8 km and the UVabsorbing stratospheric ozone layer would only be 3 mm thick.
Typical composition of the earth’s atmosphere in ppm:
Gas
Main gases
N2 – Nitrogen
O2 – Oxygen
H2O – Water vapor
Ar – Argon
CO2 – Carbon dioxide
Trace gases
Ne – Neon
He – Helium
CH4 – Methane
Kr – Krypton
H2 – Hydrogen
N2O – Nitrous oxide
CO – Carbon monoxide
Xe – Xenon
O3 – Ozone
Additional trace gases
Total
Dry
Composition
Humid
780 840
209 450
0
9 340
340
768 543
206 152
15 748
9 193
335
18
5
1.8
1.1
0.5
0.3
0.09
0.09
0.07
3.05
1000 000
18
5
1.8
1.1
0.5
0.3
0.09
0.09
0.07
3.0
1000 000
1 Vol.-% = 10 000 ppm; assumed for moist air: 68% r.h. at 20 °C
The earth’s atmosphere has a mass of about five quadrillion tons
(5.235·1018 kg), pressing down on the earth’s surface of 0.507·1015 m2.
This is why we have an atmospheric pressure of 10,325 kg/m2,
which corresponds to our standard pressure of 1,013 mbar.
Atmospheric pressure decreases as altitude increases:
Altitude
-1000 m
- 500 m
0m
500 m
1000 m
1500 m
Atmospheric
pressure
1148 mbar
1078 mbar
1013 mbar
952 mbar
900 mbar
840 mbar
Height
2000 m
3000 m
4000 m
5000 m
6000 m
8000 m
Atmospheric
pressure
795 mbar
701 mbar
616 mbar
540 mbar
472 mbar
356 mbar
Since fewer molecules are present in a given volume at a lower
atmospheric pressure, the result of partial pressure measuring
gas detectors is always dependent on the atmospheric pressure.
Our Atmosphere
Oxygen
While nitrogen, as the main gas in our atmosphere at more
than 78 Vol.-%, is completely inert and, despite its excess,
cannot be used by plants as a much needed fertilizer in this
gaseous state, oxygen is very reactive and forms the basis
of our breathing and existence, moreover: the basis of nearly
every living being.
There is nearly 21 Vol.-% oxygen in our atmosphere. Oxygen deficiency
is life-threatening and cannot be detected by our sense of smell.
As a general rule, oxygen deficiency is caused by the release of
inert gases, which then in turn displace oxygen. Since roughly
one-fifth of the atmosphere is oxygen, the oxygen concentration is
only reduced by one-fifth of the concentration of inert gas. For
example, if 10 Vol.-% of helium is released into the atmosphere,
the oxygen concentration decreases by 2 Vol.-%, while the nitrogen
concentration is reduced by 8 Vol.-%. Because liquid nitrogen
(-196 °C) is often used in industrial areas, a dangerous oxygen
deficiency can quickly arise due to the evaporation of this liquid
nitrogen.
Enhanced oxygen concentrations (e.g. more than 25 Vol.-%)
cannot be sensed by humans, but have severe consequences
with respect to the flammability of materials, and may even cause
auto-ignition. This is the why explosion protection measures are
only related to the atmospheric oxygen concentration.
When does it become dangerous?
Oxygen
concentration
in Vol.-%
Below 17
11 to 14
8 to 11
6 to 8
Below 6
Oxygen
Symptoms
partial pressure
in mbar
Below 170
Dangerous tendencies due
to oxygen deficiency
110 to 140
Unnoticeable decrease
in physical and
mental capabilities
80 to 110
Possible sudden loss
of consciousness without
warning after a certain period
of exposure
60 to 80
Loss of consciousness within
a few minutes, resuscitation
possible if performed instantly
Below 60
Immediate loss of consciousness
Oxygen
ST-11289-2008
Ex, Ox, Tox – Gas Hazards!
Gases and vapors are almost always dangerous! If gases
do not exist in their familiar and breathable atmospheric
compositions, safe breathing is already at risk. Furthermore:
All gases are potentially dangerous. Whether in liquefied,
compressed or normal state – it is their concentration that
is crucial.
There are basically three categories of risk:
– Risk of explosion (Ex) by flammable gases
– Oxygen (Ox)
Risk of asphyxiation due to oxygen displacement
Risk of increased flammability due to oxygen enrichment
– Risk of poisoning (Tox) by toxic gases
Without auxiliary tools, humans are not able to recognize these
dangers early enough to initiate appropriate countermeasures.
With few exceptions, our nose has turned out to be an extremely
unreliable warning instrument.
For example, low concentrations of hydrogen sulfide can be sensed
through the typical odor of rotten eggs, but our nose cannot detect
the lethal high concentrations. Escaping into areas assumed to
be safe due to the lack of smell has already caused many fatal
accidents.
Even harmless gases such as argon, helium or nitrogen may become
dangerous when a sudden release of these gases displaces vitally
important oxygen. Here, there is a risk of suffocation. Oxygen
concentrations of less than 6 Vol.-% are known to be lethal. Excess
oxygen increases the risk of flammability and may even cause
auto-ignition of flammable materials. If ignited, flammable gases and
vapors not only cause considerable damage to assets and property,
but they can also compromise human life.
It is essential to detect Ex, Ox, and Tox risks reliably and to
take appropriate measures to protect human lives, assets and
the environment.
Whether Dräger-Tubes or portable gas detectors – Dräger
offers you individual solutions to tackle gas risks professionally.
Ex, Ox, Tox – Gas Hazards!
Toxic Gases and Vapors
The toxicity of gases and vapors used in industrial processes is
determined using laboratory experiments that calculate the LC50
rate. Based on these investigations and additional scientific
and occupational health investigations, authorized commissions
in several countries make their recommendations for limit
values, which are then legally binding. In Germany, this is the
Federal Institue for Occupational Safety and Health (BauA).
These limit values are defined to prevent employees from being
harmed, provided they do not breathe in a higher gas concentration
than the stated threshold limit value throughout their entire working
lives. This, however, must be ensured.
Limit value*
5000
1000
500
200
100
50
ppm
ppm
ppm
ppm
ppm
ppm
20 ppm
10 ppm
5 ppm
1 ppm
500 ppb
200 ppb
100 ppb
50 ppb
10 ppb
Selected substances that
correspond to this limit value
Carbon dioxide
Propane, Butane
Acetone
Methyl ethyl ketone (MEK)
Butanol
n-Hexane, Toluene
Acetonitrile
Chlorobenzene
Diethylamine
1.1.2.2-Tetrachloroethane
Chlorine
Methyl chloroformate
Chlorine dioxide
Glutaraldehyde
Methyl isocyanate
* 10 ppb Methylisocyanate
Status 2010, according to TRGS 900 (Germany)
T+ very toxic
LC50 < 0,5 g/m3
Arsine, Boron trichloride, Boron trifluoride, Bromine, Diborane,
Fluorine, Hydrogen cyanide, Hydrogen fluoride, Hydrogen phosphide,
Hydrogen sulfide, Nitrogen dioxide, Nitrogen monoxide, Ozone,
Phosgene, Sulfur tetrafluoride, Tungsten hexafluoride
T toxic
LC50 = 0,5 ... 2,0 g/m3
Acetonitrile, Ammonia, Benzene, Carbon disulfide, Carbon monoxide,
Chlorine, Cyanogen, Hydrogen chloride, Methanol, Methyl bromide,
Nitrogen trifluoride, Sulfur dioxide
LC50 (LC stands for lethal concentration) reflects the gas concentration in air that will
kill 50% of laboratory animals (primarily white lab rats) when inhaled for a certain period
of time (typically four hours).
Toxic Gases and Vapors
Flammable Gases and Vapors
Flammable gases become more dangerous when they have a
relatively low explosion limit (LEL). Flammable vapors become
more dangerous when they have a relatively low flash point. The
flash point is defined by the liquid’s temperature-dependent
vapor pressure and it’s LEL.
Vapor
LEL LEL
Vol.-% g/m3
Acetone
2.5
2.8
Acrylonitrile
Benzene
1.2
n-Butanol
1.7
n-Butyl acetate
1.2
n-Butyl acrylate
1.2
Chlorobenzene
1.3
Cyclohexane
1.0
Cyclopentane
1.4
1.2-Dichloroethane (EDC) 6.2
Diethyl ether
1.7
1.4-Dioxane
1.9
Epichlorohydrin
2.3
Ethanol
3.1
Ethyl acetate
2.0
Ethyl benzene
1.0
n-Hexane
1.0
Methanol
6.0
1-Methoxy-2-propanol
1.8
Methyl ethyl ketone (MEK) 1.5
Methyl methacrylate
1.7
n-Nonane
0.7
n-Octane
0.8
n-Pentane
1.4
i-Propanol (IPA)
2.0
Propylene oxide
1.9
Styrol
1.0
Tetrahydrofuran (THF)
1.5
Toluene
1.1
Xylene (isomeric mixture) 1.0
Gas
LEL
Vol.-%
Acetylene
Ammonia
1.3-Butadiene
i-Butane
n-Butane
n-Butene (Butylene)
Dimethyl ether
Ethene (Ethylene)
Ethylene oxide
Methane
Methyl chloride
Propane
Propene (Propylene)
Hydrogen
2.3
15.4
1.4
1.5
1.4
1.2
2.7
2.4
2.6
4.4
7.6
1.7
1.8
4.0
60.5
61.9
39.1
52.5
58.1
64.1
61.0
35.1
40.9
255.7
52.5
69.7
88.6
59.5
73.4
44.3
35.9
80.0
67.6
45.1
70.9
37.4
38.1
42.1
50.1
46.0
43.4
45.1
42.2
44.3
Flash
Vapor
Ignition
Point Pressure Temperature
in °C at 20°C
in °C
in mbar
< -20
246
535
-5
117
480
-11
100
555
35
7
325
27
11
390
37
5
275
28
12
590
-18
104
260
-51
346
320
13
87
440
-40
586
175
11
38
375
28
16
385
12
58
400
-4
98
470
23
10
430
-22
160
240
9
129
440
32
12
270
-10
105
475
10
40
430
31
5
205
12
14
205
-40
562
260
12
43
425
-37
588
430
32
7
490
-20
200
230
6
29
535
25
7
465
LEL
g/m3
Ignition
Temperature
in °C
24.9
305
109.1
630
31.6
415
36.3
460
33.9
365
28.1
360
51.9
240
28.1
440
47.8
435
29.3
595
159.9
625
31.2
470
31.6
485
3.3
560
Only flammable
liquids have a
flash point
By definition,
there are no
flash points
for flammable
gases.
Flammable Gases and Vapors
LEL and Preventive Explosion Protection
Flammable gases and vapors can form flammable mixtures
when combined with air, but only if the proportion of flammable
gas and oxygen (or air) is within certain limits.
The lower explosion limit (LEL) is
defined as the concentration of
combustion gas (given in Vol.-%) in
a combustion gas-air mixture which,
under standard conditions, can be
ignited and will continue to burn.
The LEL of all known flammable
gases and vapors is in the range of
approximately 0.5 to 15 Vol.-%. For
example, the LEL of hydrogen-air
mixtures is 4 Vol.-%, and thus a test
gas with 2 Vol.-% hydrogen in air
can definitely not be ignited.
Concentration limitation
This behavior is very important for
practical explosion protection: If a
flammable gas cannot be ignited
below its LEL concentration,
explosion protection can be performed
by continuously measuring the gas
concentration and taking appropriate
measures to ensure that, for example,
half of the LEL (= 50% LEL) is
never exceeded.
This method of preventive explosion
protection is often known as the
primary measure: it reliably prevents
the forming, but not the ignition, of
a potentially explosive atmosphere.
For this purpose, concentration
measurement is preferably performed
using infrared or catalytic bead
sensors, which must comply with
standardized safety requirements.
LEL and Preventive Explosion Protection
ST-3101-2004
Flash Point of Flammable Liquids
Although we speak of flammable liquids, it is not the liquid,
but the vapor that is flammable. Only vapor can form a
flammable mixture with atmospheric oxygen. Both the volatility
of the vapor and its lower explosion limit (LEL) are measures
for the risk of explosion. These are described by the flash point.
To even be ignitable, the concentration
of the liquid’s vapor above the liquid’s
surface must exceed the LEL. The
amount of vapor generated determines
whether or not it ignites. The vapor
pressure, which is dependent on the
liquid’s temperature, is responsible
for this. With respect to the safety
of flammable goods, this behavior
is described by the flash point (F):
The flash point is the temperature
at which enough vapor is produced
for the vapor-air mixture to be ignited
by a standardized apparatus.
For example, if the flash point of
a flammable liquid is above 50 °C,
this liquid definitely cannot be ignited
at 30°C.
60 °C
Cyclohexanol
Dimethylformamide
50 °C
Trimethylbenzene
Ethylene Glycol
40 °C
n-Butanol
30 °C
n-Nonane
Chlorobenzene
Ethylbenzene
20 °C
i-Butyl Acetate
Ethanol
10 °C
Methanol
Toluol
0 °C
Acetonitrile
Ethyl Acetate
– 10 °C
Methyl Ethyl Ketone
Cyclohexane
– 20 °C
n-Hexane
Allylamine
– 30 °C
You cannot ignite diesel
(F > 55°C) with a burning
match, but you can ignite
gasoline (F < -20°C)!
In conclusion, the lower the flash point of a flammable liquid is, the
more dangerous it can be. Since vapors of flammable liquids cannot
be ignited below their flash point, preventive explosion protection
can also be implemented by using liquids with a flash point
significantly higher than the ambient temperature.
Although this is the common practice, when liquids are used as
solvents there is a disadvantage: less volatile liquids require more
energy for evaporation.
By definition, gases do not have a flash point because they have
no liquid phase under normal conditions.
Flash Point of Flammable Liquids
Concentrations And Their Calculation
Concentrations are specified as the percentage of a substance in
a reference substance. In regards to the measurement of hazardous
substances in the air, a concentration is used to define the quantity
of the substance in reference to air. A corresponding dimension is
used in order to gain simple, manageable figures for the specification
of a concentration. High concentrations are generally specified in
percent by volume (Vol.-%). This corresponds to a defined amount
of the substance in 100 parts air, for example air consists of
21 Vol.-% oxygen (100 parts air contain 21 parts oxygen).
For small concentrations, the measurement units parts per million
(ppm or mL/m3) or parts per billion (ppb or µL/m3) is used.
The concentration specification ppm means 1 part substance in
1 million parts air (in comparison: 1 sugar cube in a tanker). The
concentration specification ppb means 1 part substance in 1 billion
parts air (in comparison: 5 people in the entire population of the
earth). The calculation for this very small concentration in Vol.-%
results in this simple relationship:
1 Vol.-% = 10 000 ppm = 10 000 000 ppb
In addition to gaseous components, air can also contain "dissolved"
solid or liquid substances also known as aerosols. Because these
air-transported drops or particles are smaller, a volume specification
is not used. The concentration of aerosols is specified in mg/m3.
Vol.-% ppm
10 L/m3
Vol.-% =
1
1 cL/L
3
mL/m
ppm =
10-4
µL/L
µL/m3
10-7
ppb =
nL/L
g/L
104
107
1
103
10-3
1
3
mg/L mg/m
10 L/m3
g/L =
1
1 cL/L
mL/m3
mg/L =
10-3
µL/L
µL/m3
10-6
mg/m3
nL/L
103
106
1
103
10-3
1
Calculation mg/m3 – ppm
Molar volume
c
[ppm]
=
ppb
c
Molar mass
Because each volume is connected
to the respective mass, the socalled volume concentrations of
gaseous substances can be
converted into mass concentrations
and vice versa. However, these
calculations must be specified
for a certain temperature and a
certain pressure, as the gas
density is dependent on these
two environmental aspects. For
measurements at workplaces,
20°C and 1,013 hPa are usually
specified as the reference
parameters. The calculation takes
place using simple formulas.
The molar volume of a gas is
24.1 L/mol at 20°C and 1,013 hPa.
The molar mass of a specific gas
should be adapted dependent on
that gas.
Molar mass
c
[mg/m3]=
c
Molar volume
Concentrations And Their Calculation
D-23718-2010
Dräger-Tube®
Today, gas detector tubes are one of the classic measurement
methods for gas analysis. This versatile system can be used
within numerous applications in industrial fields, the fire
service and hazardous material control in laboratories, for
environmental research and many other areas.
Dräger-Tubes can be schematically classified utilizing the following criteria:
Gas measurement with Dräger-Tubes
Short-term tubes
D-16393-2009
Lab
analysis
Suction characteristic of
Dräger accuro®
Dräger accuro®
Dräger-Tube®
D-27831-2009
The Dräger-Tube measurement
system consists of a Dräger-Tube
and a Dräger pump. Each DrägerTube contains a very sensitive
reagent system that produces
accurate readings when the
technical characteristic of the
gas detector pump precisely
match the reaction kinetics of
the reagent system in the tube.
Therefore, a pump, delivering
the correct volume must also pull
the sample through the DrägerTube at the proper rate. These
requirements are referenced in
both international and national
detector tube standards or norms,
which require or recommend that
detector tubes be used with a
matching pump from the same
manufacturer.
Length-of-stain
indication
400
Lab
analysis
Direct
Indication
100
Color
comparison
Direct
Indication
n=10
Length-of-stain
indication
Direct
Indication
1000
Direct
Indication
Long-term tubes
Direct Indicating Dräger-Tubes
The principle is startlingly simple:
A test system, which reacts by changing color when it
comes into contact with a certain gas or vapor, is located
on a solid carrier material within an enclosed gas tube –
the Dräger-Tube. A defined quantity of ambient air is
suctioned through the tube using, for example, the
Dräger accuro pump. Even the smallest quantities of gas
are sufficient to trigger a reaction. The scale on the tube
allows the user to evaluate the concentration of the
hazardous substance directly after the measurement. For
applications in which single or less regular measurements
are sufficient, Dräger Tubes are particularly advantageous
compared to electronic detection devices, as they are
cheaper and easier to operate. The number of gases/vapors
that can be detected is also far higher than other detection
instruments with direct display.
n=10
n=10
100
100
400
400
1000
1000
2000
2000
3000
3000
4000
4000
D-16498-2009
Direct-indicating short-term tubes provide precise measurement
results directly after measurement. Time-consuming trips to the
laboratory are therefore unnecessary. Also, the tubes do not
require an additional calibration by the user. He receives the
calibration in the form of a scale on the tube. At present, more
than 220 short-term tubes are available for the detection of
up to 500 gases.
D-1344-2009
Long-term tubes with direct indication
In contrast to short-term tubes, no pump is necessary for sampling
with these measurement devices. The contaminant molecules
automatically move into the tube according to Fick’s First Law of
Diffusion. The driving force for this movement of the contaminant
molecules is the concentration differential between the ambient
air and the inside of the tube. Since the diffusion tubes do not
require a pump and go unnoticed when wearing, they are particularly
effective as personal monitors. Normally the measurements are
performed between 0.5 and eight hours. Long-term measurements
with diffusion tubes provide integrated measurements that
represent the average concentration during the sampling period.
Diffusion tube with direct indication in holder
Further information: Dräger-Tubes / CMS Handbook and the hazardous
substance database, VOICE (www.draeger.com)
Direct Indicating Dräger-Tubes
ST-1166-2004
Dräger Sampling Tubes & Systems
For the measurement of trace concentrations (e.g. in an office
or outside) or complex mixtures of substances (e.g. in workplaces),
a selective measurement with sampling systems and the
subsequent laboratory analysis is suitable. The complete
analysis can be forwarded to official positions or archived
for documentation purposes.
A differentiation is made between active and passive sample
collection:
Active sample collection:
For active sampling, the air to be evaluated is drawn through a sampling
tube with a pump (e.g. Dräger accuro pump). The substance to be
collected accumulates on the adsorbent (e.g. charcoal). The concentration is calculated from the mass of the hazardous material, which is
determined during the analysis, and the volume of the sample air.
Ci
mi
Ci
Grain of
activated
charcoal
Pump
Grain of
activated
charcoal
mi
Pump
D-16394-2009
mi
ci = ——– [mg/m3]
V
Passive sampling
In the case of sample collection using a diffusion sampler, the
contaminant molecules from the ambient air follow a defined
diffusion course and are immediately absorbed by the sorbent when
they reach the sorption layer. The mass of the adsorbed hazardous
substance is calculated in accordance with the first Fick law of
diffusion. Further details: Dräger-Tubes & CMS- Handbook and
the hazardous substance database, VOICE.
Ci
Ci (exterior)
Ci (interior)
Ci (exterior)
0
0
L
Sorption layer
L
∆ci =
D-16395-2009
D
mi · L
[mg/m3]
Di · t · A
²
A= D ·π
4
Grain of
activated
charcoal
Ci (interior)
mi
Dräger-Tube
Sample
Substance or group of substances,
collection type which can be collected
Activated charcoal tubes
Active
Aliphatic, aromatic hydrocarbons, solvent
vapors, ester, ketone, alcohols, glycol
ether, fluorinated hydrocarbons
ORSA diffusion sampler
Passive
Aliphatic, aromatic hydrocarbons, solvent
vapors, ester, ketone, alcohols, glycol
ether, fluorinated hydrocarbons
Silica gel tubes
Active
Strong ionic, organic connections, such as
alcohols, phenols, cresols
Amines sampling tube
Active
Aliphatic amine and dialkyl sulfate
Aldehyde sampling set
Active
Aldehyde, such as formaldehyde,
acetaldehyde, acrolein, glutaraldehyde
Isocyanate sampling set
Active
Isocyanate, such as HDI, 2.4 TDI, MDI
Nitrous oxide diffusion sampler Passive
Nitrous oxide
Dräger Sampling Tubes & Systems
ST-995-2004
Measurement Center & Analytical Services
The Dräger Analytical Services specializes in air examinations
in all areas, in which hazardous substances may be present.
These include:
– Workplaces, in which hazardous substances are dealt with;
– Offices and other interior spaces (e.g. nurseries, apartments,
assembly rooms, truck cabins, etc.), in which the air may be
contaminated by vapors from building materials or furnishings;
– Exhaust air from businesses and industrial plants
– Compressed air, soil gas in contaminated earth
– Gas emissions from material samples
Independent sample collection
Dräger offers suitable systems for inexpensive and independent
sample collection, consisting of Dräger pumps, collection media,
sample collection records and dispatch bags for the Analytical
Services. The collection systems used by the customer are closed
once the samples have been collected, and are sent to the Dräger
Analytical Services in Lübeck along with a sample collection record.
4. RESULT
Analysis
result
D-16396-2009
Analytical Services
1. COLLECTION
Sampling
2. ORDER
Sampling record
3. ANALYSIS
Analyze hazardous
substances
Air investigations at the workplace by sampling on site followed by laboratory analysis
Dräger Measurement Center
The Dräger Measurement Center, which is accredited in accordance
with DIN EN ISO/IEC 17025, offers a complete range of services for
the management of hazardous substances. The services provided
include consulting, measurement planning, execution of sample collection
and measurements on-site, analysis of samples, as well as the evaluation
of results in the form of a measurement report or survey.
Measurement Center & Analytical Services
Dräger CMS-Chip
The Dräger Chip-Measurement-System is a new generation of
chemical gas detection technology. Dräger CMS is a system
for quantitative determination of hazardous gas or vapor
concentrations in the air. The measurement is carried out in
the workplace to monitor for hazardous gas concentrations,
process control, and for measurements in confined spaces,
etc. This system is designed for short-term measurement.
The complete measurement system consists of two main
components:
– Substance-specific chips
– Analyzer
The chip
Each chip contains ten measurement capillaries filled with a substancespecific reagent system. Compared with other measurement systems,
chemical reagent systems have distinct advantages. One reason for
this is, that it is possible to supplement the reacting layer with one
or more pre-layers to adsorb moisture, to trap interfering substances,
or to convent substances into measurable substances.
This ensures that the measurement result is substance-specific.
The reactive preparations necessary for detection are kept in
hermetically-sealed glass capillaries until needed. The chip housing
also protects the capillaries from possible external, mechanical or
chemical influences.
When the chip is inserted into the analyzer all information required
for the measurement is transfered to the analyzer by means of
a bar code:
– the substance to be measured
– the measurement range
– the measurement time
– the parameters for the calibration function
– the required flow rate
Registration pin
BARCODE
contains:
6406070
D-16397-2009
· Chip type
· Measurement range
· Measurement time
· Calibration data
· Required flow
Seal
1000.25000 ppm
Kohlenstoffdioxid
Carbon Dioxide
Batch: ARJB-0001
Dräger
Measurement capillaries
Gear rail
The Chip
Futher information: Dräger-Tubes / CMS Handbook and the hazardous
substance database, VOICE (www.draeger.com)
Dräger CMS-Chip
ST-840-2004
Dräger CMS-Analyzer
The analyzer records the measurement effect optoelectronically,
thereby eliminating human factors. The gas inlet for the sample
air is located at the front of the analyzer and is protected from
dust and other impurities.
When the integrated mechanics have established an air-tight
connection between the entire gas conduction system and the open
capillary of the chip, a special pump system pulls a constant massflow of air through the capillary. The pump system consists of a
mass-flow controller, a processor and a small electric membrane
pump. The processor regulates the pump for the necessary
mass-flow. This combination supports an accurate mass-flow
and compensates for fluctuations in the ambient air pressure, within
certain limits. No correction of the measurement result is necessary,
regardless of whether the measurement is taken at the Dead Sea
or in the mountain air of Mexico City.
D-16398-2009
Schematic display of CMS
measurement principle:
The measurement principle of the CMS is based on a dynamic dose
measurement which is dependent on concentration. The basis for this
principle is chemical kinetics, whereby the speed of the chemical
reaction in the capillary depends on the concentration of the sample.
For the chip measurement system, this means defined and short
measurement times. The measurement time is not constant, but is
directly related to the concentration, i.e. the higher the concentration,
the shorter the measurement time. The corresponding position of
the optical unit allows a direct determination of the speed of the
chemical reaction within the capillary. Since concentration and
reaction speed are directly proportional, the analyzer terminates the
measurement very quickly when high concentrations are present.
Dräger CMS-Analyzer
ST-299-2001
Electrochemical Sensors
Many toxic gases are very reactive and can change their chemical
composition under certain conditions. An electrochemical sensor is
a micro-reactor, which produces a small but measurable amount of
current when reactive gases are present. As is the case with a
normal household battery, electrochemistry is involved because the
chemical reaction produces electrons.
An electrochemical sensor consists of at least two electrodes (the
measuring electrode and the counter electrode). These electrodes
have contact with each other in two different ways: on the one hand
via an electrically conductive medium called electrolyte (a liquid to
transport ions), on the other hand via an external electric circuit
(electronic conductor). The electrodes are made of a special material
that also has catalytic characteristics, enabling certain chemical reactions
to take place in the so-called 3-phase zone, where gas, solid catalyst
and liquid electrolyte are present. However, a dual-electrode sensor
(measuring electrode and counter electrode) has many disadvantages.
For example, should higher concentrations of gases be present, this
can lead to higher currents in the sensor and a voltage drop. The
voltage drop then changes the preconfigured sensor voltage. This, in
turn, can lead to the production of unusable measurement signals
or, in the worst case, a chemical reaction in the sensor that goes
unnoticed during measurement.
For this reason, the Dräger XS and XXS Sensors contain a third
electrode, the so-called reference electrode, which has no electrical
current and whose electric potential, therefore, remains constant.
This is used to continuously measure the sensor voltage at the
measurement electrode, which can be corrected by the sensor’s
internal control enhancement. This significantly improves measurement
quality (e.g. with regard to linearity behavior and selectivity) and
leads to a longer life time.
Futher information: Instrument & Sensor Handbook and the hazardous
substance database, VOICE (www.draeger.com)
Electrochemical sensor
CO-Molecule
Target gas, enters into the
measuring electrode
Porous
membrane
Electrolyte Reference Display
electrode
CO²-Molecule
Reaction product, leaves
the measuring electrode
H²O-Molecule
part of the electrolyte
H+ Hydrogen-Ion
positive charge (because
one electron is missing)
D-16399-2009
Oxygen atom
Oxygen-Molecule
from the ambient air
Gas
Electron
Chemical reaction at the measuring electrode
CO + H²O
CO² + 2H+ + 2e-
Measuring
electrode
Counter Micro-amp
electrode
meter
Chemical reaction at the counter electrode
½O² + 2H+ + 2e-
Electrochemical Sensors
H²O
Catalytic Bead Sensors
Under certain circumstances, flammable gases and vapors
can be oxidized with the oxygen within the ambient air and
release reaction heat. Typically, this is achieved through the
use of special and suitably heated catalyst material, which
slightly increases its temperature through the resulting heat
of reaction. This slight increase in temperature is a measure
for the gas concentration.
Within a porous ceramic bead (diameter under 1 mm), there is a
small platinum wire coil embedded. An electric current flows through
Catalytic bead sensors
H²O-Molecule
CO²-Molecule
O²-Molecule
D-16400-2009
Methane-Molecule
Flame
arrestor
Gas
Detector
element
Compensator
element
Reaction
CH4 + 2 O2
2 H2O + CO2 + heat of reaction
the platinum wire coil so that the pellistor is heated up to some
hundred degrees Celsius. If the pellistor contains the suitable catalytic
material, its temperature will continue to rise in the presence of
flammable gases, and the platinum wire coil’s resistance will increase
accordingly. This change in resistance can now be evaluated
electronically.
To eliminate any changes in the ambient temperature, a second
pellistor is used, which is very similar but does not respond to gas
(e.g. because the pellistor does not contain the necessary catalyst
material). Integrating both the pellistors in a Wheatstone bridge
circuit results in a sensor for detecting flammable gases and vapors
in the air, which to a large extent is independent of the ambient
temperature. Because the catalytic bead sensor contains hot
pellistors, it can (if the lower exposure level – LEL – is exceeded)
act as an ignition source. This is prevented by using a metal sinter
disk. If an ignition takes place in the interior of the catalytic bead
sensor, the sensor’s housing withstands the explosion pressure and
the flame is cooled down to below the ignition temperature of the
gas. This ensures that the flame can not leave the sensor housing.
Futher information: Instrument & Sensor Handbook and the hazardous
substance database, VOICE (www.draeger.com)
Catalytic Bead Sensors
Infrared Sensors
All gases absorb radiation in a characteristic manner, some
even in a visible range, for example 0.4 to 0.8 micrometers. This
is why chlorine is green-yellow, bromine and nitrogen dioxide
are brown-red, iodine is violet, and so on. However, these
colors can only be seen at high and lethal concentrations.
Hydrocarbons, on the other hand, absorb radiation in a certain
wavelength range, approx. 3.3 to 3.5 micrometers. Since the main
components of air – oxygen, nitrogen and argon – do not absorb
radiation in this range, this method can be used for measurement
purposes. In a closed container containing gaseous hydrocarbons
(e.g. methane or propane), the intensity of an incoming infrared light
will be weakened. This weakening is dependent on the concentration
of the gas.
IR sensor
Flame
arrestor
Methane molecule
absorbs IR light
D-16404-2009
Incoming
infrared light intensity
Reflector
Double
detector
Weakened
infrared light intensity
A methane molecule absorbs energy
and is caused to oscillate
Gas
IR transmitter
Reaction
CH4 + Energy
CH4 (charged)
Air: Infrared light passes through without weakening – Intensity
remains the same
Gas (e.g. methane): Infrared light weakens when passing –
reduced intensity corresponds to the concentration of methane.
This is the principle behind an infrared measuring instrument,
as used with Dräger Infrared sensors. Most flammable gases
and vapors are hydrocarbons, which almost always can be detectable
because of their characteristic behavior in regards to
infrared absorption.
Functional principle: The ambient air to be measured is guided to
the measuring cell by diffusion or through the use of a pump. From
the infrared transmitter, wide-band radiation finds its way into the cell
through a window. It is then reflected onto the mirrored walls, passing
through a window onto the double detector. The double detector
consists of a measurement and reference detector. If the gas mixture
contains hydrocarbons, then a part of the radiation is adsorbed and
the measurement detector produces a small electrical signal. The
reference detector’s signal remains unchanged. Fluctuations in the
performance of the infrared transmitter, contamination of the mirrors
and windows, as well as disruptions in the ambiet air caused by dust
or aerosols affect both detectors to the same degree, and, therefore,
are fully compensated.
Futher information: Instrument & Sensor Handbook and the hazardous
substance database, VOICE (www.draeger.com)
Infrared Sensors
PID Sensors
Many flammable gases and vapors are toxic to humans long
before they reach their lower explosion limit (LEL). For this
reason, an additional measurement of volatile organic substances
in the ppm range through the use of a PID sensor is an ideal supplement to the usual personal monitoring.
The air is drawn in through the gas inlet and into the measurement
chamber. There, a UV lamp generates photons, which ionize certain
molecules within the gas flow.
PID sensor
Electrode
Porous
UV lamp
membrane (current measurement)
M Gas molecule
M
M
M
e-
M+
e-
M
M
M
M+
D-16405-2009
M
M
Ultraviolet rays
Gas
Electrode
(suction voltage)
In order to ionize permanent gases in the air (such as inert gases,
nitrogen, oxygen, carbon dioxide, and water vapor), a relatively high
amount of energy is required. For this reason, these gases do not
disrupt the measurement of hazardous substances. Most organic
substances which can be regarded as hazardous substances (e.g.
hydrocarbons) are ionized and exposed to the electric field between
the two electrodes in the measurement chamber. The strength of
the resulting current is directly proportional to the concentration of
ionized molecules in the detection chamber. This makes it possible
to determine the concentration of the hazardous substance in the air.
Ionization energy and UV lamps
Ionization energy is measured in electron volts (eV) and specifies
how much energy is required to ionize or charge one molecule.
This ionization energy is substance-specific data, such as the boiling
point or pressure. In order to ionize a certain substance, the ionization
energy of that substance must be smaller than the photon energy
of the lamp used with the photo ionizsation detector (PID). Two
different types of lamp are commonly used: the 10.6 eV lamp and
the 11.7 eV lamp.
A PID is suitable for detecting entire groups of hazardous substances.
However, when calibrated accordingly, it can also be used to detect
an individual substance.
Futher information: Instrument & Sensor Handbook and the hazardous
substance database, VOICE (www.draeger.com)
PID Sensors
Selecting the Proper Measurement Method
Selecting the correct measurement principle is crucial to
identifying gas-related risks. Each measurement principle
has its strengths and limitations, and is optimized for certain
groups of gases (flammable/toxic gases and oxygen).
For this reason, one important question is which gases/vapors
occur at the workplace. It is generally possible to distinguish
between the following gas-related risks:
Risk of explosion
– Wherever flammable gases or vapors exist, there is always an
increased risk of explosion. This is typically the case in the
following areas: mining, refining, chemical industries, and many
more. Infrared and catalytic bead sensors are used here.
These sensors typically record the gas concentration in a lower
exposure level (LEL) range, but can also sometimes be used
for the 100 Vol.-% range.
Oxygen displacement / oxygen excess
– Oxygen displacement is life-threatening. Oxygen excess affects the
flammability of materials, up to the point where they can selfignite.
Electrochemical sensors are usually used for measuring oxygen.
The measurement range lies between 0 – 25 Vol.-% and up to 100
Vol.-%. Dräger-Tubes and CMS can also be used here.
Toxic gases
– Toxic substances can occur anywhere. In industrial manufacturing
and treatment processes, during transport (rail, road or ship),
during incomplete combustion, and also during completely
natural processes such as decomposition and decaying
processes of waste materials.
Various different measurement principles can be used to detect
toxic gases.
– Dräger-Tubes
– CMS
– Electrochemical sensors
– PID sensors
How to identify the right principle for a certain application depends
on several factors, such as:
– What other hazardous substances are present (cross sensitivities)
– Is it necessary to selectively measure hazardous substances,
or does it make more sense to measure a total parameter
– Is short-term, long-term, or continuous measurement to be used
– Is it necessary to have warning and alarm functions when limits
are exceeded
Selecting the Proper Measurement Method
Application Areas for Portable Gas Detection
Portable gas detection instruments are subject to very diverse
requirements. Different application areas require solutions
tailored to the measurement task, which also take into account
the respective application conditions.
It is generally possible to distinguish between the following application
areas:
Personal monitoring
– The instruments should warn the wearer of gas-related risks in
his/her immediate work area. They are usually worn directly on the
work clothing. The basic requirements for these types of devices
are, therefore, a high degree of comfort, robustness and reliability.
Continuous detection devices for single gases or multiple gases
are suitable for this measurement task. For short-term measurements
(or spot measurements), Dräger-Tubes and CMS can also be used.
Area monitoring
– The task here is to monitor an area, in which one or more workers
are active. The device is located in a central position, so that it
can optimally monitor the work area. Robustness, stability and
well-recognized alarms (visual and audible) are the basic
requirements here. Continuous measurement devices for multiple
gases should be used.
Confined Space Entry
– In order to perform maintenance or repair work, it is often necessary
to enter confined spaces. Limited space, a lack of ventilation and
the presense or development of hazardous substances result in
particularly high risks in these work areas. A clearance measurement
is required before entry. Multiple-gas detectors with corresponding
pumps and accessories, such as hoses and probes, are recommended.
After a successful measurement where no hazards have been
found, the same devices can then be used for continuous personal
monitoring while working within the confined spaces. Dräger-Tubes
and CMS are also suitable for spot measurements.
Leak detection
– Leakages can occur anywhere where gases or liquids are stored
or transported. It is important to identify these quickly in order to
take appropriate measures to prevent damage to people, the
environment and the facility. Detection instruments with corresponding
pumps must have rapid response times in order to detect even
slight changes in concentration. Extreme reliability is a minimum
requirement for these instruments.
Application Areas for Portable Gas Detection
Single-Gas Instruments
If the risk caused by toxic gases or vapors can be narrowed
down to a single gas or one conductive component, single gas
detectors and warning instruments are the ideal solution for
personal monitoring at the workplace. They are small, robust
and ergonomic. The devices are typically worn directly on
the worker’s clothing, close to the breathing area, without
restricting the workers’ freedom of movement. The instruments
continuously monitor the ambient air and issue an alarm
(visual, audible and by vibration) when the gas concentration
exceeds a limit preconfigured on the device. This allows
workers to react directly to risks should incidents occur
during standard operations, or if unforeseeable events occur
during maintenance and repair work.
DrägerSensor®
Dräger XXS Sensors
provide longer
operating times.
PPM
D-16406-2009
Large display
The clearly structured,
language-free display
shows all necessary
information at one
glance.
Robust housing
Impact-resistance
combined with an
ergonomic design.
H2S
Good visibility
Colored labels are
available to distinguish
the instrument at a
distance.
Dräger Pac® 3500 – 7000
The Pac 3500 – 7000 family is equipped with XXS sensors, which
are miniature electrochemical sensors. They allow for a smaller,
ergonomic instrument design. The sensor sits directly behind
a replaceable dust and water filter, which protects it against
environmental influences with negligible effects on the response
times. Besides accuracy and reliability, the response time is crucial.
The so-called t90 to t20 times provide information on how fast the
sensor reacts to changes in the concentration of a gas. Due to the
fast reaction time and very short diffusion paths, these sensors react
extremely quickly and display any gas-related risk immediately. The
sensor’s electrical signal with the help of electronics and software
is displayed as a concentration. Alarm thresholds are defined in
the device (A1 = prewarning / A2 = main alarm). If these alarm
thresholds are exceeded by the current gas concentration, then the
device emits a visual, audible and vibrating alarm. Robustness and
protection against explosive materials are two further important
factors when selecting the correct gas detection instrument.
Dräger X-am 5100
The Dräger X-am 5100 is designed for the measurement of the
gases / vapors hydrazine, hydrogen peroxide, hydrogen chloride and
hydrogen fluoride. These special gas hazards are difficult to detect
because they adsorb to different surfaces. The open gas inlet projecting from the device prevents that adsorbing surfaces are
between the gas and the gas sensor. A rapid response of the
proven XS sensors is thus also ensured for these special gases.
Single-Gas Instruments
ST-7070-2005
Multi-Gas Instruments
If different hazardous substances (Ex-Ox-Tox) occur in the work
place, it is advisable to use continuous measurement devices for
multiple gases. They make it possible to use different measurement
principles (infrared, catalytic bead, PID and electrochemical
sensors) in one device, thus taking advantage of the respective
strengths of each measurement principle.
The constellation of the sensors depends on the application in question.
Up to 6 gases can be detected in real-time and continuously. Besides
being used for personal or area monitoring, optional accessories also
allow multi-gas instruments to be used for clearance measurements
and leak detection.
Multi-gas instruments include Dräger X-am 1700, X-am 2000,
X-am 3000, X-am 5000, X-am 5600 and X-am 7000.
Gas measurement technology (example: Dräger X-am® 7000)
Selection from
25 different
Dräger sensors
Cover
Internal
sampling pump
with an IP 67
membrane
Warning function
Visual 360° and
>100 dB loud
multitone alarm
3 electrochemical sensor slots
Compatible with up to 25 different
electrochemical sensors
Large display
Clearly structured,
scratch-proof display
informs in plain text
Robust housing
Robust, waterproof
housing with standard
rubber protection
Multi-Gas Instruments
D-16407-2009
2 Sensor slots
Compatible with PID, IR Ex,
IR C02 and Cat Ex
Explosion Protection
Industrial processes very frequently involve flammable substances
and sometimes also flammable particles. In these areas, flammable
gases and vapors may be released on a process-related basis
(e.g. by relief valves) but also by unpredictable incidents. For
prevention purposes, these hazardous areas are declared as
Ex-areas (or “zones”), in which only equipment that is equipped
with a suitable type of explosion protection and certified
accordingly may be used.
Explosion protection is regulated worldwide. The basis for these standards,
according to IEC (international), CENELEC (Europe) and NEC 505
(North America) is very similar and is based on the “3-zone concept”,
which is also increasingly accepted in the USA.
Zone, according to
IEC, NEC 505
and EN
Zone 0
Zone 1
Zone 2
Dangerous, explosive
atmosphere is present...
continuously, regularly, or long-term
occasionally
rarely and short-term
The typical American method of explosion protection, in accordance
with NEC 500, is based on the “2-divisions concept”:
Division, according to
NEC 500
Division 1
Division 2
Dangerous, explosive
atmosphere is present...
continuously or occasionally
rarely and short-term
According to IEC, NEC 505 and EN there are seven standardized
types of protection for electrical equipment in zone 1, while in North
America (USA/Canada) there are only three types of explosion
protection for division 1 according to NEC 500:
Type of protection,
according to IEC,
NEC 505 and EN
Explosion/Flame proof
Encapsulation
Powder/Sand filling
Oil immersion
Artificial ventilation
Increased safety
Intrinsic safety
Comparable
type of protection,
according to NEC 500
Explosion proof
–
–
–
Purged / pressurized
–
Intrinsically safe
The standardized marking of a gas detection device, e.g. Ex de IIC
T4, informs the user about the applicability in a designated
hazardous area.
Explosion Protection
ATEX 95 – European Directive 94/9/EG
Also known as ATEX 95 (formerly ATEX 100a), mandatory in
the European Union (EU) since July 1, 2003. Equipment and
protective systems for use in potentially explosive atmospheres
need to fulfill the Essential Health and Safety Requirements
(EHSR) which are assumed to be met when based on certain
harmonized standards.
0158
Notified body concerning production and quality
EU-requirements are met
Marking (according to ATEX):
I M 2 / II 2 G
Category
Type of potentially explosive atmosphere:
G: Gas, vapor; D: dust
I: Mining
II: Industry
complies with the directive 94/9/EC
Explosion protection:
Ex d ia IIC T4 Gb
EPL (Equipment Protection Level) G = gas
D = dust; a = Zone 0; b = Zone 1; c = Zone 2
Temperature category
i = Intrinsic safety
a = covers 2 faults
b = covers 1 fault
c = covers the normal use
Ignition protection: Pressure-resistant encapsulation
Explosion protected equipment
Explosion group:
I: mining, II: Eeverything
except mining
Subgroups IIA, IIB
and IIC: categorization
of gases depending
on their ignitibility
EC type examination certificate:
BVS 10 ATEX E 080X
X: Special conditions
U: Ex-component
Number of certificate
Complies with European Directive 94/9/EG
Year of the EC certificate’s publication
Notified body having type-approved equipment
Device categories and safety requirements:
Device group
I (Mining)
II (Industry)
Category
M1
M2
1
2
3
Safety
Very high
High
Very high
High
Normal
ATEX 95 – European Directive 94/9/EG
ST-334-2007
ATEX 137 – European Directive 1999/92/EG
Also known as ATEX 137 (formerly ATEX 118a), mandatory
in the European Union (EU) since June 30, 2006, addressed
to employers and end users concerning the minimum
requirements for health and safety for workers in potentially
explosive atmospheres.
Zone definition:
Gas,
Zone
Zone
Zone
Vapor
0
1
2
Dust
Explosive atmosphere is present...
Zone 20 continuously, long periods or frequently
Zone 21 occasionally, likely to occur
Zone 22 infrequently and for a short time only
Selection of equipment (this table is the link between
the categories of ATEX 95 and the zones of ATEX 137):
Operation allowed
Devices of category
Devices of category
Devices of category
for
1
2
3
Gas, vapor (G)
in zone 0, 1, 2
in zone 1, 2
in zone 2
Dust (D)
in zone 20, 21, 22
in zone 21, 22
in zone 22
Example: In zone 21 in the industry, where explosive atmospheres
caused by dust are likely to occur, the instruments to be used need
to have a marking II 2D or II 1D.
Necessary measures:
– Assessment of the risk of explosion
– Classification of the hazardous area into zones
– Marking of the hazardous places by means of a triangular
warning sign “Ex”
– Adequate safety measures
– Explosion protection documentation
– Competence of employees
– Criteria for a permit-to-work system for dangerous work areas
Guideline for risk reduction:
– Prevent the formation of explosive atmospheres,
or, if this is not possible:
– Avoid the ignition of the explosive atmosphere,
or, if this is not possible:
– Minimize harmful effects of explosions to a tolerable degree.
ATEX 137 – European Directive 1999/92/EG
Requirements for Gas Detection Instruments
Since gas detection instruments and systems are products of
safety technology for industrial applications, they need to comply
not only with statutory requirements (e.g. explosion protection,
electromagnetic compatibility) but also with further requirements,
guaranteeing the product quality and reliability of gas detection,
even in harsh ambient conditions.
Explosion protection standards:
Design requirements ensure that gas detection devices do not
act as a source of ignition. Internationally accepted standards
are IEC, EN (ATEX), CSA, UL, GOST, etc.
Protection types in accordance with EN 60529 (IP code)
The IP code provides information concerning the protective
properties of the housing against foreign bodies and water.
IP = ingress protection
Excerpt in accordance with DIN EN 60529:
D-16408-2009
First Protection against
index number solid foreign objects
Second Protection against
index number water
5
Protection against contact.
Protection against interior
dust deposits
5
Protection against
projected water from
any angle
6
Complete protection
against touch. Protection
against dust penetration
6
Protection against
penetrating water during
temporary flooding
7
Protection against
penetrating water during
temporary immersion
Protection class IP 67 guarantees a high degree of robustness. This
can, however, also have negative consequences when it comes to
vapor permeability. For this reason, the MEWAGG (working committee
for detection and warning devices for hazardous gases) within BG
Chemie (German institution for statutory accident insurance and prevention in the chemical industry)recommends users, who do not simply want to detect gases such as methane and propane, but also higher hydrocarbons or solvents, to have the manufacturer confirm the
suitability of the device. This can, for example, be the measurement
certificate in accordance with ATEX.
Quality of measurement functions
Compliance with predefined measurement quality, even under extreme
ambient conditions (temperature, pressure, wind, humidity, vibration, etc.)
EN 45 544
– for toxic gases and vapors
EN 50 104
– for oxygen
EN 60 079-29-1 – for flammable gases and vapors
Electromagnetic compatibility in accordance with EN 50270
Electrical or electronic devices should not be affected or disrupted
by electrical, magnetic or electromagnetic fields. For example, the
use of a mobile phone or 2-way radio close to a gas detection
instrument must not disrupt the instrument’s measurement signal,
and vice versa. Electromagnetic compatibility directives and standards
provide evidence and confirmation of immunity to interference and
low transient emissions.
Requirements for Gas Detection Instruments
ST-1005-2004
Calibration
The calibration of gas detection instruments is extremely
important. Obviously gas detection instruments cannot
measure correctly if they are incorrectly calibrated.
Dräger-Tubes and CMS
These two detection instruments are delivered calibrated. Until the
actual measurement, or until the expiration date, the hermetically sealed
glass tube ensures that the calibration remains stable, providing that
the storage conditions printed on the label are adhered to.
Sensors / portable gas detection instruments
Sensors are used for continuous measurements. Environmental
influences or other gases can change the calibration with which
the sensor is delivered to the customer. BG Chemie therefore
recommends regular checks / calibrations in its data sheets T021
(gas warning equipment for toxic gases/vapors) / T023 (gas
warning equipment for explosion protection). For the members
of the European Union, the relevant standard is EN 60079-29-2
or for international use IEC 60079-29-2.
While zero calibration is rather simple because the ambient air can
be used in most cases for this purpose, calibration of the sensitivity
(or span calibration) is not so trivial.
Electrochemical sensors must be calibrated with reactive gases for
the same reason why they can detect these gases. Unfortunately a
lot of reactive gases also react in low concentrations with (moist)
material surfaces and plastics. For this reason, it is important
to keep the passages between test gas and device as short as
possible. Therefore, manufacturers of gas detection instruments
provide calibration accessories that meet these requirements
and are optimized for their gas detection devices.
If, for safety reasons, the so-called target gas (the gas to be detected
during operation) is always to be used for calibration, there are also
many reasons to use an alternate test gas for calibration.
If a variety of gases are to be detected by just one sensor, the sensor
must be calibrated for the gas to which the sensor is the least sensitive.
The gas detector is then calibrated in the safest way, because all other
gas concentrations are regarded as too sensitive.
Test gases are provided as single gases and also gas mixtures for
calibrating multi-gas detectors.
Calibration
Dräger VOICE – Hazardous Substance Database
The risk to humans through a variety of hazardous substances
at the workplace and in the environment is increasing inexorably
in our technology-oriented society.
Rapid, comprehensive information that can be accessed at any
time plays a crucial role in implementing the correct measures.
The extensive database Dräger VOICE provides you with up-to-date
information on more than 1 700 hazardous substances and 11 500
synonyms.
Dräger VOICE is characterized in particular by the clear links between
hazardous substances, measurement options and protective equipment.
Information on the proper handling of the recommended products
provides additional safety while using.
A wide range of constantly updated substance information is
available for every selected substance:
– Current national and international limit values
– Chemical/physical information (formulas, vapor pressure, melting
and boiling points, etc.)
– Fire protection information (LEL, UEL, flashpoint, ignition point, etc.)
– Identifiers (CAS No., UN No., EC No.)
D-27830-2009
The Dräger VOICE hazardous substance database is available
online at www.draeger.com/voice.
Dräger VOICE: Hazardous Substance Database
Dräger VOICE – Hazardous Substance Database
Properties of Dangerous
Gases and Vapors
Flammable and toxic gases and vapors may occur in many
places. Dealing with this risk and the danger of explosion –
this is what Dräger’s gas detection systems are for.
This brochure is meant to give a basic introduction to gas
detection technology, measuring principles and safety
concerns.
Measurement Principles
Dräger offers a number of instruments with a diverse range
of measurement principles for detecting gases and vapors:
– Dräger-Tubes
– Dräger Chip Measurement System
– Electrochemical Sensors
– Catalytic Bead Sensors
– Infrared Sensors
– Photoionization Detectors (PID)
Usage and Requirements of
Gas Detection Instruments
Portable gas detection instruments must be able to reliably
detect a wide range of hazardous substances under changing
conditions. This places great demands on reliability, robustness
and flexibility, as the detection instruments are ultimately directly
responsible for the health and safety of employees. Not every
device can be used in every working atmosphere. Before using
a device, ensure that the device specifications are sufficient.
These requirements are defined in several standards and
directives.
Dräger Safety AG & Co. KGaA
Revalstrasse 1
23560 Lübeck, Germany
www.draeger.com
SUBSIDIARIES
AUSTRALIA
Draeger Safety Pacific Pty. Ltd.
Axxess Corporate Park
Unit 99, 45 Gilby Road
Mt. Waverley Vic 3149
Tel +61 3 92 65 50 00
Fax +61 3 92 65 50 95
CANADA
Draeger Safety Canada Ltd.
7555 Danbro Crescent
Mississauga, Ontario L5N 6P9
Tel +1 905 821 8988
Fax +1 905 821 2565
P. R. CHINA
Beijing Fortune Draeger Safety
Equipment Co., Ltd.
A22 Yu An Rd, B Area,
Tianzhu Airport Industrial Zone,
Shunyi District, Beijing 101300
Tel +86 10 80 49 80 00
Fax +86 10 80 49 80 05
FRANCE
MEXICO
Draeger Safety S.A. de C.V.
Av. Peñuelas No. 5, Bodega No. 37
Fraccionamiento Industrial
San Pedrito
Querétaro, Qro México
Tel +52 442 246-1113
Fax +52 442 246-1114
NETHERLANDS
Dräger Safety Nederland B.V.
Edisonstraat 53
2700 AH Zoetermeer
Tel +31 79 344 46 66
Fax +31 79 344 47 90
REP. OF SOUTH AFRICA
Dräger South Africa (Pty) Ltd.
P.O.Box 68601
Bryanston 2021
Tel +27 11 465 99 59
Fax +27 11 465 69 53
SINGAPORE
Draeger Safety Asia Pte Ltd
67 Ayer Rajah Crescent #06-03
Singapore 139950
Tel +65 68 72 92 88
Fax +65 65 12 19 08
SPAIN
Dräger Safety Hispania S.A.
Calle Xaudaró 5
28034 Madrid
Tel +34 91 728 34 00
Fax +34 91 729 48 99
Dräger Safety France SAS
3c route de la Fédération,
BP 80141
67025 Strasbourg Cedex 1
Tel +33 3 88 40 59 29
Fax +33 3 88 40 76 67
UNITED KINGDOM
ITALY
USA
Draeger Safety Italia S.p.A
Via Longarone 35
20080 Zibido San Giacomo (MI), Italy
Tel +39 02 90 59 49 1
Fax +39 02 90 00 36 86
Draeger Safety UK Ltd.
Blyth Riverside Business Park
Blyth, Northumberland NE24 4RG
Tel +44 1670 352-891
Fax +44 1670 356-266
Draeger Safety, Inc.
101 Technology Drive
Pittsburgh, PA 15275
Tel +1 412 787 8383
Fax +1 412 787 2207
90 46 736 | 03.12-2 | Marketing Communications | PP | LE | Printed in Germany | Chlorine-free – environmentally compatible | Subject to modifications | © 2012 Drägerwerk AG & Co. KGaA
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