Dräger Sensor User Manual
Catalytic Bead DrägerSensor®
Sensors for Fixed Gas Detectors
The DrägerSensor® ... DQ detects ammable gases and vapours such as
hydrogen. Due to the double-detector compensation method, the catalytic
sensor is particularly long-term stable. The wire mesh at the gas inlet
serves as a ame barrier. So it ensures explosion protection at the same
time short response time.
Reference chamber with reference pellistorMeasuring pellistor
Flameproof stainless steel housing
Flame barrier
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02 | Catalytic Bead DrägerSensor®
Benets
The catalytic bead principle
The DrägerSensors ... DQ are based on the catalytic bead detection principle. The most important component
are the hot, catalytically active pearls on platinum coils (pellistors). These pellistors burn the gas and additional
heat of reaction is created. The temperature increases depending on the gas concentration and thus also
changes the electrical resistance of the platinum coils. This change is passed on as a measuring signal. There
are ve different catalytic bead sensors from Dräger, which are used in different transmitters and measuring
heads.
DrägerSensor® PR M DQ
PR stands for poison resistant. The pellistors of the DrägerSensor PR M DQ have a longer service life under
the inuence of poisonous substances. The sensor has a metric thread (M) on the back.
DrägerSensor® PR NPT DQ
The DrägerSensor PR NPT DQ also withstands poisoning substances for a long time. This sensor is equipped
with a NPT thread on the back.
DrägerSensor® HT M DQ
The DrägerSensor HT M DQ can be used at ambient temperatures of up to 150 ° C and is also approved
accordingly (HT = high temperature). This sensor also has a metric thread.
DrägerSensor® LC M
LC stands for >low concentration<. The DrägerSensor LC M detects very low gas concentrations in the
measuring range from 0 to 10% LEL. This is possible by a special arrangement of the PR pellistors, as well as
an amplier electronics. The sensor has a metric thread.
DrägerSensor® LC NPT
The LC NPT sensor also detects gas concentrations in the measuring range of 0 to 10% LEL. It is equipped
with a NPT thread.
System Components
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Catalytic Bead DrägerSensor® | 03
Dräger Polytron® SE Ex
The Dräger Polytron® SE Ex ... DQ sensing heads are gas detectors for
the continuous monitoring of ammable gases and vapours in the
ambient air. Measurement is based on the heat of reaction principle
where a chemical reaction takes place in a catalytic bead (also known
as a pellistor) inside the sensor.
Dräger PEX 3000
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The transmitter Dräger PEX 3000 detects ammable gases and vapours
in concentrations below their lower explosive limit. Its DQ-sensor
provides a long-term stable measuring signal and responds to gas
within a few seconds.
Dräger Polytron® 5200 CAT
The Dräger Polytron® 5200 CAT is a cost-effective explosion-proof
transmitter for the detection of ammable gases in the lower explosion
limit (LEL). It uses a catalytic bead DrägerSensor® Ex … DQ that will
detect most ammable gases and vapours. A 3-wire 4 to 20 mA
analogue output with relays makes it compatible with most control
systems.
Dräger Polytron® 8200 CAT
The Dräger Polytron® 8200 CAT is an advanced explosion-proof
transmitter for the detection of ammable gases in the lower explosion
®
limit (LEL). It uses a catalytic bead DrägerSensor
Ex … DQ that will
detect most ammable gases and vapours. In addition to a 3-wire 4 to
20-mA analogue output with relays it also offers Modbus and Fieldbus
protocols, making it compatible with most control systems.
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