Dräger Sensor User Manual

Catalytic Bead DrägerSensor®

Sensors for Fixed Gas Detectors

The DrägerSensor® ... DQ detects fl 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 fl ame barrier. So it ensures explosion protection at the same time short response time.

	Measuring pellistor		Reference chamber with reference pellistor

Flameproof stainless steel housing

Flame barrier

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02 | Catalytic Bead DrägerSensor®

Benefits

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 five 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 influence 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 amplifier 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.

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System Components

Dräger Polytron® SE Ex

The Dräger Polytron® SE Ex ... DQ sensing heads are gas detectors for the continuous monitoring of flammable 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.

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Dräger PEX 3000

The transmitter Dräger PEX 3000 detects flammable 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 flammable gases in the lower explosion limit (LEL). It uses a catalytic bead DrägerSensor® Ex … DQ that will detect most flammable 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 flammable gases in the lower explosion limit (LEL). It uses a catalytic bead DrägerSensor® Ex … DQ that will detect most flammable 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.