CS21 Transmitter

Versatile transmitter for refrigerants, toxic and flammable gases

If toxic or combustible gases need to be monitored outside of Ex zones, the CS21 transmitter is a good choice. It uses the reliable chemisorption principle to detect gases in different measuring ranges such as a few ppm or % LEL. The measuring method excels in long-term stability and good selectivity. The long lifetime of the sensor makes the CS21 an economical solution for monitoring gases in many applications.

The CS21 transmitter is ideal for selective monitoring of combustible or toxic gases. Since the CS21 can be used in temperature ranges from -30 to +55 °C, it is also suitable for monitoring refrigerants. An overview of the detectable gases, which are measured in different ppm ranges or in % LEL depending on the gas type, can be found at the bottom of this page.

Robust, versatile and durable
The aluminum housing of the CS21 is protected against ingress of dust and splash water (IP54). It can measure gases in dry air as well as in humid conditions (up to 96% RH). The sensor lifetime is typically at least five years. Due to the short response time of the sensor (depending on the type of gas), secureity measures can be initiated very quickly in case of an alarm. If necessary, the sensor can also be mounted remotely. The cables used to connect it can be up to two meters long.

Communication and service
The transmitter uses the analog industry standard (optionally 0.2-1 mA or 4-20 mA) signal to communicate the measured values to a controller for evaluation. Test gases for function tests can be inserted via an optional calibration adapter. On-site adjustment can be performed by a single technician.

Key features at a glance:

General information:

  • Measurement method: Chemisorption (CS)
  • For combustible and toxic gases
  • Optional remote sensor (maximum cable length: 2 m)
  • Expected sensor lifetime: 5 years
  • Signal transmission: 0.2-1 mA or 4-20 mA
  • Protection class: IP54

Optionally available:

  • Flow adapter, remote calibration adapter, weatherproof housing

Detectable gases

CH4 up to 90 % Natural gas
C2H4 Ethylene
C2H6O Ethanol
C3H3F5 1,1,1,3,3-pentafluoropropane (R-245fa)
C3H6O Acetone
C3H8 Propane
C4H10 n-Butane
C6H14 n-Hexane
C7H8 Toluene
C9H20 n-Nonane
CH2Cl2 Dichloromethane (R-30)
CH4 Methane
CH4O Methanol
CF3CH2F 1,1,1,2-tetrafluoroethane (R-134a)
CF3CH3 1,1,1-trifluoroethane (R-143a)
CO Carbon monoxide
NH3 Ammonia
Other gases on request.


Extensions and accessories

Weatherproof housing

Weatherproof housing for various transmitters
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Test gases

You can find an overview of our test gases here
» more

Accessories CS21

Here you'll find the complete list of accessories for the CS21
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