CI21 Transmitter

Selective monitoring of ammonia in various applications

Ammonia is used as a refrigerant in many industrial areas. As it is highly toxic, corrosive and flammable, the gas needs to be monitored consistently. This is the only way gas leaks can be detected in time. The CI21 transmitter was designed specifically for NH3 measurement in applications with challenging environmental conditions. Its specialized measuring principle, Charge Carrier Injection (CI), is characterized by stable measurements, short response times and low cross-sensitivity.

The CI21 measures ammonia in small and large measuring ranges from few ppm to 10000 ppm (equivalent to 1% by volume). The sensor has almost no cross-sensitivities to gases that would trigger false alarms. This also applies to vapors from oils and cleaning agents, which are often found in applications where ammonia must be monitored. Hydrogen, which is produced during battery charging, does not affect the measurement signal either.

Resistant to external influences
The transmitter housing is made of aluminum. It is protected against the ingress of dust and splash water (IP54). The sensor can also be mounted remotely if the situation requires it. The cables used to connect it can be up to two meters long. The sensor is not susceptible to difficult environmental conditions. The CI21 can be used in temperature ranges between -35 and +55 °C, in dry and humid air (1 to 99 % RH).

Communication and service
The transmitter uses the analog industry standard (either 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 person.

Key features at a glance:

General information:

  • Measuring principle: Charge Carrier Injection (CI)
  • For ammonia
  • Optional remote sensor (maximum cable length: 2 m)
  • Expected sensor lifetime: 2 years
  • Signal transmission: 0.2-1 mA or 4-20 mA
  • Protection class: IP54

Optionally available:

  • Flow adapter, remote calibration adapter, weatherproof housing


Extensions and accessories

Weatherproof housing

Weatherproof housing for various transmitters
» more

Test gases

Find an overview of our test gases here
» more

Accessories CI21

Find the complete list of accessories for the CI21 here
» download PDF

Our experts are happy to answer your questions! How to find us