IR29 B Transmitter

With Modbus and infrared sensor for flammable gases

If flammable gases and vapors need to be monitored in Ex zones, the IR29 B transmitter is a reliable and robust solution. The IR29 B transmits measured values and status notifications via the RS-485 interface with Modbus protocol. Gases are monitored either on-site by diffusion or with pressureless gas supply using a flow adapter. In combination with one of GfG's reliable controllers, the IR29 B can be installed in new gas detection systems or retrofitted into existing ones.

The IR29 B uses non-dispersive infrared (NDIR) sensor technology to detect combustible gases and vapors. Our patented 4-beam and 4-wavelength technology with gold-plated mirror optics, which do not require any beam splitters, is used to ensure selective measurement results without false alarms. The installed infrared sensors can detect up to three gases simultaneously and also enable measurements above the lower explosion limit (LEL). They do not require oxygen and are not susceptible to sensor poisons. The long-life sensors make the IR29 B a permanently reliable solution for detecting a wide range of combustible gases and vapors in the measuring range of 0 to 100 % LEL. Its automatic temperature compensation and the linearization of the measurement signals ensure high measurement accuracy.

Communication and service
Signals are transmitted via the digital RS-485 interface (Modbus). Two status LEDs are used to indicate its operation status. Service and adjustments can be carried out on site using the optional RC2 remote control (one-person adjustment). The IR29B's self-monitoring function increases device safety between maintenance intervals. Measured values and incidents are automatically recorded by the transmitter in an internal ring buffer. Test gases for function tests and adjustments can be inserted using a calibration adapter.

Safety and instrument protection
The IR29 B is ATEX certified for use in Ex zone 1. It meets the standards of increased safety "e" and encapsulation "m". The housing made of V4A stainless steel and poly-carbonate is protected against the ingress of dust and water (protection class: IP67). Accessories include a guard plate and a dust filter.


Key features at a glance:

General information:

  • Measuring principle: infrared (IR)
  • For combustible gases and vapors
  • Not susceptible to sensor poisons
  • Expected sensor lifetime: 6 years
  • Signal transmission: RS-485 (Modbus)
  • Protection class: IP67
  • Integrated data logger

Approvals / Certifications:

  • ATEX certification: II 2G Ex eb mb ib [ib] IIC T4 Gb

Optionally available:

  • Pressure and humidity sensors, ex-proof control unit RC2, impact protection, flow adapter, calibration adapter, protection plate, dust filter, weatherproof housing, flow adapter

Detectable gases

LEL combustible gases
C2H2 Acetylene
C2H4 Ethylene
C2H6O Ethanol
C3H8 Propane
C3H8O n-Propanol
C4H10 n-Butane
CH4 Methane
Other gases on request.


Extensions and accessories

Weatherproof housing

Weatherproof housing for various transmitters
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Test gases

Find an overview of our test gases here
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Accessories IR29 B

Find the complete list of accessories for the IR29 B here
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