Model C12-17 Combustible Gas Transmitter from ATI


The Model C12-17 combustible gas transmitter designed to detect potentially hazardous concentrations of combustible gases in ambient air. Gases and hydrocarbon vapors such as methane, propane, butane, gasoline, toluene, hydrogen and many others can be reliably monitored in process buildings, analyzer enclosures, pump stations and gas compressor stations. In fact, anywhere gases or vapors may build up to explosive levels can be readily monitored using this transmitter.

C12-17 Combustible Gas Transmitters are three wire transmitters, operating from 24 VDC power supplies and transmitting a 4-20 mA signal proportional to 1-100% LEL (Lower Explosive Limit) of a particular gas or vapor. The transmitter is available either as a blind transmitter or with integral LCD display that provides local indication of gas concentration, visible through the glass window in the explosion proof housing. Units supplied with the integral display also contain a single alarm setpoint and relay for local alarm purposes. This integral is a latching alarm that can be reset with a magnetic tool without opening the enclosure.

C12-17 transmitter can be connected directly to PLC, DCS or computer based alarm systems without additional hardware. If complete alarm systems are needed, ATI can supply Series B14 modular alarm receivers or Series C14 multi-point scanning alarm units to provide all required alarm functions.

Sensor Operation

Combustible gas sensors are made up of two matched sensing elements, one active and one passive. Both are electrically heated and form two legs of a Wheatstone bridge circuit. When combustible gas contacts the sensor, the active element catalyzes the oxidation of gas, heating the active element and changing it’s resistance. The passive element remains unchanged, resulting in a change in the bridge circuit that is proportional to the gas concentration.

Explosion proof sensor assemblies are made of 316 stainless steel for maximum corrosion protection. A sinter bonded flame arrestor provides the gas diffusion path to the sensing elements while maintaining the flame proof integrity of the assembly. Sensing elements are specially designed for maximum poison resistance and long life in harsh industrial environments, with sensor life typically 2 years or more.


Gas Type Calibrated for methane unless otherwise ordered
Display 3 digit LCD optional
Range 0-100% LEL
Response Time T90 < 10 seconds
Accuracy Generally ±5% of value, but limited by available calibration gas accuracy
Electronic Repeatability ±1%
Electronic Linearity ±0.5%
Zero Drift Less than 2% full scale per month
Span Drift Less than 3% per month
Output Powered 4-20mA, 675 ohms max at 24 VDC
Power 12-30 VDC, 100 mA maximum
Enclosure Explosion proof, Class 1, Div 1, Groups B, C & D
Alarm Optional single alarm available
Alarm Relay SPDT, 5 Amp @ 220 VAC non-inductive latching
Sensor 316 stainless steel
Controls Potentiometer zero and span adjustment,
Potentiometer alarm setpoint adjustment,
Magnetic reset switch for latching alarm relay
Operating Temperature -40 to 70°C
Weight 3 pounds

Ordering Information

For pricing, please call AFC International at 1-800-952-3293, 219-987-6825 or fax 219-987-6826 or email


Model C12-17 Combustible Gas Transmitter literature

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