The Model C12-17 is a stand-alone 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 0-100% 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 relay is a latching alarm that can be reset with a magnetic tool without opening the enclosure.

C12-17 transmitters can be connected directly to PLC, DCS, or computer based alarm systems without additional hardware.

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.

A Gas Transmitter for the detection of Combustible Gases shall be provided to monitor the ambient gas concentration in ___________ (Specify Location). Each gas transmitter shall consist of an explosion proof enclosure rated for Class 1, Division 1, Groups B, C, & D. The Gas Sensor/Transmitter shall be the ATI Series B-12-17 Transmitter producing an isolated 4-20 mA analog output signal proportional to 0-100 % LEL combustible gas concentration (Lower Explosive Limit).

The Gas Transmitter shall measure combustible gas concentrations in atmosphere utilizing poison resistant catalytic bead sensor technology. Calibration shall be by zero and span potentiometers located on the transmitter PC board. For proposes of calibration, test loops for voltmeter connection shall be located on the transmitter PC board. Output shall be 4-20 mA analog loop powered, 10 to 28 VDC.

Optional

1. Each gas transmitter shall consist of a windowed transmitter enclosure with a viewable LCD display and adjustable 1 amp SPDT alarm relay and housed in an enclosure rated for Class 1, Division 1, Groups A, B, C, & D.
    
2. Each gas transmitter shall consist of an explosion proof transmitter enclosure with a remote sensor that can be located up to 50 feet from the transmitter. The remote sensor shall be provided with a permanently installed calibration adapter with a 1/8” barb fitting port for attachment of the calibration gas tubing and run to a convenient location close to the transmitter.