ATI’s Series D12 gas transmitter line now includes a versatile Infrared system that can be configured for LEL or select toxic gases. The D12-IR utilizes a compact IR sensor in a corrosion resistant housing with sintered flame arrestor to meet hazardous area classification requirements, and is suitable for most plant environments.

The D12-IR gas transmitter eliminates the poisoning problems inherent in catalytic bead sensors. While catalytic LEL sensors offer reliable service, the presence of silicon vapors, hydrogen sulfide, and halogenated hydrocarbons can quickly degrade sensor performance. Infrared sensing technology is not susceptible to these potential interferants, which means greater measurement stability and longer sensor life.

D12-IR transmitters can be factory calibrated for volumetric methane measurements in special applications. Ranges from 0-10% to 0-100% by volume are available. A separate sensor is also available for high percent level measurements of heavier hydrocarbons such a butane and propane.

The D12-IR transmitter can also be configured with Infrared sensor for carbon dioxide (CO₂) or nitrous oxide (N₂O) detection.  All sensor versions can operate in diffusion mode for ambient air or with a flow cell for pumped samples.

Because the IR sensor is always in an active state, the transmitter continuously monitors critical sensor functions and indicates any sensor problems, both on the display and via the analog output.

Transmitters are designed for operation in hazardous areas. The cast aluminum housing for the D12 transmitter is rated for Class 1, Division 1, Group B, C, D locations and is UL, FM, and CSA certified.

The transmitter is available with either HART™ or MODBUS™ protocol. The HART™ protocol supports the HART™ Universal and Common Practice Commands at 1200 baud using the Bell 202 FSK modem standard. The MODBUS™ protocol supports 9600 baud access to concentration and status information, and supports alarm setup and many other functions on either RS485 or RS232 (software selectable).

LEL/Toxic Gas Transmitters for the detection of                                     (Specify Gas) shall be provided to monitor and display ambient gas concentration in                                     (Specify location). Each gas transmitter shall consist of an explosion-proof electronic transmitter and explosion-proof infrared sensor. Gas transmitters shall be ATI Model D12-IR 3-wire type with integral LCD display or 3-wire type with integral LCD display with back light and alarm features.

Gas transmitters shall measure gas concentrations in the installation area using an NDIR (non-dispersive infrared) sensor. The sensors shall consist of an infrared light source, a detector, and a thermistor.  The light source is a thin wall tungsten filament lamp, with an MTBF of 100,000 hours, and is pulsed at 2 Hz.  The detector is a dual pyroelectric element design, with each element covered by an optical filter that will pass only a specific band of infrared radiation.  The heat generated by the lamp shall assist in keeping moisture from condensing in the sensor body, and on the detector.

The Gas Transmitter shall be housed in an explosion proof enclosure with window and consist of an electronic board stack with LCD graphic display with magnetic function switches for non-intrusive access to all transmitter programming and display functions.  The electronic board stack shall be designed to plug into a power supply board at the base of the transmitter enclosure and be easily removable for service or field wiring.  The transmitter shall display gas concentrations on an LCD graphic display along with alarm indication and menus for setup and operating parameters.

Gas transmitters shall operate from power supplies of 12-30 VDC, and shall be capable of driving external loads up to 675 ohms with a standard 24 VDC supply.  Transmitter enclosure shall be rated explosion-proof for Class 1, Groups B, C, & D. 

OPTIONAL:

Each gas transmitter shall be provided with three SPDT 5-Amp alarm relays that are assignable to any alarm setpoint or fault condition and be fully programmable for setpoint, hysteresis, and time delay.

Each gas transmitters shall be provided with HART^TM communication output supporting both 4-20 mA and constant current mode of operation.

Each gas transmitter shal be provided with Modbus^TM protocol and software selectable on either RS-485 or RS-232.