www.safetyandhealthmagazine.com/articles/gas-monitoring-transmitters-2

Gas monitoring transmitters

January 1, 2011
The 420 series gas monitoring transmitter uses patented sensors that are highly specific, fast responding, poison-resistant, and unaffected by moisture or temperature changes. The gas monitoring transmitter is compact, durable, explosion proof, and easy to maintain and operate. Ranges are available to detect gases in the low ppm, high ppm or percent LEL levels without sensor damage.
CEA Instruments Inc.