This sensor uses a porous metal oxide with catalyst that is heated by a small internal heater.

The sensor exhibits a large decrease in resistance when exposed to NH3 gas, and gives a 4/20-mA output, non-linear.

This sensor has a long life, five to ten years.

The sensor life is shortened three to four months, if exposed continuously to interference gas. 

The sensor will normally become more sensitive as it ages.

The sensor has broad-spectrum characteristics, i.e., it will sense other gases, such as methane, products of combustion, propane, butane, ethylene, chlorine, hydrogen, carbon monoxide, some refrigerants, paint vapors, solvents etc...

It is best used for trip levels in the 150/300 PPM range, up to 1% (10,000 PPM), due to its sensitivity to other gases.

It requires modification if used in temperatures of -15° F or below.

Keep the sensor away from high moisture changes, i.e., defrost vapor and high air movement.

It should be checked with certified calibration gas at least once every six months.

This sensor is ideal for machine rooms with outside fresh air make-up where no other gases are present, i.e., carbon monoxide from cars or trucks.

It is good for isolated vessel rooms.

It is ideal for most attic spaces.

It is good for refrigerated rooms in which the floors are not washed with alcohol-based cleaners and where products are stored that do not give off gases.

DO NOT apply where smoked meats, bananas and other fruits or vegetables are stored.

Gas-driven lifts cannot be used around solid-state sensors.

It is NOT good for low PPM set points, below 150 PPM, wash down areas, food processing rooms, rooms where cleaning solvents are used, etc.