With zero global warming potential and zero ozone depletion potential, Ammonia is considered one of the most cost effective, energy efficient, natural refrigerants for industrial refrigeration. However, Ammonia is classified as a B2 refrigerant under the ISO 817 classification scheme, meaning it has higher toxicity and flammability than other A1 and A2L refrigerants.

Ammonia leak detection locations

Although Ammonia refrigeration plant locations in a typical room may have small leaks, these may be significant enough to cause a toxic hazard to personnel, and therefore sample locations/detectors should be located in the breathing zone, 1.5m from the ground, with an alarm level of 35 PPM. Typically, these same breathing zone sample locations/detectors will have the high alarm set at the 500 PPM level in accordance with EN378. However, locating the detectors intended for the 500 PPM alarm level may require a survey to be carried out as the breathing zone height may not always be applicable. Detecting this 500 PPM level is very difficult due to the nature of Ammonia as it may simply rise past diffusion gas detectors. Typically, small leaks of Ammonia rise and build up in the roof space of plant rooms at height. Therefore, the Lower-Explosive-Limit (LEL) sample points/detectors should be mounted within the roof space of the plant room to monitor for potentially hazardous levels of Ammonia in the LEL range, and set to alarm at the appropriate levels. Mounting an LEL Ammonia sample location/detector at lower level is not advisable. Typical mitigation to resolve Ammonia build-up would be to vent the roof space and force exhaust of the roof space to atmosphere.

Gas OEL (ppm) TWA STEL (ppm) IDLH (ppm) LFL/UFL (% Vol.) Alarm (ppm) Application
Ammonia (NH3 / R-717) 25 35 500 25 Personnel Safety
Ammonia (NH3 / R-717) 15% / 28% 500 Explosion Safety


Ammonia Leak Detectors

Multi-Zone Single-Zone MGS-400 Series MGS-550
MDL (ppm) 20 20 100 to 10,000 ppm / 100% LEL 100 to 10,000 ppm / 100% LEL
Sensor Channels up to 16 1 1 2
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