Gas alarms can detect small amounts of leaking in cold stores, machine rooms etc. where they can detect gas before harm is done are available for CO2 and ammonia.

A pH sensor can be used for detecting more than 100 ppm ammonia in water and glycol brines. For seawater and for high pH antifreeze it is possible to detect ammonia, but the leak must be large.

Compressor protection sensors are simple vapor quality sensors able to measure liquids in the suction line in front of the compressor. The sensor can deliver an alarm when liquid is detected and a continuous measurement of the liquid content. Both signal can be used to avoid liquid slugging in the compressor which can lead to severe damage.

CO2 leakage into ammonia is a challenge in cascade systems. If CO2 leaks in ammonia carbamate is created. This is a salt which blocks the pipes and ruins the system.