Refrigerant Leak Detector testo 316-4. The testo allows for quick and reliable detection of leaks for R134a, R22, R404a, H², and all common refrigerants such as CFCs, HFCs, or HCs. The sensor is continuously monitored and displays any malfunctions or contamination. This eliminates the need for test leaks. In case of contamination, the sensor can be easily cleaned and is immediately ready for use again. The display changes from green to red in the event of a leak. An acoustic signal additionally indicates detected leaks. The peak hold function shows maximum leaks, making it easier to locate leak points. The flexible gooseneck allows for optimal positioning of the sensor close to the piping or measurement site. A simple sensor replacement by the user makes the testo 316-4 an ammonia leak detector with the optional NH³ sensor.