Sauermann Si-RD3 Refrigerant Leak Detector The Sauermann Si-RD3 Refrigerant Leak Detector is a professional diagnostic tool for finding refrigerant leaks quickly across HVAC and refrigeration systems. A heated diode sensor detects common refrigerants including HFCs, HCFCs, R1234yf, R1234ze, R290, R600a, and 5% hydrogen/95% nitrogen tracer gases such as Nidron 5 and Trace-A-Gas. Three sensitivity modes — Low, Normal and High — allow the detector to be tuned to the job, whether hunting down a large leak or something much smaller. A 30cm flexible probe reaches into tight spaces around pipe joints, evaporators, compressors and service valves. Visual LED indicators and audible alarms give immediate feedback as gas levels rise, and an autozero function, resetting in as little as 1–10 seconds depending on leak level and sensitivity threshold,