Compact, highly reliable, yet economical refrigerant leak monitoring system designed to monitor a single refrigerant in a single zone. Provides early audible and visual warning of refrigerant leakage with adjustable sensitivity settings between 100 to 1000 PPM with an auxiliary 1/2 HP N.O. and N.C. dry contact control function for operating an additional alarm or other safety device. Replacement sensors are interchangeable enabling the replacement of a failed sensor directly in the field without recalibration, minimizing downtime.