The Refrigerant Compliance Glossary

A handheld instrument that detects refrigerant vapor at a joint or component, using heated diode, infrared, or ultrasonic sensing. The primary tool for pinpointing a leak once loss is known.

Annually. ALD systems require an annual audit and calibration to remain compliant, and the records must be retained.

The concentrations or loss quantities at which an ALD must alert — 100 ppm for direct detection, and 50 pounds or 10% of full charge for indirect.

Under AIM Act Subpart C, either calculate the leak rate within 30 days (120 for industrial process) and follow the full repair provisions if it is above threshold, or repair preemptively before adding refrigerant and then calculate.

An ALD that infers refrigerant loss from operating data — pressures, temperatures, liquid level, run time — rather than sensing refrigerant in air. Must alert at a loss of 50 pounds or 10% of full charge, whichever is less.

An ALD that senses refrigerant concentration in air using sensors near the compressor, evaporator, and condenser. Applies to indoor components, with detection at 10 ppm and alert at 100 ppm.

A permanently installed system that continuously monitors for refrigerant loss and alerts on it, either by sensing refrigerant in air (direct) or by inferring loss from system behavior (indirect). Direct systems must detect at 10 ppm and alert at 100 ppm; indirect systems must alert at a loss of 50 pounds or 10% of full charge, whichever is less.