Service technicians involved in refrigeration recovery ask for minimum-size recovery units that still provide maximum performance. Manufacturers try to respond to that request with each new generation of equipment.

For instance, the Minimax by Promax is a recovery system that weighs 28 lb with an “oil-less” compressor that handles both liquid and vapor straight through the compressor.

Another product offered by the company is the RG5410HP oil-less refrigerant recovery system. It weighs 30 lb and works with both high- and low-pressure refrigerants. The compressor in the unit is compatible with all refrigeration oils.


Even though recovery requirements have been around for more than a decade, questions arise from technicians new to the industry and as the result of changing technology. Here are some frequently asked questions.

Q: Why is there still pressure left in a recovery unit?
A: The recovery process was not followed properly. The inlet and outlet valves were shut off after the unit was turned off. The valve must be shut off prior to turning off the unit.

Q: What does the term “oil-less compressor” mean?
A: An oil-less compressor is a compressor that doesn’t have oil in the crankcase. A car has oil in the crankcase. We are required to add and change the oil on a regular basis in a car. An oil-less compressor relies on the oil in the refrigerant itself. All refrigeration systems have an oil charge in the refrigerant that is required for the compressor of that particular system. That same oil in the refrigerant is what lubricates the compressor in an oil-less recovery unit.

Q: Which refrigerants can the above-mentioned recovery machines handle?
A: The recovery units can handle Category III, IV, V refrigerants based on the ARI 740 Standard. Generally speaking, they work with any approved refrigerant, up to 550 psi working pressure, other than R-717 (ammonia), alcobenzenate, or any hydrocarbon refrigerants (R-200) dependant on environmental/temperature conditions.

Q: What is the recovery rate of the RG5410HP unit?
A: It can do up to 13.96 lb/min liquid in push-pull, up to 0.37 lb/min for vapor, and up to 3.73 lb/min of direct liquid.

Q: What is the recovery rate of the Minimax unit?
A: It can do up to 13.00 lb/min liquid in push-pull, up to 0.34 lb/min for vapor, and up to 3.3 lb/min of direct liquid.

Q: How does the pressure selector switch on the RG5410HP work?
A: In the off position, you are using the 400-psi pressure cutoff sensor. In the on position, you are using the 550-psi high-pressure cutoff sensor.

Becker is a technical support specialist for Promax. For more information, call 800-327-5060 or 954-499-5400.

Publication date: 05/06/2002