Abstract: Refrigerant is recovered using a single pump unit, regardless of the refrigerant's phase. This is achieved by sensing the phase of the refrigerant and changing the pump's operation accordingly. The refrigerant phase can be sensed by a temperature-responsive element, such as a thermistor, or by other phase-sensing technology. In a preferred embodiment, the pump unit is a vane pump whose rotational speed is changed in response to the refrigerant's phase. If liquid refrigerant is sensed,, the pump operates at a lower speed. If gas refrigerant is sensed, the pump operates at a higher speed. The two speeds are chosen so that the pump will draw an EPA-specified vacuum on the refrigerant present. In other vane-pump embodiments, the pump's operation is changed by changing rotational speed.

Abstract: Refrigerant is recovered using a single pump unit, regardless of the refrigerant's phase. This is achieved by sensing the phase of the refrigerant and changing the pump's operation accordingly. The refrigerant phase can be sensed by a temperature-responsive element, such as a thermistor, or by other phase-sensing technology. In a preferred embodiment, the pump unit is a vane pump whose rotational speed is changed in response to the refrigerant's phase. If liquid refrigerant is sensed, the pump operates at a lower speed. If gas refrigerant is sensed, the pump operates at a higher speed. The two speeds are chosen so that the pump will draw an EPA-specified vacuum on the refrigerant present. In other vane-pump embodiments, the pump's operation is changed by changing the pump's mechanical configuration, rather than its rotational speed.