Bacharach QV2 2002-0001 Vacuum Pump for HVAC is a high performance 1.7 CFM AC vacuum pump. The Bacharach QV2 2002-0001 features an internal check valve to prevent oil from flowing backwards during a power loss, offset rotary vanes that work in conjunction with the vacuum pump oil in order to create high compression inside the pumping chamber, and a lightweight, but durable aluminum alloy motor casing.