Bacharach QV5 2002-0005 Vacuum Pump for HVAC is designed with a two-stage pump in order to achieve a stronger vacuum pull. The Bacharach QV5 2002-0005 features offset rotary vanes that work in conjunction with the vacuum pump in order to create higher compression in the pumping chamber, a built-in check valve to prevent oil from flowing back into the system in the event of a power loss, ability to start in low temperatures via low starting torque, and more.