Rotary Vane Type Vacuum Pumps
The rotary vane type pump (see illustration), which has a small electric motor driving the pump, is considerably more expensive than a venturi type pump. It also requires some maintenance the pump must be routinely lubricated. But it doesn’t require the use of a compressor to evacuate the system, so it uses a lot less electricity than a venturi type.
To operate a rotary vane type pump:
1 Make sure the pump is free by rotating the shaft.
2 Remove the exhaust dome and fill the pump with oil to at least the mid-point of the oil level sight glass.
3 Make sure that the vacuum breaker O-ring valve is closed tight.
4 Make sure that the electrical power matches the motor wiring (normally 11 5 volts, but some pumps are 220 volt models).
5 Check all hoses and connectors for leaks. Use the shortest plumbing that will work.
6 Install a shut-off valve on the end of the service hose that will connect the pump to the test gauge manifold.
7 Connect the shut-off valve to the center service port of the manifold.
8 Start the pump. You will note a gurgling sound as the refrigerant passes through the pump. This should be followed by a short period of almost no sound coming from within the pump. The pump will then develop a rapping sound which only occurs when it’s under a deep vacuum (normally
250 microns or less).
9 After the system is pumped down to the desired vacuum level, close the shut-off valve and open the vacuum breaker valve until the pump makes a gurgling sound. Failure to break the vacuum within the pump at this time can result in damage to the pump when it restarts.
10 Turn off the motor.