Have you had experience with the start-up of the liquid ring compressors/vacuum pumps? Is it a fairly operator intensive start-up procedure? Can it be started on auto? or does it need more TLC from an operator to start-up? How much time would it take to start up a vacuum pump?

They are simple enough to be used in commercial carpet cleaning machines (the kind mounted in vans/lorries that come to your house and steam-clean your carpet).  Given that the lads who do this type of work are fairly low down the food chain, they can't be that user-unfriendly.

the key rules are:

1. never run the pump dry

2. do not start the pump over-flooded with water.


If you are running "once-thru" (without any recirculation of the seal liquid) then just open the seal liquid supply (solenoid valve) simultaneously with the vacuum pump / compressor motor.

In case of a recirulation the key issue is the level control in the discharge separator (always enough water in order not to run dry, but never higher than shaft level for the next automatic start.)

Never start the vacuum pump / compressor with a casing fully filled with water.
The water (in the compression chambers betwwen the blades) cannot be compressed,
the consequences will be shaft deflection and posssibly a pump ceasing.

A check-valve in the inlet or discharge piping may avoid the filling of the pump with liquid at shut-down (the system is still under vacuum but the discharge separator is at atm. pressure).

Ideally, with a good piping design, the seal liquid (after shut-down ) will communicate between separator and pump, to get an equlibrium at the right (shaft) level.
If it is not possible then add an equalization (liquid) line (1 inch) between discharge separator and vacuum pump casing.


It takes time to build a stable ring, from 20-30 seconds up to 2-3 minutes depending of starting conditions.

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