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Hi, I have an old HPC 240v MOB 15E continuous running compressor and am wondering if I should add a pressure switch to the system? would this cause any problems? Would I need to modify or disconnect the offload valves? Thanks, Colin.
Colin, typically an air compressor with a pressure switch has an air tank that fills while the compressor is running.
When the cut out pressure is reached, the air compressor motor stops until the pressure in the tank drops to the cut in pressure and the compressor starts again to refill the tank.
A demand air compressor like your HSC rotary screw is not likely designed to have the motor start and stop, but rather, have the motor run continuously. An unloader valve in this type of compressor toggles the compressor to stop producing compressed air when it was not needed by the system and toggles air production on again when the system pressure level drops, all the while the motor is running.
As to adding a pressure switch, your system unloader circuit should be fulfilling this roll.
If your compressor has no air tank, then adding a “typical” pressure switch would likely mean that your air compressor motor would be cycling on an off very rapidly as the system air was consumed. That wouldn’t be good for the motor, I should think.
It is, of course, your compressor to do with as you wish.
Yet I wonder again about your question. What about your HSC air compressor is causing you to consider adding a pressure switch? Is this the Kaeser version? Perhaps you could provide a bit more information about the issue? Thanks.