I just got a new Chicago Pneumatic QRS 7.5 hp. I know some of you out there have similar units and other rotarys. I am new to rotarys and don't know what's supposed to be normal.
The oil in the sight glass looks foamy while the compressor is running, and after the compressor shuts off there is a small slow squeak sound. Are these normal?
Also what do I need to fuse the unit, 40 AMPS? I can't find fuse sizes in the manual, it just says 36 amps max load.
At 36A you must be running 240V single phase. I would use 40A fuses of the type that can handle a brief inrush higher than 40A for motor starting. If you have it on a breaker 40A should handle the inrush.
My rotaries keep running and just the screw is unloaded so I cannot compare diectly with yours but when one of them unloads the screw there is a noise which I think is just the exit pressure venting so when it starts pumping again it is not starting on a load. Your squeak might be something similar; an unloader valve opening.
The sight glass for the oil is inside the housing on mine so I have never seen it while the machine is running. But I have seen foamy oil in other equipment and I think provided the machine is pumping correctl, there is no oil in the air and the oil in the sight glass settles down within minutes of the machine stopping I would not worry.