Bill Palumbo Vacuum Rig

[mnrite@yahoo.com]

Bill

I built a vacuum pump similar to the one you recently did. I used an old compressor instead of a vacuum pump. With the same switch you used the system will pull to 20" and stay there but the pump never shuts off. I pulled the cap from the switch and tried turning the screw both ways, still never shut off. I have connected to the NC and C terminals, the NO terminal not used. Any ideas?

Thanks
Mike

[Brady Watson]

Yes...you either have leaks exceeding the CFM of the pump, or the screw is turned too far clockwise. Turn it CCW to lower the upper shutoff.

-Brady

[billp]

Mike,
I think Brady is right. Usually if you have a leak that is too large for the pump to keep up with it will run continuosly.I still have one tiny pinhole leak somewhere in my system which I'll try to hunt down this week, but my switch/pump setup gives me about 4-5 minutes before it loses enough vacuum to kick on, and even then it's only for 17 seconds...

[nappy1]

Mike,
Make sure the switch is wired correctly. If you are using the same switch as Bill you need to use the Com. ( C ) and normally closed (nc) contacts.
When you first start out, you have 4 wires. 2 from the motor and 2 from the power cord. If you have a green wire that is only for mechanical ground and never gets connected to a switch.
Now last of all make sure that one wire from the motor and one wire from the motor go to the contacts I mentioned. Only one wire on each screw. The other wires from the power cord and motor get twisted together and wire nutted.
If the pump never shuts off now and you had it correctly connected from the start you have a major leak, which should be visible on your vacuum gauge. The bad news is if you had a problem with the connection and tripped a circuit breaker, then the switch is destroyed and you need a new one.
FYI for all those making a vacuum setup, Grainger has a good switch. It is made by Square D, their part number is 2FP36.