Can two vacuum pumps be hooked up in tandem to achieve a significantly stronger vacuum? I ripped a compressor out of a dehumidifier earlier this evening, but it only pulls about 50mm Hg. I'm wanting a vacuum more in the range of 20mm Hg or stronger. I ask as I might be able to acquire another defunct appliance which has a functional compressor...

[This message has been edited by Smokey the Bear (edited 06-17-2003).]

smb try a fridge compresser thay will pull alot not sure about how much . but thay seam to work for all swims needs.

but it should pull more hooked tandem

[This message has been edited by pikk (edited 06-18-2003).]

Watch out for fridge compressors, most are piston types that seal with reed valves and won't pul much sustained vacuum, you can find rotary ones out there.

Also to increease absolute vacuum you must put your pumps in series. However you will run into an upper limit based on the vapor pressure of your oil and the pump design.

What kind of pump is in the dehumidifier?

I'm not sure, as I'm not familiar with pumps, and there isn't a label on it. It makes a puttering/purring noise when running, and when overturned, a non-volatile oil pours out of the gas entrance/exit tubes.