Quote:
Originally Posted by NiHaoMike
Vacuum on the Cheap - Refrigeration Compressors
So it looks like it is possible to build a good vacuum pump from refrigeration compressors. Just get two and not just one. The modern high efficiency ones should work even better since they have tighter tolerances for higher efficiencies.
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NiHaoMike, good info here.
And just in case anyone might miss it, your link also contained this link to a PDF with detailed but dated instructions to build your own vacuum pump:
http://www.belljar.net/fbleeconversion.pdf
And here is a link to HVAC vacuum pumps on ebay:
vacuum pump, great deals on on eBay!
Additionally, here is a link to vacuum pumps at Harbor Freight:
Harbor Freight Tools
Harbor Freight used to carry a 1.5 cfm pump which was cheaper than any in the above link, and would work fine, though more slowly.
And here's a discussion from an HVAC blog about how you can't/can/can't/can
build a vacuum pump from a refrig compressor:
Compressor ID for DIY vacuum pump - Refrigeration-Engineer.com forums
One of the posts (#14) is worth re-quoting:
Quote:
Did you ever measured that reached vacuum, with that compressor, is some decent amount below boiling point of water at that temperature?
Boiling point of water at 68°F is 0,3394 PSI.
You need a lot lower pressure to boil that moisture and suck that out of system.
You can not measure that vacuum with [Bourdon] gauges!
What is the point in vacuum drying if you cannot lower system pressure to boil water and then suck that evaporated moisture out?
Compressor is not designed to pull decent vacuum. You need rotary vane vacuum pump
Rotary vane pump - Wikipedia, the free encyclopedia
(preferably double stage capable of pulling to 50 microns => 0,05 torr => 0,000967 PSIa)
and electronic micron vacuum gauge to measure reached vacuum, and if water still boils.
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So, for HVAC work, it looks like 1 Torr is not quite low enough.
If you're going to build your own vacuum pump (or buy used), it would be advisable to get your hands on a micron gauge so you know for sure what kind of vacuum you are actually pulling.
Best Regards,
-AC_HAcker
P.S.:
The loop-field is 50% in and tested. Working like a demon to try to beat the rain.
After this project, I don't care if I never see a shovel again!
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