Quote:
Originally Posted by Geo NR Gee
New hacker question.......... When shopping for a vac pump, what level of HG should the pump be required to pull the system down to? I will be using it for R290, R134a, R22.
|
The pump should have a spec designating the maximum vacuum, and the unit for the spec is usually in microns.
For instance, the cheapo ($140) twin rotor Harbor Freight pump I got was rated at 60 microns, as I recall. I measured it with a micron gauge at 80 microns, and that was good enough for me.
A friend loaned me some well-worn vac pumps which only went down to about 500 microns, not good enough. He didn't have a micron gauge, he had a manifold set, and his vacuum gauge read 29.9 Hg, so he thought the vacuum pumps were perfect.
But at low vacuum, the manifold gauge will only read the really huge errors in vacuum.
And as I said before, you need to use fresh oil every time you evacuate your HVAC equipment... the oil is actually part of the process.
I think it's better for experimenter, amateur and hobby users to buy the oil in one or two use sealed containers. Only get the giant economy size oil if you are doing continuous production work, day after day.
Hope this helps.
-AC_Hacker