Quote Originally Posted by ultralo1 View Post
In the cascades that I work on the manufacturer recomends for a system with new oil that the vacuum holds below 200 microns for 20 minutes. if the system oil has ever had refrigerant in it then it changes to less than 500 microns for 20 minutes.

While at the manufacturers school they also preached about the triple nitrogen evac. Pull first vac to 2500 mic. break with nitrogen, pull to 1500, break with nitrogen, pull to 1000 then break, pull to desired vacuum. The reason behind the nitorgen breaks was that during evac water will turn to ice due to energy loss from vaporization. The nitrogen breaks will allow the ice crystals to melt back to water and then be boiled off.

I dont like POE oil. It seems like if it ever gets Hot it breaks down. Most of the compressor failures that we have seen have POE in them. The oil will be dark and non acidic with a burnt smell. The compressors are usually locked.
The oil and refrigerant are designed to be miscible, so by deisgn it's difficult to get the refrigerant out of the oil by vacuum. Hence, the relaxed requirement once there's refrigerant in the oil.

My understanding is that POE likes water even better than it likes refrigerant, and that once it's there, a vacuum pump WILL NOT get it out.

I've been looking for some kind of a vapor pressure or evacuation chart that includes POE (or even mineral oil) in the mix, rather than just water in a jar, but so far, I've struck out.

It's an extension for a thread here:
h{notspam}ttp://hvac-talk.com/vbb/showthread.php?p=3269622#post3269622