View Full Version : brand of oil chages in nh3 systems

Shane Rupe
08-02-2003, 06:01 AM
Have any of you been through this.

Where I work they have changed oil brands several times in the past few years, just to save a few penneys.

They look at the price of a gal. of oil but dont look at what it does to the system ...............We end up changing oil filters about 5 times as often as we should have to and it seems to kill v-rings and 0-rings on our shaft seals..........not to mention the problems we have with coalesing filters.

If you are looking at changeing brands of oil to save a few bucks
I would say dont do it, stay with what is working good for you now.

08-02-2003, 09:48 AM
Hi:) Shane
Oils in NH3 systems is a bit of a problem. Polyalphaolafin oils (pao)
,probably not the correct spelling, are a great oil at low temp on NH3, but they have that nasty habit of shrinking your o-rings. I have been trialing an additive that swells the seals to compensate, it works well but the problem is it was sold to us by an oil manufacturer with agreement that we would start using their oils which are expensive but they do work well.
A pao oil is virtually a life time investment as in a properly installed system you only test the oil and change the oil filters, seldom having to change the oil. Why are you changing the oil so often:confused: does your company not TIG root the welds in their systems? or do they know best and just arc weld everything?
There is another oil commonly used with NH3 and R22 that is an alkabenzine, this doesnot degrade o-rings and in some cases actually will swell up o-rings, say if you are changing from mineral oil, the draw back is it doesnot pump like the poa at -40 in pump circ systems, then if your coalesant filters are working you should not have oil in your pump system lowside.
The secret may be in the original installation and it's cleanliness as much as the oil you are using, both the pao and ab oil will wash your system for you, if the jobs not TIG rooted forget using either of these oils as you will have a plant that will give trouble all it's working life.
Happy reading. Regards. Andy:D

08-03-2005, 01:44 AM
Changing oils so often is a waste of money and time if you have a well maintained and clean system. Even with the old mineral oils, we did not have an oil change interval. Monitor your oil and take oil samples at 3 month intervals. If the oil is in spec, leave it alone.

Now, are you adding a lot of oil? If you have a closed loop, you should be reclaiming the oil through an oil still (pot) or other means of recovery. If you are tossing the oil...why? Is the system dirty and your oil is contaminated?

Mixing oils from one vendor and oil from another vendor can spell trouble. They may have a slightly different additive package and react with each other. I have see two approved WF-68 oils mixed and cause a lot of foaming in a screw compressor system. The solution was to go back to one oil and flush the stem to get one oil in it. The oil vendors will generally tell you that you can mix oils. My experience is negative, especially in the ammonia systems.

The continued practice of changing manufactures is a money looser in the long run.