Trane RTAC and oil samples

[JEF1980]

Anyone ever experence high moisture content in oil samples from 134a systems. Samples have been taken on machines that have not ever been opened up from factory. Second question why does Trane not put driers in there RTAC chillers any ideas.

[B1978]

So my RTAC 250 drier shell is a strainer only? How old is that RTAC?

[jayguy]

...Second question why does Trane not put driers in there RTAC chillers any ideas.

I know that they do put driers in there...maybe they have been opened up.

[JEF1980]

I'm going to take samples agian in glass sample botttles. Maybe POE is picking up moisture through the plastic bottles. We are positive that it has never been opened up. Does anyone know the reason for no driers are they thinking that the oil is so hydroscopic that it would pull mositure if there is any from driers anyways so no point in putting them in. Just thinking.

[JEF1980]

@ B1978 yeah they are a paper element everyone i've seen are like this.

[Screwit]

What moisture content are you seeing and more importantly what is the TAN?

The attached will answer you questions concerning the use of drier cores.

[Nuclrchiller]

Interesting document, Screwit. Thanks for sharing. I'm curious, where did you get that?

[Phisher]

POE oil moisture removal.pdf

[Screwit]

Interesting document, Screwit. Thanks for sharing. I'm curious, where did you get that?

No problems Nuclrchiller, came out of Europe at the time of the RTAC/ RTAD/RTWB release.

[Nuclrchiller]

No problems Nuclrchiller, came out of Europe at the time of the RTAC/ RTAD/RTWB release.

I was still at Trane at the time, but I don't recall ever seeing that over here. That explanation is simple and to the point, the way I like it.

[JEF1980]

Thank you

[FixItRight]

There is not much need for a oil sample in a air cooled screw with POE oil. You are only looking for acid in the oil and yes the POE does pick up moisture through the plastic bottles. It is better to just do a acid test.

[jayguy]

There is not much need for a oil sample in a air cooled screw with POE oil. You are only looking for acid in the oil and yes the POE does pick up moisture through the plastic bottles. It is better to just do a acid test.

oil samples do more than just look for acid or moisture. they also look for wear metals. as for the acid test, that is a Pass/Fail type of test. an oil sample will show you the acid level and over time, you can watch it rise and make decisions before it 'fails'.

[FixItRight]

Yes oil samples do more but a in screw there is no need to look for metal wear like you need in a centrifugal. Also any acid is bad and needs to be fixed asap. A oil sample on a RTAC is a waste of time and money especially if you use a plastic bottle.

[jayguy]

Yes oil samples do more but a in screw there is no need to look for metal wear like you need in a centrifugal. Also any acid is bad and needs to be fixed asap. A oil sample on a RTAC is a waste of time and money especially if you use a plastic bottle.

why wouldn't you need to look for wear metals in a screw? it is a mechanical piece of equipment just like a recip, scroll or centrifugal. as for the acid, 'any' is not a number that can be trended over time...sure, lower is better but what is lower? i have sampled many RTAC's (among others like it) using plastic bottles and found that the moisture pull through is not significant if you ship it within a day or two.

[Healey Nut]

Oil samples from high pressure chilers are pointless . The machine sits at a positive pressure , its not like a centravac where if it has leaks air gets in and moisture which create acids .The only reason for acids to develop in high pressure chillers is bad service practices and equipment failures (burnouts).
Also the oil charge (particularly on Tranes) is critical they are cut to the bone for unit efficiency .
So if you take half a dozen oil samples you have significantly reduced the oil charge .
Ok so add some more oil you say (you just diluted your readings and risked letting in moisture ) see my point ?
If you insist on taking them they should either be in glass bottles or shipped within 24hrs .
The only time I would take an oil sample from a high pressure machine would be . If the customer insisted it be taken, if the chiller suffered some kind of failure or if we took over another machine from another contractor where the chiller had had problems and refrigerant removal etc .
If you take an oil sample lets say for the sake of argument out of a 200ton screw machine . it comes back with elevated metals . Do you really and honestly believe the customer will say .Ok open it up and fix it , or sure I know its running well but slap a new 25K compressor on it anyway just to be safe ???? Lets get real here!!
Penny to a pinch of S%$# there going to say "when it croaks we'll fix it or buy a new one ".
Now I know your all going to say well we covered our ass and told the customer it was an issue so they cant come back at you . And to a point your right , but do you also think if you didnt take a sample and it croaked the story would be any different ?JMHO

[Tech Rob]

Oil samples from high pressure chilers are pointless . The machine sits at a positive pressure , its not like a centravac where if it has leaks air gets in and moisture which create acids .The only reason for acids to develop in high pressure chillers is bad service practices and equipment failures (burnouts).
Also the oil charge (particularly on Tranes) is critical they are cut to the bone for unit efficiency .
So if you take half a dozen oil samples you have significantly reduced the oil charge .
Ok so add some more oil you say (you just diluted your readings and risked letting in moisture ) see my point ?
If you insist on taking them they should either be in glass bottles or shipped within 24hrs .
The only time I would take an oil sample from a high pressure machine would be . If the customer insisted it be taken, if the chiller suffered some kind of failure or if we took over another machine from another contractor where the chiller had had problems and refrigerant removal etc .
If you take an oil sample lets say for the sake of argument out of a 200ton screw machine . it comes back with elevated metals . Do you really and honestly believe the customer will say .Ok open it up and fix it , or sure I know its running well but slap a new 25K compressor on it anyway just to be safe ???? Lets get real here!!
Penny to a pinch of S%$# there going to say "when it croaks we'll fix it or buy a new one ".
Now I know your all going to say well we covered our ass and told the customer it was an issue so they cant come back at you . And to a point your right , but do you also think if you didnt take a sample and it croaked the story would be any different ?JMHO

I'm with Healey and FixIt here. Oil analysis on a P.M. basis for air cooled screw compressors that are more or less disposable is a waste of time. The info you get from an oil analysis can be useful in the event that you suspect a problem. With POE oils, there's a high risk of moisture contamination before it even reaches the lab unless you use a glass sample bottle. We stopped doing regular oil samples on air cooled machines a while ago and opted to go with a simple acid test.

[jayguy]

i recommend oil samples on everything except scrolls...they are vaulable on scrolls, but like graham said, after a few oil samples, you have to add oil and then start the trending over because it is diluted...they really hold only a little bit of oil although they are getting bigger and the bigger tandem units hold more than their screw counter parts...so I may change my stance on scrolls in the near future.

the oil analysis provides too much information for so little a cost to ingnore in my opinion.

[Screwit]

i recommend oil samples on everything except scrolls...they are vaulable on scrolls, but like graham said, after a few oil samples, you have to add oil and then start the trending over because it is diluted...they really hold only a little bit of oil although they are getting bigger and the bigger tandem units hold more than their screw counter parts...so I may change my stance on scrolls in the near future.

the oil analysis provides too much information for so little a cost to ingnore in my opinion.

Same recomendations from down here, reckon it is in the customers interest to be proactive not reactive with maintenance.

For Trane products we were air-freighting plastic bottle POE oil samples into Charlotte and had no major issues with moisture.

[TheChillerMan]

The only time we take an oil sample from a screw chiller is when we do an R'Newal. It is required by the factory. They also want a refrigerant sample.