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Originally Posted by jayguy

i'm done....maybe.

Yep, me too. I will say though, whether or not I learn something, or whether or not I agree, as usual this type of discussion has given me food for thought. Thanks, to all.

Originally Posted by Nuclrchiller

Jay, I'm just gonna presume you're being facetious asking those questions. I just want to make sure this doesn't sink into some kind of argument. I think this is one of those things that are best left to a judgement call made on site on each individual piece of equipment, and application. Of course, keeping in mind such things as what has customer bought? What is customer expecting? etc... But I am curious - have you, or anyone, replaced a functioning compressor on a RTAC based on oil sample results? What about based on megger results?

of course i am being over-dramatic. the point that i am trying to make is why do anything if we are just going to wait until it fails? do you test oil pressure differentials on a recip? if it is close to the trip point but not tripping would you not try to stop it from catastrophically failing? have i replaced a compressor based on an oil sample result? not yet. but I have diagnosed problems and repaired them before failure based on oil sample tests...high copper content was a semi-recent issue. I haven't changed out a functioning compressor due to megger results, but I have investigated and remedied issues on compressors in the past.

i have no problem with making a judgement call (whether to take an oil sample or not) based on the customer and the application. it just seems that some people are making a judgement call on ALL high pressure screws with R134a from their living room. i'm done....maybe.

Originally Posted by FixItRight

why lube a motor? That is funny if you think that an oil sample is as important as lubing a motor. If you don't lube a motor it will fail but a oil sample is just a test. Also there is a high chance of contamination from moisture with POE.

He was being kinda broad using the word "chiller" since some motors can be lubricated.

Jay, I'm just gonna presume you're being facetious asking those questions. I just want to make sure this doesn't sink into some kind of argument. I think this is one of those things that are best left to a judgement call made on site on each individual piece of equipment, and application. Of course, keeping in mind such things as what has customer bought? What is customer expecting? etc... But I am curious - have you, or anyone, replaced a functioning compressor on a RTAC based on oil sample results? What about based on megger results?

Originally Posted by jayguy

lots can be done with the information. why log a chiller? why meg a chiller? why lube a motor? should we wait until all parts break before we fix anything?

i prefer to view myself as the waiter in a restaraunt...i am not to decide how the customer spends his money, but i know they won't do anything if it isn't on the menu. perhaps you are leaving some money (and profitable work) on the table.

why lube a motor? That is funny if you think that an oil sample is as important as lubing a motor. If you don't lube a motor it will fail but a oil sample is just a test. Also there is a high chance of contamination from moisture with POE.

Originally Posted by Nuclrchiller

True. But, as Healey Nut said, just what can (or will) be done with that information? If there is no backup chiller, AND it is a critical application, AND the customer says he would spend the money, based on oil sample results, then I can see taking oil samples. I have yet to come across a site, with RTAC's, that meets those conditions. I would be very surprised to see a customer actually spend that kind of money based on a test, while the chiller is still running.

lots can be done with the information. why log a chiller? why meg a chiller? why lube a motor? should we wait until all parts break before we fix anything?

i prefer to view myself as the waiter in a restaraunt...i am not to decide how the customer spends his money, but i know they won't do anything if it isn't on the menu. perhaps you are leaving some money (and profitable work) on the table.

any megger reading history on that chiller especially after a cycle

Maybe start budgeting for a future failure.

Originally Posted by jayguy

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

True. But, as Healey Nut said, just what can (or will) be done with that information? If there is no backup chiller, AND it is a critical application, AND the customer says he would spend the money, based on oil sample results, then I can see taking oil samples. I have yet to come across a site, with RTAC's, that meets those conditions. I would be very surprised to see a customer actually spend that kind of money based on a test, while the chiller is still running.

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.

Originally Posted by 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.

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.

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.

Originally Posted by 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

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.

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

Originally Posted by 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.

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.

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.

Originally Posted by 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.

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'.

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.

Thank you

Originally Posted by Screwit

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.