testing refrigerant for moisture???

[under pressure]

What methods do you prefer for testing for moisture in operating equipment when you start maintaining equipment at an unfamilure site?

Sight glass, oil sample, refrigerant sample, megger? looking for input, seems like there is always a new gadget that that shows up that does everything but butter your toast. just thought I'd ask, thanks............................................ .

[mikep]

We recover and reclaim refrigerant to ARI standards and use the Checkmate by Refrigeration Technologies I would highly recommend. Here is a link, there is also a video:
http://refrig.com/Product/Refrig_Oil_Test/Checkmate/checkmate.html

[flange]

if there is any question, united sells a kit to pull a liquid sample amd have it analyzed for a few bucks. The report tells you a lot.

[jpsmith1cm]

I guess it would depend on the size of the equipment how I handled concerns about moisture.

Small charge (10 pounds or so) I'd pull charge, change driers and oil if necessary, pull micron vacuum and recharge with virgin.

Middle sized unit (up to 100#) I'd be looking for indications in the sightglass, doing repeat drier changes. If absolutely necessary, pull charge and evacuate.

Larger equipment. Again, I'd be looking for indications in the sightglass. This equipment is more able to be cleaned up. Regular and consistent drier changes, oil changes. In this equipment, at least what I work on, removal of charge and micron level evacuation is not possible under normal circumstances.

[just_opinion]

I guess it would depend on the size of the equipment how I handled concerns about moisture.

Small charge (10 pounds or so) I'd pull charge, change driers and oil if necessary, pull micron vacuum and recharge with virgin.

Middle sized unit (up to 100#) I'd be looking for indications in the sightglass, doing repeat drier changes. If absolutely necessary, pull charge and evacuate.

Larger equipment. Again, I'd be looking for indications in the sightglass. This equipment is more able to be cleaned up. Regular and consistent drier changes, oil changes. In this equipment, at least what I work on, removal of charge and micron level evacuation is not possible under normal circumstances.

Why do we have to do all those hard and expensive works when we don't even know if there is any moisture in the system ???

The OP ask how to test for moisture in the system.

[Southern Mech]

I do 2 thing's.

1- I use the checkmate test kit, avail from RE Michels, works well. Used it for 14yrs in res and light comm.
2- I take oil samples on my bigger chillers and such that I get oil from easily and send them to a lab for a complete report.

[just_opinion]

What methods do you prefer for testing for moisture in operating equipment when you start maintaining equipment at an unfamilure site?

Sight glass, oil sample, refrigerant sample, megger? looking for input, seems like there is always a new gadget that that shows up that does everything but butter your toast. just thought I'd ask, thanks............................................ .

If you can isolate the freon, then you can use the T/P chart.

If there is sight glass, then you know what to do.

If you want, you can buy a kit, which detect moisture, and acid. It also recommend ways to clean up if detects

If the system contains small amount of freon, and the labor is extensive, then dump it and replace with new one.

Besides, how much moisture we are talking about ? If you concern the moisture entering the system by installing/removing gauges when do routine check-up (I think it is rediculous), then not worry.

But P/T chart is most economical.

[under pressure]

Thanks for all of the good input. I was involved in a discussion with a customer about a system with a bad plate and frame heat exchanger that failed and flooded one of the two refrigerant circuits. It was more of a currious question about early dectection of moisture in other equipment where the sight glasses were old and sunbleached so that the moisture indicators were questionable in color from what appears to be ultraviolet bleaching......................... I guess this supports that there is no substitute for good preventitive servicing of equipment. and when moisture indicators are no longer reliable it is time to replace them as you would any other critical device. Not to mention base line logging of meg readings on motors etc, so you can see changes from season to season............................thanks again.

[flange]

lok in the bulls eye of the compressor to see if you have oil or milk?

[RobY]

Thanks for all of the good input. I was involved in a discussion with a customer about a system with a bad plate and frame heat exchanger that failed and flooded one of the two refrigerant circuits. It was more of a currious question about early dectection of moisture in other equipment where the sight glasses were old and sunbleached so that the moisture indicators were questionable in color from what appears to be ultraviolet bleaching......................... I guess this supports that there is no substitute for good preventitive servicing of equipment. and when moisture indicators are no longer reliable it is time to replace them as you would any other critical device. Not to mention base line logging of meg readings on motors etc, so you can see changes from season to season............................thanks again.

It is common for some mechanical contractors to pull a refrigerant sample on a regular basis to find out what the quality of the refrigerant in the unit is. You can do things like trend the moisture levels to see if there may be a slow water leak present, so you can find out potential problems before the sight glass changes color (which may be too late to prevent a big repair job at an inconvenient time). You can also look at things like the level of oil in a flooded evaporator that may be screwing up heat transfer, or the amount of oil in circulation to see if the compressor is still tight. It can also look for refrigerant and/or oil decomposition products from a motor burn or lubrication failure prior to a compressor failure, and also give you information on R-400 series refrigerant fractionation.

One big benefit of lab testing for moisture is it can tell you how close to saturation the moisture level is, so you can get some idea whether to look for free water in the system after a tube leak. There are times we can see free water drops in the refrigerant sample, and that tells the contractor what they are up against during the repair.

Granted, the Checkmate tube can be useful as a field screening test for moisture, and I think it can work very well for moisture only. I have had conversations with the manufacturer of the Checkmate tube, and I think they are doing a good job with their product.

What you use for testing moisture depends on what you need to learn, and what you are willing to spend. Like was pointed out, no one would test refrigerant from a small system, and on a medium sized system it would take special circumstances to justify a lab test, so the Checkmate tube may be a good choice. Large systems are where the extra information from a lab test can pay big dividends.


Rob Yost
National Refrigerants