Moisture In Evap Coil

[icesav]

Hi PPl,

Not posted in a while. Had alot of experiance in the past 18 months - working on a new project at work and this one has got me.

We have some split hermetic coolers to upgrade, we are replaceing the compressor all the 1/4 copper tube a new condensor but reusing the old evap coil. The evap coils are all differant ages but all bent in the same config. They are submerged in a water bath in which an ice bank is formed to a point until is cuts off next to a mechanical ice stat....

The situation at the moment is we have guys not willing to use the old coils that have compressor oil still left in them because they think it is detremental to the system, my argument is that oil is always circulated around a system with the refrigerant for lubrication. Some times the coils have water mixed with the oil because of leaks in the heat exchanger hence why we upgrade them to Air Cooled systems.

All I do is send the could into the steam room have them steamed internally until they are clear of oil and then put the evap coil on its own direct onto a vacuum pump and leave it to go down to 2000 microns or (2 Torr).

Will this remove all the moisture or will the vapour condensate inside the coil again as soon as I remove the vaccum ?

If the case is that it does not remove all the moisture what would be the best way to remove it ?


Your comment and suggestions are very welcome, Thank you

[Tesla]

Hi icesav
Your method will not work as moisture only starts to be removed below 1500 microns. You would need to (if evap only) vac down to around 350 microns then hold vac for 24 hours - if it doesn't go above say 450 microns then pressure test with nitro (+trace) as there are many different types of leaks: vacuum, pressure, temperature, vibration, micro and combination dependent leaks.
This would be for the evap only isolated from the system.
Tesla

[icesav]

Thank you for your input Tesla, however I think I should have been more clear. The systems we take these evap coils off of have leaks, comp faults, scrap etc.... We dont need to find leaks we just need to get the moisture out of the coil in the most effective way possible.


Thank you

[tonyelian]

hi
how much is the size of the condensing unit.if it is small you can seperate the condenser &fit a schreider from one side.with 11or 22 refrigerant take the can upside down to let the liquid enters &out from other side of coil

[cool runings]

Thank you for your input Tesla, however I think I should have been more clear. The systems we take these evap coils off of have leaks, comp faults, scrap etc.... We dont need to find leaks we just need to get the moisture out of the coil in the most effective way possible.


Thank you

What you are doing sounds fine.
Just make sure when you vac it is in a ambient temp of about 20 deg C and
then leave on vac for a full 24 hours or longer. the warmer the temp and the
deeper the vac will gaurentee that all the moisture is removed.

Good vac pumps will pump down to at least 400 microns ( 0.4 Torr).
2 torr is the minimum but lower is better.

Then do a standing test. Let the evap sit in vac and watch the torr gauge,
if it remains constant then you will have removed all the moisture, if it raises
then there is still moisture inside and the vac will need to be continued.

A tripple vac could be used if you have access to Oxygen Free Nitrogen (OFN)

Vac once then repressure with OFN, Vac again and repressure with OFN and finaly
vac to lowest possible.

Each vac will remove the moisture and each OFN repressure with act like a sponge,
absorbing moisture, that is then vented.

All the best

coolrunnings

.

[icesav]

That is very sound advice thank you very much. I know how even the smallest amount of moisture can go along way in a system. Worst case is the metering device become blocked

[Fri3Oil System]

Hi chaps,

we did a cleaning of water last week on a milk store where they had had a leak in the evaporator, getting water in the refrigeration system.

We got all water and oils out by the cleaning (flushing in a closed circuit) and then dried each circuit(total 3 circuits) with vac and OFN.
Repeating each vaccum and dry nitrogen operation 2 or 3 times per circuit. When you "break" the vacuum with OFN, you can put a paper at the exit of the N2, and check if it's wet, until the paper is dry. This way, you can get rid of the moisture. we didn't hold the vac for 24h btw.

Regards,

Nando.
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