Evaporator leaks

[Pykester1]

Hello everyone.
I have a site with a multideck dairy cabinet which seems to have a regular leakage problem. It is running on 22 and every couple of months we are called in because the unit has lost most of its charge. Each time, the leaks are found at the return bends on the evaporator in the cabinet. The copper appears to blister and causes a small pin hole. We repair the leak with copper braze and charge the system and a couple of months later the same thing happens again. The system runs perfectly well when it isn't short of charge and other than this has never given any problems.
The cabinet is an Arneg Nimes 3750.
If anyone has any ideas what the problem might be and a possible solution, they would be gratefully received.
Thanks.

[nike123]

It could be some corrosion on copper pipes caused by atmosphere around these pipes.

Tinned iron, copper, galvanized iron, iron, and zinc.
With the exception of properly tinned iron, this group is unfit for use in contact with milk products. Tinned iron is equally so whenever iron is exposed.
http://jds.fass.org/cgi/content/abstract/12/2/140

[al]

Nike

Would this rule out most of the evaporators fitted to dairy cabinets i wonder, i know they're not in close contact but could continous spillage explain the leakage rates??

Great article by the way.

al

[nike123]

Nike

Would this rule out most of the evaporators fitted to dairy cabinets i wonder, i know they're not in close contact but could continous spillage explain the leakage rates??

Great article by the way.

al

Probably yes. I think that best way to fit proper evaporator is by consulting Alfa-Laval experts.
I am not familiar with diary products cooling. When I am unsure or unfamiliar with application, I always call local Alfa-Laval representative and they usually give me advice in few hours.

[CONROD]

Could be moisture in sysytem, R22 is known to carry moisture. Moisture freezes on the evap return bends, which are very thin and causes the blisters. I'd recover the 22, change the liquid drier, check the LP cut out on pump down and re-charge with a drop in to re-place the R22.

[tony--1]

Could be moisture in sysytem, R22 is known to carry moisture. Moisture freezes on the evap return bends, which are very thin and causes the blisters. I'd recover the 22, change the liquid drier, check the LP cut out on pump down and re-charge with a drop in to re-place the R22.


You got it spot on there get the gas out and get a good vac on system .if it s got defrost heaters get them on to heat up the coil.then recharge with gas jobs a goodin :D

[Latte]

The trouble is with these once its starts going it wont be long before the rest go. Now for the fun part, to replace the evap on these is a total pain in the ####

I assume it is the twin evap type (One evap above the other) which is located on the back wall of the unit so EVERYTHING has to come out including the shelf pillars to strip the unit to a complete shell.

Assume the unit is in a convenience store so has probably had dairy in it (milk/cheese) which will rot the evap when spilt

Changed one of these evaps only last week. If all goes well, 2 men x 6 hours should cover it, if it goes badly its probably nearer 8 hours each. Thats a heavy old evap to get in/out

Regards

Latte

[Pykester1]

Could be moisture in sysytem, R22 is known to carry moisture. Moisture freezes on the evap return bends, which are very thin and causes the blisters. I'd recover the 22, change the liquid drier, check the LP cut out on pump down and re-charge with a drop in to re-place the R22.
Hello Conrod. Thanks for your advice. This is what I had suspected, I just wanted it confirmed.
Cheers.
Pykester1

[Pykester1]

Thanks for all your suggestions.