Coffin case

[270wsm]

Whats a good method for pinpointing a leak in a coffin case. My leak detector goes crazy anywhere in the case, even on low. I bubble checked the TEV and all visible fittings and welds. It has to be in the coil itself. But this coil is 12'. Is there a trick to finding leaks like this?

[cracker]

I Use a Weak Solution Of Soap bubbles....Not That Stuff You Bye In The Supply House.....To Thick....You Can Water It Down And use It......Then I Pump It Up To 400 Psi Of Nitrogen,......And Cover Every Thing.....Been Working For Me For Over 20 Years.

[icemeister]

A coffin case to me is a single deck frozen food or ice cream case. Is that what you have? Is the evaporator coil on the bottom of the tub?

If so, you may have a tube(s) on the bottom row that have been crushed and kinked by frequent ice buildup.

Solution? New coil. :(

Used coils are a possibility if you're willing to chance it.

[condenseddave]

Originally posted by cracker
I Use a Weak Solution Of Soap bubbles....Not That Stuff You Bye In The Supply House.....To Thick....You Can Water It Down And use It......Then I Pump It Up To 400 Psi Of Nitrogen,......And Cover Every Thing.....Been Working For Me For Over 20 Years.

I've never seen a coffin case coil that is tested past 150 psi.

At 400, you'll definitely find a leak... Might not be the original one, but you'll find one.

If the leak is in the coil, expose it, drive the evap pressure up and listen closely. If you have hot gas defrost, it'll be easier, but first, I'd find the puddle of oil that should be bear the leak.

If the coil as iced up recently, look at all the bottom passes, front and back, they tend to get crushed on the bottom, and open up where the tubing kinks inward, laterally on itself from the force of the ice building.

If it's a small leak, look at the tube sheets with some soap.

If it's a REAL strong hit on the LD, check the cases to the left and right, and the coil on the backside. Refrigerant travels down systems pretty fast.

[cracker]

How Many Evaps Have You Seen In Commerical Service Blow Up....The Factory Set The Stander For Coil Testing At 150...Not to Find Coil leaks....To Protect The Factory Workers From killing Them Self.

[rayr]

Those evaps aint no "L" copper, hell they aint even close to "M" copper.

[R12rules]

One in one hundred thousand would exceed the standard operating proceedure of testing an evaporator past one fifty PSIG!
Cracker, you have been fortunate nothing has occured that you have had to regret.

There are two reasons they print those labels telling how much pressure they test the coils under.... and one of them is NOT to keep the factory workers from killing themselves!


I believe the man is speaking of a self contained low boy freezer case, like a novelty case used in C-Stores.

Possibly the reason his LD is going off is the insulation in the case itself.

I have never had an evap leak in those cases.
I have had plenty of hi side leaks and also leaks in the coil of copper tubing behind the compressor which allows you to extract the unit for servicing.
Often these will leak slowly and not show up unless you are right on the spot.

Best to replace the whole copper affair with new, built in the field, and be done with it.
Providing that is where the leak is.

[condenseddave]

Originally posted by cracker
How Many Evaps Have You Seen In Commerical Service Blow Up....The Factory Set The Stander For Coil Testing At 150...Not to Find Coil leaks....To Protect The Factory Workers From killing Them Self.

Never saw one blow up.

I've seen about a half dozen develop stress leaks after some uneducated monkey doubled the test pressure during a leak test.

[market-tech]

Originally posted by condenseddave

Never saw one blow up.

I've seen about a half dozen develop stress leaks after some uneducated monkey doubled the test pressure during a leak test.



Hey condenseddave, Don't hold back, tell it like it is.

If it's been leaking for a while, or a significant leak, should be oil in the area. A little more info on the case (mfr, m/n) might help also. Increase the pressure on coil, hot gas defrost or close suction ball valve (assuming it's on a rack). Shouldn't be that tough to find. Soap bubbles work wonders! HTH.

[condenseddave]

You think that was too subtle???

[market-tech]

Well, maybe. I wasn't really sure about the point you were trying to get across!! <GRIN>