True crap

[angryk]

Has anyone run into a deteriorated liquid line on true freezers? I've encountered four of them in about a year's time. The liquid line is taped together with the suction in the loops of line set going from the condensing unit to the cabinet. The state of the l.l. looks like what a discharge line condensate evaporater loop lokks like after a while. When the line is bent, or pulled, as in pulling the condensing unit forward, it develops pin hole leaks. The leaks are very difficult to find, especially with r404a. I used to like true. Now I find myself not wanting to work on them.

[herefishy]

I've never encountered such a problem, and I service and sell a lot of True. Copper is Copper, right?

Is there something in common with the applications that manifest this failure? Like equipment located near a swimming pool (chlorine)?

[angryk]

No nothing in common, not even age. The first one i saw was r502. The one I found two weeks ago was r404 and only two years old. My boss thinks I am making it up. Maybe it's from sitting in the moisture contained under the insulation. Maybe it's inferior copper on that 3/16" line. Never had a problem with the suction. I would even hold onto the entire liquid line for a while as evidence for whoever doubted me. I don't know. I posted hoping somebody else could back me up, but I guess not.

[chemi-cool]

HI John.

It comes to me now that I`ve had some problems with copper tubes. I found out that the problem was a weak connection between the copper and the galvanised steel. It creates a bad electric coductivity and the copper works as anode and starts to deteriorate. the solution was to silver solder all the connections.
I have installed a new condenser. The type of refrigerant in the system has no importance. There is no oxygen in the copper tubes (I hope) so that explaiens why it happends only on the outer side of the tube.
Hope that helps.
Chemi

[Peter_1]

Am i wrong if i think that the galvanised part will start to erode (instead of the copper) because it is higher in ranking in conductivity list (i don't know the correct English translation for it, starting with gold on top of it and going to Zn)
That's the reason why they galvanise steel and the self-sacrifice anode in electrical heating boilers (again, yhe correct translation is difficult for me) ) so that the Zn starts to detoriate instead of steel or copper.

[chemi-cool]

Hi Daliti,
I will try to explain it better, as both of us are not English and my Dutch sucks.
During manufacture of coils, a high polished, hardened steel rod is being knocked into each copper tube and expands it to the size of the hole in the aluminium fins to achieve good thermal conductivity. If the hole in the galvanized steel is too big - problems will start. Another thing is that the steel rods are getting smaller in diameter at the end part which leave the galvanized stell sheet a bit loose. I am not sure exactly how do you call this process but the result is ALWAYS holes in copper tube.

Chemi

[Bones]

i have seen very bad pitting on liquid lines, causing leaks the size of a pinhole.... but this has only been on domestic's 15-20+ years old...

nothing of that sort on commerical fridge? as you are refering too...

[Stuart]

Hi Daliti,

I think this is what is known a dezincification and from the way I understand it you are just about on the money with your explaination.

[Mark]

hello angryk
what do they store in the freezer?I once came across a cheese/deli cabinet ,copper lines were perforated as well,the only logical reason was down to what they were storing in the cabinet.Never had this problem in a LT application though.?
regards mark

[chemi-cool]

Hi Mark,
I did a job some years ago to a creamery that dade goat cheese products/ franch smelly cheeses. They have changed the evaporator coil every six months!! I got them a stainless sreel one
and added an extract fan that works every 10 minuts for 20 seconds. I looked at the old evaporators and under the fins, the copper tube had many small holes and a lot of small caviteis.
I think the cheese releases some acidic gas which attaks the copper. You are right about not seeing it in LT application, there is no bacteria activity in LT, therefor no danger to copper tubes.

chemi

[Peter_1]

Same problem with fish (ammonia), evaporators in oak wood-drying equipment (tannic acid), salami, refigerators with a lot of salt in it (fishing boats and briny refr.), the entrails of animals foudn in slaughter-houses, ... in short, all environments which react chemically with copper.
Also the condensors nearby the sea.
For a supermerket chain, we always have to treat the coil with a Blygold coating.
At one specific client (poultry slaughtery), each time we change evaporators, we change it with a stainless-stell evaporator (Goedhart) and they are even not that expensive.
Any relation with R404a? Is the oil perhaps acid? Never ran into these specific problems wit R404a.
Peter