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Thread: Carbon Black
11-08-2007, 09:27 PM #1
Has anyone had to deal with carbon black attacking the silver soilder joints in a HVAC system. I am working in a tire plant and I have never seen the number of leaks i'm finding in this job site. Any help?
11-09-2007, 09:45 AM #2Professional Member*
- Join Date
- Aug 2006
- Vancouver , Canada
When you mention ' CARBON BLACK ' - what do you mean??
What kind of joints are leaking? Silfos?
I have worked in a Pulp and Paper Mill for the last 6 years - silfos joints take a kicking here as well, especially on the evaporator where it is wet.
I can't find the article right now, but a recent RSES Journal article spoke of airborne sulpher attacking the phosphorous in the silfos joints, essentially turning it to swiss cheese - what happens here is the joint weeps oil first, then progresses to a refrigerant leak later on. The only proper repair is to cut out the joint, replace it and then I paint it with Heresite or Glyptal.
Silver solder ( 45% braze ) or Sta-Brite seem unaffected.
Over the years in my experience, similar leaks occur in restaurants especially in coolers that they store acidic foods such as onions, pickles, tomatoes, some cheeses, etc. - coated coils are used - ususally some kind of phenolic coating. The worst I ever saw was a large dough retarder in a production bakery. Two new coils leaked like stink after 6 months. Apparently a byproduct of the yeast was the culprit.
At the mill here, all the major evaporator coils were Heresite coated from new, but new was 17 years ago, and the Heresite is breaking down, and replacement is the only option. As well lots of other joints are leaking as well - Heresite works well. The sulphur comes from the paper process and is airborne constantly. Any new equipment I specify now has Heresite or Phenolic coated evaporators, and stainless steel drain pans. I paint the exposed joints before putting it into service that are not done from the factory.
While not sure about the tire process, if sulphur is in it, that is likely the culprit.
Good luck.Superheat and subcooling tell it all !
11-10-2007, 08:26 PM #3
sounds just like my tire plant problem. I have been making my repairs with 0%silver soilder. Thanks
11-13-2007, 09:32 PM #4Professional Member
- Join Date
- Feb 2004
- Home is Azle Texas, work in Dallas-Fort Worth & surrounding areas.
Are You in Wilson ? I used to do work there at the Firestone plant. Tou have to start with clean joints & coat with Heresite spray. Eddie at C.C. Dickson used to get it for me. Best sucess was to REPLACE a joint & spray with Heresite. On the cabinet coolers, we used to take them apart & coat all joints before they were put into service. Hope this helps.
Don't choke choke on the price of the spray - also good for systems exposed to salt air/mist.
Goodluck.Life as an adult is much like life in kindergarten - If I make it through the day without crying or hitting some one, then it was a good day!
11-17-2007, 12:03 AM #5
Yep its Firestone, (remember me from AP Parts I been at Wilson for the past 6 yrs.) And Eddies gone from CCD
11-17-2007, 12:16 AM #6
What's Heresite, and where do you get it?
11-17-2007, 08:09 AM #7