evaporator leakage problem

May 16, 2010 11:02 PM

i have an aluminium tube evaporator with a fault, and want to use a vision or test system to find the fault. any good ideas? realistic ones..

in a production environment we are getting bad internal brazing. the brazing means that there are gaps in the top tank. the refrigerant will take a least resistive path, and performance falls away.
so i want to, for example, x ray the parts and find the bad braze. or use some leakage testing system to finnd the reduced flow path. i have tried to test bad parts with nitrogen, but because of the lack of density the problem of low pressure drop doesnt show up. any tricky ideas? sorry the info isnt too clear.

posted by edtut to Science & Nature (7 answers total)

Here's a page on different methods of refrigerant leakage testing for industrial applications - for most of them, you'd need refrigerant at full pressure rather than nitrogen. Best bet seems to be the electronic tester, tho your application may preclude it if it involves alcohol or C0 nearby. All of them seem like a better idea than x-raying all of the brazing - find the leak, then redo the braze or just duct-tape the mofo.
posted by Slap*Happy at 5:25 AM on May 17, 2010

I know nothing about evaporators, so my suggestions will be charmingly free from preconceived notions. That being said, the old way to find leaks in bicycle tires was to immerse them in water and look for bubbles. Is a similar technique possible here?
posted by Joe in Australia at 6:08 AM on May 17, 2010

I routinely use a smoke machine for leak detection. Not a party smoke machine, a diagnostic tester. Something more like this. I just recently used it to find leaks in an automotive air conditioning system.
posted by Jon-o at 7:03 AM on May 17, 2010

It also occurred to me that you could use a non-contact thermometer to find the leak. As you know, refrigerant temperature and pressure are closely related and the refrigerant temperature is going to plummet at the source of the leak as it equalizes with atmospheric pressure.
posted by Jon-o at 11:57 AM on May 17, 2010

Can you PT it?
posted by ctmf at 4:32 PM on May 17, 2010

Please note that the OP is talking about leaks inside a sealed enclosure. NOT leaks from inside the enclosure to air.

You might slice an evaporator open to see how the internal brazing looks. Band saw with small-tooth metal-cutting blade?
posted by exphysicist345 at 11:09 PM on May 17, 2010

Response by poster: thanks for the answers. unfortunately, as ex says, the leak is internal. i didnt manage to find an appropriate method, thats the way it goes sometimes.
posted by edtut at 11:09 PM on July 14, 2010