How can I find the source of a leak in a vacuum oven?

Question

At my plant we use a vacuum process to waterproof parts.  One of our vacuum ovens has some sort of a slow leak and will not maintain a vacuum.  Myself and my production manager have gone over the oven several times and cannot find the source of the leak.

Can anybody give me some tips on how to locate the source of a vacuum leak?

Brian T · Accepted Answer

Vacuum ovens are low vacuum items. Rarely under 1 micron. Put the oven under a good vacuum and use a squirt bottle with acetone in it to spot the leak. 
Start with ports with the vac. line and go to the ports with the gages. If that doesn't indicate a sharp reduction in vacuum when sprayed with the acetone, go to spraying all along the seal areas. If that doesn;t show the leak, you have a structural crack in the oven. Varian makes a one part vacuum epoxy that is good to a fairly high temperature. Paint it on all surfaces and port connection areas and wait for it to dry.

jpopelish · Answer

If you can slightly pressurize the oven (with the output of a vacuum cleaner, for instance) you might find the leak with soapy water applied all around the gasket edges and other pipe joints.  Look for bubbles.

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Regards,

John Popelish

How can I find the source of a leak in a vacuum oven?

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