We do something similar to what Bill is describing. We have an aluminum
enclosure that contains 4 disk drives. It is a hermetic sealed enclosure
(airborne application - apparently disk drives stop functioning around
15,000 feet in an unpressurized environment.) To check that the box is not
leaking around the covers or connectors, we pressurized the box to 4 psi and
immerse it to look for air bubbles. We do not use water, however. If water
got into the box it would ruin the drives. We immerse it in Fluorinert which
will not affect electronics should it leak into the box. In fact, we perform
pre-potting tests on high voltage power supplies while they are immersed in
Fluorinert to prevent arcing. Yes, Fluorinert is expensive (about $1,400 for
a 3 gallon container), but if you need a benign fluid to test in I don't
know of any other alternatives. (The MSDS says this material can be ingested
without any need for first aid!! Not sure what it tastes like though.) We
had a ss sink with a lid fabricated just a bit larger than the box and I
have only gone through one 3 gallon container in a year. Your mileage may
vary depending on the size of your box. Most of the losses are through drag
out.
Bob
Robert Barr
Manufacturing Engineering
Formation, Inc.
Voice: 856-234-5020 x3035
Fax: 856-234-6679
email: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Campbell, William
(wcampbel)
Sent: Friday, February 16, 2001 10:59 AM
To: [log in to unmask]
Subject: Re: [TN] Method of Leak Testing
You might try pressurizing your enclosure slightly with shop air (maybe 2
psi or so) and dunking under water- the stream of bubbles out tell quite a
story. Definitely not the best way, as the pressure applied here is
opposite real life in most situations, but good for troubleshooting, and you
won't get water inside. Good luck, and think of a good story for the
dishpan hands.
-----Original Message-----
From: Steffen, Don E [mailto:[log in to unmask]]
Sent: Thursday, February 15, 2001 8:34 PM
To: [log in to unmask]
Subject: [TN] Method of Leak Testing
Technetters
I am a Quality Engineer on a Safety Product that has a Leak Test
requirement. We are using a die cast aluminum housing that has a porosity
issue. I want to find out if there are any one in the TECH NET world that
might have some experience in leak detection methods. Water is out of the
picture. Because of the vertura effect, water can be sucked into a housing.
I am presently using water for troubleshooting purposes, but everything that
is applied to water is scrap. I have tried Helium gas but this is not always
reliable and repeatable. Is there anyone out there that can help me out in
this dilemma?
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