Don,
I don't know whether it is applicable to your application, but a
traditional method is to immerse the part to be tested in a hot fluid
(say 70°C) and observe for bubble streams. The choice of fluid is
difficult. It must have a low surface tension and low viscosity; it must
be stable with time at the chosen temperature; it must not evaporate; it
must not be reactive with anything on the assembly; it must not affect
the electrical properties; it must be easy to clean off; it must be
cheap; it must not pollute; it must be non-toxic and non-flammable; etc.
Unfortunately, this miracle liquid does not exist but there are some
which come quite close. These are perfluorocarbons. They fill these
functions bar two: they are polluting and they are damned expensive. In
this application, the expense part can be minimised by good housekeeping
and recovery of drag-out losses. Notwithstanding, there will be losses
due to evaporation and these products are amongst the most
global-warming substances known to man, about 10,000 times worse than
CO2. This means that 1 kg lost is equivalent to 10 tonnes of CO2 and 10
tonnes of CO2 may be produced by burning 16 tonnes of motor fuel, which
is equivalent to about 20,000 litres, sufficient to run a modern car
200,000 km, or more than the average lifetime of a car. See what I'm
getting at? Recover every milligram you can. That having been said, I
guess you may be in Deutschland and there may be regulations regarding
the use of PFCs in your country, either in force or proposed. Check
carefully.
Hope this helps.
Brian
"Steffen, Don E" wrote:
>
> 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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