Smoke machines

Paul Harrison <paulehar [at] netvigator__com> writes

>Has anyone tried putting a stage/disco smoke generator in a display
>case? I want to see how much some cases leak and from where, but I
>wondered about the residue left behind by the machines.

As an alternative to Smoke or CO2 machines for testing case
integrity I would suggest the following technique we employed when
testing for leaks in high vacuum heat treating furnaces (in a past
life as an engineer).

Create a positive pressure within the case:  for a small case this
can be done with a wet/dry vacuum that blows air out, or even a
small tank of helium. *Caution:  Do not over pressurize*, this can
be assured by temporarily installing a pressure relief valve of the
appropriate setting (although if you're using the wet/dry vac I
doubt there would be a pressure problem)

Fill a plastic bottle (with a pouring spout of some type) with water
and a bit of liquid dish washing detergent (experiment with the
mixture, what you want to end up with is a mixture that allows you
to blow bubbles like the popular child's toy we're so familiar with)

Slowly pour the mixture over all the seams and joins on the OUTSIDE
of the case looking for a bubbling action.  If bubbles occur you
have a leak at the point of bubbling, if not the joint/seam is fine.

This technique has the distinct advantage of not having to fill the
*inside* of the case with anything other than simple old air, or
whatever gas you choose to use.

Hope this helps,

Anthony Ayers


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                  Conservation DistList Instance 16:15
                 Distributed: Thursday, August 29, 2002
                       Message Id: cdl-16-15-003
                                  ***