RE: Vacuum Leak Detection

[Robert Myers <rmyers@inetone.net>]

>Despite the fact that I don't understand how the propane ingression
>would increase the engine revs, 

The propane or butane or ether is drawn into the induction system and burns
inside the cylinder as added fuel - hence the engine speeds up.  This is a
perfectly valid test.

>what I do understand is that you
>wouldn't worry about the vacuum leak from the comfort of your hospital
>bed. Propane/butane vapor in the presence of such a potential source of
>ignition is foolhardy in the extreme. (And yes, I am speaking from
>experience as a commercial hot air balloon pilot who has to attend
>regular LPG fire training)

Malcolm, the quantity of gas here is minimal.  The recommendation is to
work outdoors with a breeze so that unburned gas is swept away in the wind
rather than allowed to accumulate inside the engine compartment.  The
risks, even if ignition does occur, are minimal.  We are not talking about
50 gallons of propane from a ruptured LPG tank.  We're talking something on
the order of small jet of gas from a small butane/propane soldering torch.
A small puff of flame *might* happen in the ignition system is arcing but,
if so, it will be a small and *very* brief flame.

Did you ever, as a youth, pass your finger through a candle flame?  You
didn't get burned because the exposure time was so brief.  The same
principle applies here.

And I am speaking from experience as 8 years as a captain of a volunteer
fire department who has taught LPG fire training classes and 36 years
experience as a PhD organic chemist who has used flames as an everyday tool.


___
   Bob
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