Re: Inert Gas In Fuel Tanks

From:         Bob Falkiner <>
Organization: RJF Home
Date:         03 Nov 96 19:57:03 
References:   1 2 3 4
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bob mackey wrote:
> On 03 Sep 96 01:16:54 , Bob Falkiner <> wrote:
> >Mikeit takes only a small percentage of an inert gas to render an
> >explosive atmosphere "safe" regardless of what the gas is.

> The explosive limits of a fuel-air mixture vary widely depending on
> the fuel, the pressure, and the temperature. As Bob F. suggests, the
> key is whether there is enough heat output from combustion, to sustain
> a temperature rise that can continue the combustion. But it is not
> generally true that a few percent of exhaust gas will suspress
> combustion ...

> Two extreme fuel examples are hydrogen and acetylene. With either of
> these gases, adding 90% exhaust to a fuel-air mixture will leave the
> mixture explosive.

hydrogen and acetylene are *extreme* examples.....

hydrogen and acetylene are "anomalies" in that the explosive ranges are
so wide, and your example assumes that the water of combustion of the
diluent gas is fully condensed which is not the case under typical use
quoted.  Flue gas is mostly water so your basis is important!

if you take a more normal example of say butane, given a stoicheometric
mixture which is worst case, it takes by my info available less than 20%
of any "inert" gas to render the mixture non combustable.