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'[OT] Intrinsic safety & Gasoline pumps [TECH non'
1999\10\12@163355 by Russell McMahon

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>And how to get "the smallest sparks"? We can have very small sparks even
>with very low voltages. To have a spark is necessary to have an electric
>field higher  that a determined value that depends on the material:
>dielectric rigidity .
>So, to have a very small spark in a gas with a small induced voltage is
>necessary to have a very small gap between two electrodes with a difference
>of potential.

I should have mentioned "intrinsically safe".
I'm not expert in the details but it is "known" that if you limit available
energy then you can produce an electrical situation where there is not
enough energy available for ignition.
Such equipment limits both maximum possible voltage and current inside the
safe area.
A web search for 'intrinsically safe" will turn up more than you ever wanted
to know on the subject.

Equipment in eg Petrol Pumps is either intrinsically safe OR operates in
mechanical containment which is guaranteed not to allow ingress of flammable
gas mixtures. I would have thought this would be an extremely difficult task
indeed, but as I have never seen a petrol pump dismantle itself explosively
and as the pump energy is well above intrinsically safe levels I guess this
means that they have got it down to a fine art.


     Russell McMahon

>From another world -

What can one man* do?
Help the hungry at no cost to yourself!

(* - or woman, child or internet enabled intelligent entity :-))

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