> Vapor pressure at 86 deg F:
> 
> Propane - 166 psi
> Butane - 41 psi
> 
> Construction of typical camping gas cylinders suggest contents is
> primarily Butane, with a skoche of Propane to keep some positive
> pressure in the cylinder at or near freezing temps.
> 
> Propane tank safety valves are designed to vent at circa 300 psi, IIRC.
> 
> 800 psi seems unlikely. Hope this helps.

It does, thanks. The 800psi was suggested by the person I'm helping
and he hasn't done too much technical research. I suggested back
that he take a canister to a gas supplier (eg BOC or Air Liquide) and
see if they can measure the pressure

The low temperature pressure is of interest as the product will be working
in any outdoor climate. I mentioned Paslode brand nail guns. They've
introduced a smart metering system for their nail guns, as until now their
guns are not reliable in cold conditions. I've seen the module which can
be retro-fitted but unfortunately it's encased in epoxy. It doesn't appear
to measure gas pressure, likely just temperature, and presumably there's
a micro with a look-up table based on gas laws to set the valve open time

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