Measure a pressure inside the tank of a cigarette lighter

[HilaryE]

Dear All,
Did you try to measure the pressure inside a cigarette lighter, a barbecue lighter or similar? I mean a gas-state fuel pressure in say half-full tank of a lighter. The typical valve of a lighter does not have a thread so we could firmly attach a pressure gauge.

The pressure of the gas-state fuel inside the tank's lighter should be its vapor pressure (at a certain ambient temperature). However, if we do not know what is the actual concentration of solvents (e.g. butane, propane, etc.) the pressure is unknown.

Thank you.
Regards

 

[3DDave]

The boiling points of propane and butane are sufficiently separated that there is unlikely to be enough propane in the typical butane fueled lighter to make a difference in practical use.

One could vent and capture the contents, add a tiny pressure sensor to the side with epoxy, and then refill the device.

 

[IRstuff]

The fill port would seem to be adaptable to a pressure gauge; most tire pressure gauges aren't threaded either

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[LittleInch]

Well I had a look at a can of lighter fluid in the shed just now and it says it is 100% butane, which I think is fairly standard.

This would give lower pressures than Propane so for small strange shapes like lighters I'm not surprised.

As the vapour boils off to create the pressure it matters not whether the lighter is 90%, 50% or 10% full - it will be the same pressure at the same temperature.

That's why aerosol manufacturers loved using propane as the propellant - constant pressure all the way to the end.

Care to tell us why you want to know??

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[HilaryE]

Hi Guys,

Thank you for your quick feedback.

@3DDave
The idea with epoxy glue is interesting. I will think about this option.


@IRstuff
Indeed, some tyre pressure gauges do not have a thread connection. Although, expected pressure inside a little tank (with an in-built cigarette lighter like-valve) with a mix of (among other things) butane, isobutane and propane can be in the range of 2-5 bars (depending on a fuel). I wondered whether it would be possible to make the connection leak-proof, at least for a moment, to read the actual pressure on a gauge display.
I will look for a suitable pressure gauge.

@LittleInch
In terms of the overall purpose of the fuel pressure measurement, I need to know the pressure to make some fuel flow calculations (pressure in the tank is an important input data).
Indeed, the cigarette lighter fuel is often described as the butane (e.g. on the can's label). I purchased a few cans of such fuel, and usually, I find (in online specifications of these fuels) that 'butane' is actually a mixture of butane, isobutane, propane, and a few other minor solvents. Butane is often a dominant solvent but the vapor pressure of propane is more than 4 times higher than butane. In some specifications of fuels, I find that that propane concentration can be in the range of 8/10% to 30%. In such a scenario, 20-30% of propane mixed with butane/isobutane means a considerable difference in vapor pressure (when compared to pure butane).

Thank you again.
Regards

 

[IRstuff]

Bicycle tire pressure can be up to 9 bar, with the same tire pressure gauges that have no screw threads

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[LittleInch]

Well if you don't know what your fuel is then it doesn't matter what the pressure is?

Try looking at this which will give you a low and high range depending on what you want to assume as your max propane content.

https://www.engineeringtoolbox.com/propane-butane-mix-d_1043.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MintJulep]

Are you actually trying to measure the pressure of a lighter?

Or is that just a "for example" analogy that you're using to make it more difficult to get useful help?