- #1
Jehannum
- 102
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- TL;DR Summary
- In UK LPG installations, propane is regulated to 37 mbar and butane to 28 mbar. Is my guess at the reason for this correct or is it just a coincidence?
It's desirable that propane and butane be interchangeable as fuels in gas-burning appliances. However, butane has a higher calorific value. If used at the same pressure as propane it would give a higher heat output.
My guess was that the reason propane is set to a higher pressure is to offset its lower calorific value (CV).
Numerically, if you multiply 28 mbar by the ratio of CVs of butane to propane (122 / 93) you get (near enough) 37 mbar.
This made sense at first but I later realized that these are gauge pressures. I might expect this simple ratio relationship to work on absolute pressures but not gauge pressures. So now I'm thinking it's just a coincidence.
I train people on this stuff, so I need to get it right. I would appreciate any input.
My guess was that the reason propane is set to a higher pressure is to offset its lower calorific value (CV).
Numerically, if you multiply 28 mbar by the ratio of CVs of butane to propane (122 / 93) you get (near enough) 37 mbar.
This made sense at first but I later realized that these are gauge pressures. I might expect this simple ratio relationship to work on absolute pressures but not gauge pressures. So now I'm thinking it's just a coincidence.
I train people on this stuff, so I need to get it right. I would appreciate any input.