Starhauler1@aol.com wrote:
> Hello Ed
> Yes of what you said is correct the triangle of fire. Fuel, Oxygen
> (Oxidizer) Ignition temp yep remember that from Damage Control School USN.
> Another reason that propane tanks are purged is to insure that there is no
> moisture in the tank, for corrosion and to prevent icing. Icing happens to
> propane customers our cure is to inject methanol into the tank to absorb the
> moisture.
Interesting. Clearly, when the propane goes from liquid to gas, it cools a lot,
and any moisture could freeze up the valve or regulator.
> Would also like to point out that gasoline does not burn as a
> liquid but it is the fumes that burn.
Correct.
> Gasoline chilled below its flash point
> can put out a lit match.
That's true of any liquid, gasoline, acetone, anything.
> Diesel though can ignite under compression hince no
> spark plugs
In a Diesel engine, it is the air/fuel mixture being heated by what is called
"adiabatic compression" (compression without heat transfer) that raises the
mixture to the point it ignites.
> but the flash point of diesel is no where close to gasoline.
I know you can run a compression ignition engine on gasoline. That is what
"knocking" is, pre-ignition due to compression. An octane rating is, after all,
a rating of how much you can compress the mixture, before it compression
ignites. Higher compression engines require higher octane fuel.
> Interesting though is propane boils at-44 the boiling happens when the
> pressure in the tank is reduced by the furnace for example the liquid propane
> then turns to gas which increases the pressure to an equal basis and it
> happen over and over again.
Within a tank, there is an equilibrium ( a balance) between the liquid and gas.
In a closed tank, the gas pressure increases until the vapor pressure of the
liquid is equal to the gas pressure. If the tank is heated, the vapor pressure
goes up, and then the gas pressure must rise to keep the equilibrium. This is
why propane tanks have pressure relief valves, so that the tank does not rupture
when left in the trunk of a car, in the sun.
> One of the reasons for a propane tanks design is
> for the surface for the boiling action.
If you are withdrawing gas from a tank containing liquid and gas, the liquid
boils in the tank to maintain equiliblium (see above). This boiling requires
heat. That heat comes through the tank walls. If there is insufficient heat that
way, the liquid in the tank will cool down, just like the evaporating water in a
swamp cooler, and the tank pressure will drop, eventually to the point no more
gas comes out.
The squat shape of the propane tanks allows a large surface area for boiling of
the liquid and lessens the spurting and splashing of the liquid, so liquid
propane does not get into the outlet and cause surging or uneven operation.
> Example a propane torch can hardly
> burn at-30 tried it in Ohio one time darn cold but the surface area does not
> come close to a 500gallon tank hooked to the house.
There is a lot of stored heat in the liquid in a 500 gallon propane tank. With
reasonable withdrawal rates, it won't chill down much, and so the gas will keep
coming.
Do you know if they bury propane tanks in the far north, where it gets REALLY
cold? Maybe they have tank heaters?
> Hauled propane and
> installed.
> Billy P. Whyde
> M-817, M-103 Owner in Ohio
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