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Old 12-27-2019
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max hendrix max hendrix is offline
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Join Date: Jun 2008
Location: Weatherford
Posts: 736

John, your statement is correct “if” you start with 5% in a tank. If you start pumping liquid in at “0-Zero” % then my statement is correct. It has to do with the fact that propane is stored and transported under pressure in a liquid form. And in the case of our RV’s we use it in gaseous form.

Vehicle tanks like the OP mentioned “forklift” use propane liquid. Therefore the tanks are built differently. They are not interchangeable and it would be extremely dangerous to burn liquid propane in a gas grill or other appliance. This is one reason why the industry now uses “modern” OPD valves. The valve float will shut off inflow when the tank reaches normal tank capacity. Old style valves did not do this and a careless person could overfill a tank resulting in extreme danger for the consumer who tried to light his burner when it was spewing liquid.

Although propane systems are different because of gaseous properties, I will use a 55 gallon barrel of diesel as an example. If you start to pump fuel out of the barrel without allowing air to enter, a vacuum will eventually cave the sides of the barrel in. Same thing happens if you fill a barrel without allowing air to be displaced. Pressure will eventually build up and cause fuel to shoot out onto your shoes. We’ve all done this when filling our tanks too fast at the truck stop.

I realize that is an extreme simplification of system dynamics.

I welcome your clarification of additional information

Max Hendrix
Weatherford Texas

96 BMC 40' Sold
2008 HaulMark Super C S&S
Freightliner Chassis w/ 515hp S60 & 12sp Ultrashift
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