What is pressure of natural gas and LP or “liquid petroleum” gas inside the gas tank?
There is some confusion, even among LP gas service technicians about just what is the pressure inside the gas containers they deliver to or fill at properties. Perhaps this is because the gas laws (see Boyle’s Law discussed at this website, for example), explain that the vapor pressure of LP-gases varies as a function of temperature. “Vapor pressure” is the force exerted by a gas, LP gas in this case, attempting to escape from a container (say by pressing on the container’s interior surfaces, or exiting at a gas valve if the gas valve is opened and not regulated). Some typical vapor pressures of LP gas (propane) are given just below. These pressures vary in real life depending on the purity of the gas and the percentage mixture of propane and butane. Butane is generally going to show a much lower vapor pressure in the container than propane. But you can see from the table that as outdoor temperature varies between zero and 80 deg.F., the pressure of LP gas in the outdoor tank varies wi
