Measuring Propane Levels

How do you judge how much gas is left in a propane tank?

How do you judge how much gas is left in a propane tank?

We tested two simple methods for measuring the level of propane in a tank. First we rapped on the side of the tank, noting the sound it made as we progressed from the top to the bottom. Full tanks resound with a solid thump; empty tanks echo. The point where the sound switches from an echo to a thump indicates the level of the fuel. This method is passable but inexact.

Next, we poured hot water down the side of a tank and noted the tank’s temperature in different spots. The empty portion of the tank was warm to the touch, while the full portion of the tank stayed cool. Here’s why: Under pressure (as in a propane tank), propane is both a liquid and a gas. The liquid portion sits at the bottom of the tank, and the gas portion is at the top. Hot water poured over the side of the tank will stay hot when it meets the top portion of the tank, making the tank feel warm, because the gas does not conduct heat well. The liquid in the bottom, meanwhile, will conduct heat away from the side of the tank, making it cool to the touch. This method was surprisingly accurate.

THE BOTTOM LINE  Use the hot-water test to estimate your tank's propane level.


This is a members' feature.