Propane Lost in a Leak - How Many Gallons did I lose?

A common question propane dealers have when customers have a leak is "how much gas did I lose?". The answer is usually not that much. In reality, a small leak on a tank will result in the loss of a maybe a gallon of propane over a considerable period of time. However, all questions about leaks should be directed to your propane company. This page is only concerned with the amount of propane that may be lost as a result of a leak. Also see Checking For Propane Gas Leaks

Propane Leaks and Gallons Lost

Consumers often feel that a leak on their propane tank results in the loss of many gallons of propane gas. The following examples will hopefully illustrate that the actual amount of gas lost is nowhere near what they envisioned. We've all seen a helium tank fill balloons and we're all familiar with the loud hissing noise and force at which the helium is coming out of the tank and into the balloon. If you hear a propane leak that's remotely similar to that of a helium tank filling a balloon, you need to be calling the fire department instead of reading this! We'll now use that which we're familiar with and attempt to equate it with gallons realistically lost in a propane leak.

Propane Leaks - Gallons and Cubic Feet

First it's important to understand that one gallon of liquid propane will produce a little over 36 cubic feet of vapor. So when understanding the relationship between propane liquid and vapor, it's important to know the volume comparisons between the two. One gallon of liquid propane occupies .13 cubic feet of space. But when the liquid propane boils, the propane vapor produced is equal to 36.39 cubic feet. Propane gallons to cubic feet of vapor conversions are as follows:

• 1 Gallon of liquid propane produces 36.39 cubic feet of vapor 
• 5 Gallons of liquid propane produces 182 cubic feet of vapor
• 10 Gallons of liquid propane produces 363.9 cubic feet of vapor
• 25 Gallons of liquid propane produces 910 cubic feet of vapor
• 50 Gallons of liquid propane produces 1820 cubic feet of vapor

For further reference when investigating the actual amount of gas lost in a leak, let's look at propane tank dimensions and the cubic feet measurements inside common propane tanks found in the US:

• A 5 Gallon Cylinder has .65 cubic feet of interior space
• 150 Gallon Tank has 20 cubic feet of interior space
• 250 Gallon Tank has 33.4 cubic feet of interior space
• 500 Gallon Tank has 66.8 cubic feet of interior space
• 1000 Gallon Tank has 133.7 cubic feet of interior space

So if you have a 250 gallon tank and you think you've lost 10 gallons in a leak, then you've actually lost enough gas to fill almost 11 tanks of the same size. Using the gallons and cubic feet relationships above, it's fairly easy to understand that the true gallons lost in a leak are almost always a fraction of what an individual believes the gallons lost truly are.

Think about this...10 gallons of propane lost in a leak produces enough vapor to fill 560 propane grill cylinders!

Here's another example explaining the probability of actual gallons lost in a propane leak. Let's take a standard size 11" balloon (like a party balloon), which holds a volume of roughly .5 cubic feet and for the sake of this example, you think your tank has leaked 10 gallons of propane. 10 gallons of propane equals 363.9 cubic feet of vapor which will fill about 728 standard size party balloons. Some customers believe the gas they have lost is over 50 gallons and if they have in fact lost 50 gallons of propane, that's enough propane to fill 3,639 standard size party balloons. Just one gallon of propane which produces 36.39 cubic feet of vapor will fill almost 73 standard size balloons or 2 standard size (18 cu. ft) refrigerators.

• 1 Gallon of propane lost in a leak fills roughly 73 standard size party balloons.
• 5 Gallons of propane lost in a leak fills roughly 364 standard size party balloons
• 10 Gallons of propane lost in a leak fills roughly 728 standard size party balloons
• 25 Gallons of propane lost in a leak fills roughly 1820 standard size party balloons
• 50 Gallons of propane lost in a leak fills roughly 3639 standard size party balloons

As you can see, the actual amount of propane lost in a leak is far less than most people realize due to the volume of propane vapor that is produced by one gallon of liquid propane.