What's the difference between LPG or natural gas?

by | Dec 30, 2008 08:00 PM ET

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Marshall Brain

Hi, I'm Marshall Brain with today's question. When you're buying gas appliances, why do you always have to specify whether you're using LPG or natural gas? If you've ever shopped for a gas grill, gas fireplace logs, a gas stove or a gas dryer, you know that you're always asked to specify whether you plan to use it with natural gas or LPG, also known as liquefied petroleum gas. The reason you have to get it right is because LPG and natural gas have very different properties. Natural gas is just that - it's natural. If you sink a well in the right spot, natural gas flows out of the ground. It's mostly methane, or CH4.

Liquefied petroleum gas, on the other hand, is a product of crude oil distillation. It contains mostly propane, or C3H8. Propane has a very nice property that when you compress it, it easily condenses into a liquid. This means that it's much easier to store in a tank than natural gas, which doesn't compress easily. You can see the difference between natural gas and LPG most easily when you buy a gas stove. Normally, you're supplied with two sets of jets: one set for natural gas and one set for LPG. You install one jet in each burner. The jet is simply a little screwing cap with a hole drilled in it.

The difference is that the hole in the jet for natural gas is bigger, about twice as big as the hole in the jet for LPG. The reason for this difference is because LPG contains much more energy than natural gas does. A cubic foot of natural gas contains something like 1,000 BTU of energy. A cubit foot of propane contains maybe 2,500 BTU. You can see that if you take a gas appliance set up for natural gas and you run it on LPG, the appliance is gonna run hot. In some appliances, that extra heat is a fire hazard. In others, like a gas grill, it means that the grill is either gonna be way too hot or way too cold if you use the wrong jet.

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