Answer: Gas grills, whether fired by natural gas, or (bottled gas), are neat and convenient. Whether they are the relatively cheap disposables or the gussied up $2000 grills, their functions are quite similar ? all have gas burners much like gas kitchen stoves. The more expensive will, or should, deliver more heat, have more space, be sturdier and have sideboards and accessories. But, if the el cheapo can deliver at least 30,000 BTU's, it will broil a steak and cook a roast ? which is about all any gas grill can do.
In grills, propane or butane (bottled) gas will usually produce more BTU's than natural gas in grills because propane is delivered at a higher pressure, and therefore more gas is available for burning at any given time. It also produces more BTU's per cubic foot of gas. Propane gas pressure is adjustable by a pressure regulator which normally provides gas at 6.3 ounces per square inch. Natural gas is normally delivered to households at 4 ounces per square inch.
Because liquid is more dense than gas, butane and propane are bottled under pressure in their liquid state. Their low boiling points causes them to make a phase change to gas when the bottle valves are opened. Propane's boiling point is higher than either natural gas or butane which is why propane is more widely used as bottled gas than butane. If you have a choice, go with the propane.
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