Removing the propane tank from your gas cooking grill is typically an easy task. You only need a couple of tools to do the job safely, and pulling the gas supply from your outdoor cooking unit is something that absolutely requires basic safety precautions. Always extinguish all open flames and do not smoke while performing the job. Never change a propane tank in an enclosed space such as a garage because a small amount of gas will always emit from the tank and regulator connection. Change propane tanks outdoors.
Close the top main valve on the small propane tank. Observe the arrows imprinted on the top of the valve. Turn the valve in a clockwise direction.
Place the open jaws of the crescent wrench over the large nut of the tank's gas regulator. The nut is located at the mating point of the propane tank and the gas regulator. Use the wrench's thumbscrew to close the jaws around the large nut.
Turn the wrench in a clockwise direction to loosen the connection. Typically, most gas connections for small appliances use a left-handed thread for flammable gases.
Loosen the nut with the wrench. Continue removing the nut by hand until you can pull the neck of the regulator from the propane tank connection. You may catch a small whiff of gas as the regulator's neck is pulled from the propane tank. There is always a small amount of gas at this connection point.
Pull the tank from the gas grill's cart. In some models, this may entail loosening a safety strap. Place the empty tank in a safe location, outdoors and well away from any flame sources.