Propane is stored in liquidsource::www.swvagasservice.com form in a steel storage container commonly referred to as a propane tank. Propane tanks come in many shapes and sizes, and most were designed to have a safety margin of 5 to 1. This means the tanks were designed to hold five times their normal working pressure, which makes them very safe, but it's important to note that your propane tank should never be moved or disconnected without first contacting your gas supplier. If you need a tooth pulled call the dentist, if you need gas work done call the gas company. It usually produces better results than doing it yourself.
Propane tanks are usually referred to by the amount of water they will hold or water capacity. Therefore a "500 gallon tank" would be a tank that has a water capacity of 500 gallons. It's common knowledge that water expands and contracts with change in temperature, but few people realize propane can expand up to 17 times the amount water will over the same change in temperature. Therefore, to prevent too much pressure from building in the tank, they are only filled to a maximum of 80-85% of their water capacity to allow for the expansion and contraction of the propane. So 85% of a 500 gallon tank would be 425 gallons. This is the maximum amount of propane that can be put in that tank. Because of the considerable expansion and contraction of the liquid propane, the gauge on the tank is not an exact reflection of how much propane is in the tank. The only exact method of determining the amount of propane in the tank would be to weigh it. Weighing 500 gallon tanks each time you fill them is not a very practical thing to do, so we settle for the reading on the gauge. It is not uncommon to fill a tank on a warm April day and leave it turned off, only to return on a chilly October morning and find it will hold a few more gallons due to liquid contraction.
Under your tank's lid you will find a round or star shaped hand wheel which shuts off the supply of gas to the house. It operates the same way as a water spigot, as turning it clockwise will stop the flow of gas and turning it counterclockwise will start the flow of gas. Unlike a water spigot, there is no halfway when dealing with a propane valve, either turn it all the way open and "snug it", or all the way closed and "snug it". Obviously, knowing how to turn the gas off is something all gas customers should know, so if your not sure how to do it call your gas company. Also under the lid is usually where you will find the liquid level gauge which can give you an estimate of how much propane is in the tank.
__The propane tank placed at your home is inherently safe, but let me take this opportunity to discuss a different kind of propane tank; the "grill tank". This is the small 20lb. tank that you use with gas grills. These tanks are also very safe, until you stop following the manufacturer's recommendation and store it indoors. The place for any propane tank is outside, not in the garage, basement, or anywhere that is a confined space. If you have any questions, refer to the information provided by the manufacturer.