Propane cylinders should be stored right side up to prevent any leaking from the opening valve. When you are not using the tank, always close the valve. While most tanks have a built-in safety that stops the liquid gas from leaking out when open, it still is possible for the gas to escape when open.
Transport the cylinder upright and never on its side or held so that the top of the cylinder is facing the ground. When transporting in a vehicle, the cylinder should be secure and not able to move freely; some disturbances of the tank can cause leaks and tears in the tank.
If a house is built with propane devices, have them inspected if you smell propane, or if they haven't been checked in over a year.
As of 2010, propane tanks are fitted with overfill protection devices (OPDs). These prevent a tank from being overfilled and losing excess gas when heated. They also prevent gas from leaking when the tank is not attached to a device.
Propane should never be stored inside a building as the risk of carbon monoxide is possible with propane. If you feel nauseated, lightheaded, have a headache, feel muscle weakness or have any signs of CO poisoning, head to fresh air immediately. Call your propane inspector immediately if you have these symptoms.