Propane in its natural state is a colorless, odorless gas. An odorant is added to help detect leaks. Propane is sold in tanks as a liquid which will expand 270 times in volume as a gas. This gas is heavier than air and will seek the lowest level available.
Read all label warnings and equipment instructions. Most newer barbecues and appliances come with an instruction plate securely attached in an obvious place.
Make a visual check for leaks, dents, damage, and corrosion -- especially around the nozzle. In addition, apply soap and water to these areas and look for bubbles, the presence of which will indicate a leak (in rare instances, propane gas will experience "odor-fade" so don't depend solely on sniffing to detect leaks).
After prolonged storage, check valves and openings for spider webs and other obstructions. Often the appliance gas jet orifices become clogged with grease and soot. This will be indicated by a gold or orange flame. Have the jet's orifices cleaned so that a blue flame is seen. Also, check the connector at the end of the hose and regulator assembly.
Most connectors have an O-ring near the nose to assist in forming a seal against leaks. If the O-ring appears worn or damaged, replace it according to the manufacturer's recommendations.
On barbecues, always open the lid before lighting. If ignition does not take place, turn the control valve off, wait for five minutes, and repeat the lighting procedure. When you are finished, close the valve on the cylinder first, to allow the propane in the hose to be used up. After the burner is extinguished, turn the control to the "off" position.