For your own safety, don’t play around with gas.

If you can smell gas, then more than likely, there will be a leak in the installation. Common leaks are found with soapy water around the gas cylinder regulators or around the gas fitting connections to the appliance.  Lpg or cylinder gas is heavier than air and will fall directly to the floor and stay there, in the case of a leak. If there is no breeze or ventilation then this gas will mix with the surrounding air until the correct mixture is achieved for ignition.  When this occurs it is a very dangerous situation.  Natural gas is lighter than air and will disperse more readily than lpg, however the same situation can still arise.  Gas leaks need to be repaired by trained technicians