Never take a propane cylinder indoors if it contains, or has contained, propane. This is dangerous and unlawful. When purchasing a new cylinder, be sure that it is the size that fits your appliance bracket. Some connectors have a hand wheel requiring only hand tightening. Ensure all connections are tight before operating your propane appliance.
Propane is both odourless and colourless when produced.
However, in order for you to detect the presence of propane, an odour-producing substance is added to it by the propane producer. If you detect such an odour, don't light a match or turn an electrical switch on or off. Turn off the cylinder valve, ventilate the area and search out the source of the leak. Make up a soap and water solution. Turn the cylinder valve on.