Which of the following is a sign of a leak in an LP gas system?

A hissing sound in an LP gas system is a critical indicator of a gas leak. This sound typically occurs when gas escapes from the system due to a breach, such as a crack in a pipe or a faulty valve. The hissing noise is a direct result of gas under pressure exiting the system and indicates that there is an uncontrolled release of LP gas, which can pose significant safety risks, including fire or explosion.

High pressure readings would not necessarily indicate a leak because they can occur for various reasons, such as temperature fluctuations or system malfunctions not related to leaks. The absence of odor—due to LP gas being odorless in its natural state but usually mixed with an odorous agent—does not signal a leak and, in fact, might mask the presence of a leak, leading to unsafe conditions. Warm air coming from the tank could suggest several issues, but it wouldn’t reliably signal a leak specifically. Therefore, the presence of a hissing sound is the most direct and clear sign that there is an issue with the LP gas system requiring immediate attention.