Final answer:
When performing a regulator lock up test, if pressure exceeds the safe limit of 14 inches water column, the regulator may need adjustment or replacement. It's important to account for air temperature, as per Gay-Lussac's Law, since pressure readings vary with temperature.
Step-by-step explanation:
While performing a regulator lock up test on a propane tank, if the pressure exceeds 14 inches of water column, it indicates a potential malfunction of the regulator, which could lead to too high a pressure output. This is a safety concern and the regulator must be adjusted or replaced. Keeping Gay-Lussac's Law in mind, it is important to remember that the pressure reading on the gauge can vary with temperature. On a hot day, the pressure inside the propane tank may read higher due to temperature effects, so the ambient air temperature must be taken into account when interpreting gauge readings during a regulator lock up test or when determining propane levels.