Which safety device should be installed on gas appliances to prevent backflow of gas?

The installation of a backflow preventer or a check valve on gas appliances is crucial as it serves the specific function of preventing backflow of gas into the supply lines. Backflow can occur when there's a drop in pressure within the gas system, potentially allowing gas to flow in the reverse direction. This can lead to hazardous conditions, including the risk of gas leaks or even explosions.

A backflow preventer or check valve ensures that any gas flow is unidirectional, allowing gas to flow toward the appliance while blocking any reverse flow that may occur due to pressure fluctuations. This mechanism is an essential safety feature to maintain the integrity of the gas supply system and protect both individuals and property.

While gas meters, shut-off valves, and expansion joints are important components of gas systems, they serve different purposes. Gas meters measure the amount of gas being used, shut-off valves are utilized to stop gas flow in emergencies, and expansion joints accommodate the movement or thermal expansion in gas lines. None of these devices provide the backflow prevention necessary for safe operation of gas appliances.