Which safety feature is primarily associated with gas appliances?

Gas appliances are equipped with several safety features that work together to ensure safe operation and to mitigate risks associated with gas usage.

A pressure regulator is an essential component that controls and maintains the correct gas pressure within the appliance, ensuring it operates within safe limits. This helps prevent gas leaks and potential overpressure situations that could lead to hazardous conditions.

A shut-off valve is another critical safety feature, as it allows for the immediate cessation of gas flow should an emergency arise. It's especially important for quickly isolating the appliance during maintenance or in the event of a detected leak.

A flue or vent plays a vital role in safely exhausting combustion gases, such as carbon monoxide, outside of the living space. This ensures that harmful gases are not trapped within the building, protecting the occupants' health and safety.

Since each of these features contributes significantly to the safe operation of gas appliances and addresses different aspects of gas handling, the answer encompasses all of them. Therefore, the safety of gas appliances is best represented by the collective presence of a pressure regulator, a shut-off valve, and a flue or vent.