Final answer:
Appliances used for heating water or storing hot water must be protected by a pressure relief valve to prevent over-pressurization or explosions. This valve opens and releases excess pressure in the system to ensure safety. It is crucial in hot water heaters and other similar appliances.
Step-by-step explanation:
Any appliance used for heating water or storing hot water must be protected by a pressure relief valve. This valve is designed to open and release excess pressure in the system, preventing the appliance from over-pressurizing or exploding. It ensures the safety of the appliance and the people using it.
For example, in a hot water heater, the pressure relief valve is a crucial component. If the temperature or pressure inside the tank exceeds safe limits, the valve opens, allowing excess pressure to escape. This prevents damage to the appliance and reduces the risk of injury or property damage.
In summary, a pressure relief valve is necessary to protect appliances used for heating water or storing hot water from potential damage caused by excessive pressure.