water heater safety valves

 

 TPR (temperature and pressure release valve) or T&P valve

On the side or top of your water heater tank is a valve connected to a metal or plastic discharge tube pointing downward. The valve is called a T & P valve, or TPR valve, for temperature and pressure relief. If all goes well, a TPR valve never gets used except during testing. But in the event of an emergency or malfunction, this valve is of critical importance. It can potentially prevent your water heater from exploding.


In a standard water heater, the water is heated by a gas burner or electric elements. As the water reaches temperatures between 49 and 60 degrees Celsius , both the water and the water heater's metal tank expand. Some expansion is normal, but too much expansion is unsafe. When the temperature reaches 99 degrees Celsius or the pressure reaches 150 psi (pounds per square inch) or 10.3 bar, a properly functioning T & P valve opens and expels hot water and steam through the discharge tube. 

pressure relief valve in coffee machine

most are rated at 2 to 2.2 bar

OPV