A safety valve is usually a mechanical valve controlled by a preset spring pressure. The safety valve consists of a steel spring in the middle,... The safety valve spring keeps the valve closed. If the system pressure increases, the system pressure overcomes the force in the safety valve spring, which results in the spring in the safety valve being compressed. Now the safety valve will open and blow off the excess pressure that has arisen in the system. When the safety valve has opened and blown off the excess pressure to normal operating conditions, the spring in the valve will overcome the force in the system causing the valve to close again.
The spring force is important for a safety valve, as an incorrectly set valve risks leading to an explosion in the worst case scenario. If, on the other hand, the spring is broken, the valve will not be able to withstand the system pressure, which leads to it blowing off continuously and creating a financial loss as expensive media is blown off via the safety valve.