The working principle of a relief valve is relatively straightforward. It typically features a spring-loaded mechanism that holds the valve closed under normal operating conditions. When the pressure in the system exceeds the designated limit, the force exerted by the fluid overcomes the spring tension, allowing the valve to open. This action releases the excess fluid, effectively lowering the pressure within the system back to a safe operating level. Once the pressure drops, the spring mechanism pushes the valve back to its closed position, ready to operate again as needed.