Safety valves are crucial devices in the industry. Indeed, these valves are simple and robust in their design. Safety valves are the ultimate overpressure device protection when all other devices are insufficient or failed. The poor design of these devices can be disastrous.
A conventional safety relief valve is mainly composed of a disk maintained pressed against a nozzle by a spring. When the pressure forces on the upstream face of the disk are below the force applied to the spring, the valve is closed. If an accidental overpressure event occurs in the process under protection, the pressure forces become high compared to spring elastic forces and the safety valve opens to relief pressure. Thus, the pressure in the process under protection is reduced to an acceptable value.
The force exerted by the pressure on a disk of a safety valve is essential for a correct design of the spring and the inner ring. To understand the forces, a safety relief valve was modified and the spring removed; a force measurement tool was mounted in order to measure the forces exerted at different inlet pressure and lift. These tests were made for several ring settings.
These measurements were made in incompressible fluid on a water test loop.
Finally, inlet and outlet conditions of the safety valves were modeled respectively by thermodynamic 1D-model. The safety valve is described by dynamic 1D-model where the hydrodynamics forces applied to the moving disk are provided by measurements in water.
