Working of Two stage pressure regulator valve

instrumentation

#1

What are pressure regulators?

The function of pressure regulator valve is to reduce the pressure and keep the pressure as constant as possible while the inlet pressure and flow may vary.

Two-stage pressure Regulator valve:

The double stage pressure regulator reduces the pressure inlet to a fixed pressure via two stages. The first stage, which is preset, reduces the pressure of the supply gas to an intermediate stage; gas at that pressure passes into the second stage.Two-stage regulators have two safety valves so that if there is any excess pressure there will be no explosion. A major objection to the single stage regulator is the need for frequent torque adjustment. If the supply pressure falls, the outlet pressure increases.

Construction and working of Double stage valve:

Dual stage pressure regulator valve

The two-stage regulator consists of two poppet valve mounted in opposite direction. These two valves have two pressure chamber and attached to a spring. The spring force for two valves can be adjusted to maintain the set pressure value. The spiral pressure adjustment screw can turn to adjust the set pressure. And there are two pressure gauges at inlet and outlet.

The inlet pressure is let to pass through the first poppet valve, the fluid faces the first stage valve completely. The first stage valve pressure is factory set and the spring exerts a pressure to open the valve. The inlet fluid pressure and spring pressure exerts in opposite direction. The released gas from the first stage valve is passed to the second stage poppet valve or to the intermediate pressure chamber.

Just like in the first stage there is adjustable spring to adjust the output pressure. The fluid pressure will be opposite to the spring tension. Depending on the spring tension a fixed pressure output is generated.

For example:

Suppose the inlet pressure is decreased, the first poppet value reduces the gap for airflow as the fluid pressure is less than the spring pressure. Thus a pressurised fluid is get filled in the pressure chamber or pressurise the second stage valve chamber. Now the equilibrium of the second stage is broken and the spring force becomes less and than the fluid pressure. This extra pressure acting on the second stage valve move the valve upward and closes the gap further, allow a small amount of fluid outwards and let remain the outward pressure constant.