Pressure Regulator Valves Maintain Downstream and Upstream P

There are two types of pressure regulator valves, the one that maintain downstream pressure and the other one that maintain upstream pressure. The pressure regulator valves usually used in the process application that doesn’t need an accurate pressure control (fluctuation or offset up to 20% is acceptable). So, actually how this pressure regulator valve operate to maintain downstream or upstream pressure?

Pressure regulator valves maintain downstream pressure

The most used pressure regulator valves are the valves that maintain its downstream pressure. This valve is a normally open valve. Here is the step by step operating principle of this valve.

Valve didn’t operate; the valve is on the Normally Open position.

The system start to operate; the fluid flow comes in through the valve and built a pressure in the downstream of the valve.

Since the downstream pressure keep rises, it goes to push the diaphragm of the valve through the feedback line. When the diaphragm pushed out, the stem that holds the plug also goes up (start to close).

When the downstream pressure of the valve reaches above the set pressure, it pushes the diaphragm to its maximum expansion and caused the plug to move up and close the valves.

Once the downstream pressure is going down, the diaphragms will also lesser push out thus the plug slowly move down and the valve will open.

Above mechanism (from point no. 2) is repeated again and so on.

Pressure regulator valves maintain upstream pressure

The other type of pressure regulator valve is the one that maintain upstream pressure. The operating principle of this valve is same with the valves that maintain downstream pressure except the plug and the flow in that put inversely. Here is the step by step operating principle of this valve.

Valve didn’t operate; the valve is on the Normally Close position.

The system start to operate; the fluid flow didn’t pass through the valve (Normally Close valve) and built an upstream pressure of the valve.

Since the upstream pressure keep rises, it goes to push the diaphragm of the valve through the feedback line.

When the upstream pressure of the valve reaches above the set pressure, it pushes the diaphragm to its maximum expansion and caused the plug to move up and open the valves.

Once the upstream pressure is going down, the diaphragm will also lesser push out thus the plug slowly move down and close the valve.