Butterfly Control Valves

Another type of pneumatic-assisted control valve is a butterfly valve. From the diagram, notice that the valve mechanism for this type of valve has a valve plate with a rod mounted through its axis that becomes the valve stem.

The valve’s pneumatic control mechanism is linked to the valve stem so that it can be rotated to cause the valve plate to move to a position that’s horizontal with the flow or vertical to the flow, which would cause the flow to stop.

When air is sent to the pneumatic chamber of the valve, it will press on a diaphragm and cause the valve linkage to move up and down. In this type of valve, the up-and-down movement causes the valve stem for the butterfly valve to rotate to the open or closed position. Springs provide the counterbalance to the diaphragm, which allows the valve to be proportional.


Butterfly Valve design is the most common type of rotary valve and provides low weight to Cv Ratio combined with simplicity of design and comparatively low cost. It is a simple device to control or block the flow, a single vane or wafer disc pivots in the valve body.

They can be found on a wide variety of applications for throttling or two position control in the chemical, paper and pulp, sugar industries, cooling water circulation, water treatment plants, compressed air, gas plant, flue gas desulphurisation plants etc.

Butterfly Valves have been around the industry for decades, performing well defined tasks and are Economic alternative to Gate valves, Ball valves, Plug valves etc