| Load Capacity | 100 N |
| Structure | Control |
| Valve Motion | Linear Motion Valve |
| Cast Iron | Cast Iron / Aluminum Die Cast |
| Stroke Length | 2" |
| Pressure | High Pressure |
| Country of Origin | Made in India |
Diaphragm actuators are pneumatically operated and they use an air supply from the control system or other sources. Diaphragm actuators are normally used for control valves, which are a type of globe valve that is typically used to regulate the fluid in order to adjust some process variables, such as pressure, temperature, or flow rate. Diaphragm actuators are used in all sectors of the oil and gas industry except for subsea. The most common styles for diaphragm actuators are known as “direct-acting” and “reverse-acting.” Fig. 2.12 compares direct-acting (right side) and reverse-acting (left side) diaphragm actuators used for the control valves. In direct-acting actuators, the air enters the top area of the diaphragm and pushes the diaphragm down. The air pressure, which is transferred to the diaphragm, overcomes the spring torque located under the diaphragm, so it pushes the valve stem down and closes the valve. Any failure in air supply leads to movement of the stem in an upward direction and the valve opens. Thus direct-acting diaphragm actuators are suitable for air-to-close (ATC) and fail-open (FO) applications. Most of the control valve actuators are reverse-acting, thereby providing a fail-closed (FC) mode of failure. In reverse port diaphragm actuators, the air supply port is located under the diaphragm, so the air supply opens the valve and a stoppage of the air supply leads to closure of the valve. The amount of force produced in this type of actuator depends on three main parameters: air pressure, diaphragm diameter, and spring force. Rotary diaphragm pneumatic actuators are the third type of diaphragm actuators and will be discussed later in this chapter.
