Markco Diaphragm Actuator – PD Series

Its working principle involves the supply pressure entering the diaphragm chamber and acting on the diaphragm to generate thrust, which moves the actuator push rod while compressing the spring until it balances with the spring’s reaction force, positioning the push rod at the predetermined location. Suitable for linear control valves, it is ideal for proportional regulation and on/off control applications, and also highly applicable to other linear motion devices.

Product Features:

• Wide Range of Applications — Available in 5 actuator types and 8 sizes, offering extensive applicability. Multiple specifications for spring stiffness, travel limiters, and manual devices are provided, making it suitable for almost any control valve application.

• Excellent Linearity Between Load Pressure and Travel — The molded diaphragm moves within a deep-drawn casing, minimizing changes in the effective diaphragm area across the entire travel range.

• High Output Force — For the available diaphragm sizes, the molded diaphragm and deep-drawn casing can withstand high pressures to deliver maximum thrust.

• Good Dynamic Stability and Frequency Response — The shallow supply-side casing results in a smaller chamber volume on that side, thereby minimizing response time.

• Capable of Handling High Thrust — The molded diaphragm provides maximum thrust corresponding to the diaphragm size.

• Long Service Life — Robust thick-walled cast iron and steel construction ensures high stability, corrosion resistance, and prevents actuator deformation under overpressure conditions.

• Suitable for Low-Temperature Applications — All diaphragm actuator sizes feature enhanced specifications for use in temperatures as low as -50°C.

• Rigid Connection — The split-type stem connection clamp block facilitates easy installation and ensures robust motion transmission, helping to avoid non-movement and imprecise valve positioning when disconnected.