The difference Between Single-acting and Double-acting Pneumatic Ball Valves

The single-acting pneumatic ball valves are available in normally open type, typically open for ventilation and closed for air spring return.

For double-acting pneumatic ball valves, ventilation opens, and in case of ventilation closure or air source fault, the pneumatic actuator resets the valve. These actuators boast rapid execution speeds, with the fastest switching occurring in 0.05 seconds per cycle, earning them the moniker of "pneumatic fast cut-off ball valves." Equipped with various accessories like solenoid valves, air source processing triplets, limit switches, positioners, and control boxes, pneumatic ball valves facilitate local and remote centralized control. This enables valve operation from a control room, eliminating the need for manual control at the site, particularly in hazardous or elevated locations, thereby saving time, labor, and enhancing safety.



Operating with pneumatic actuators, pneumatic ball valves require only a 90-degree rotation of the air source to achieve a tight closure with minimal torque. Featuring a fully equal valve body cavity for reduced resistance and a straight flow path, these valves are well-suited for direct opening and closing. Their compact structure, ease of operation, and maintenance make them ideal for a wide range of applications, including water, solvents, acids, natural gas, and other common working media. Moreover, they perform reliably even in challenging conditions with media such as oxygen, hydrogen peroxide, methane, and ethylene. The ball valve body can be either integral or modular, providing flexibility in installation and maintenance.

Maintenance and Guidelines for Pneumatic Ball Valves

Application: This manual pertains to electric or pneumatic ball valves with flanged connection ends.
Components: Comprises an electric or pneumatic actuator and the ball valve body section, connected via a bracket and connecting shaft.

Key Points:
(1). Temperature and Pressure Limits: The nameplate indicates the maximum operating pressure permissible for the ball valve at both maximum and minimum operating temperatures.
(2). Valve Seat and Seal Material: Utilize PTFE valve seats and seals, suitable for operating temperatures between 150°C and 200°C. Verify the compatibility of other seat and seal types for their operating temperatures.
(3). Nominal Pressure Level: The PN (nominal pressure) rating of a low-temperature valve denotes the maximum working pressure at normal temperature. For instance, PN4.0 signifies a maximum working pressure of 40 bar (4.0 MPa) within a temperature range of -290°C to 380°C.
(4). Actuator Instructions: Refer to the corresponding instruction manual for guidelines on electric or pneumatic actuators.

Explanation of single-acting and double-acting in pneumatic ball valves:

Single-acting and double-acting refer to the operational modes of pneumatic actuators used in ball valves.

Single-acting pneumatic ball valves: In this configuration, air pressure is applied to only one side of the piston within the actuator. The compressed air pushes the piston in one direction, either opening or closing the valve. The return action is achieved through a spring or an external force, depending on the design. Single-acting actuators are typically used in applications where the valve needs to fail in a specific position, such as fail-closed or fail-open.

Double-acting pneumatic ball valves: In this setup, air pressure is applied to both sides of the piston within the actuator. By alternating the air pressure between the two sides, the actuator can move the valve in both opening and closing directions. Double-acting actuators offer greater control over the valve position and are commonly used in applications where precise control is required.

Installation of pneumatic ball valves:

(1). Remove the protective covers from both ends of the flange and thoroughly clean the valve when fully opened.
(2). Prior to installation, conduct a complete system test using the specified signal (electricity or gas) to ensure performance is not affected by transportation vibrations. Install the wiring according to the electric actuator's circuit diagram once qualification is confirmed.
(3). Before connecting to the pipe, clean any remaining impurities in the pipe that could potentially damage the valve's seat and ball.
(4). Avoid using the actuator part of the valve as a lifting point during installation to prevent damage to the actuator and its accessories.
(5). Install Class valves horizontally or vertically along the pipeline direction.
(6). Ensure that the pipeline near the installation point does not experience external force. Utilize pipe supports to correct any pipeline deviations.
(7). After connecting to the pipe, securely tighten the flange connection bolts with the specified torque.

Operating procedures and usage of pneumatic ball valves:

(1). Prior to operation, ensure that both the pipes and valves have been thoroughly cleaned.
(2). Valve operation is initiated by driving the valve stem rotation in accordance with the magnitude of the input signal received by the actuator. A positive rotation of 1/4 turn (90°) closes the valve, while a reverse rotation of 1/4 turn (90°) opens it.
(3). To determine the valve's status: When the directional arrow on the actuator aligns parallel to the pipeline, the valve is in the open position. Conversely, when the directional arrow is perpendicular to the pipeline, the valve is closed.