Detailed introduction of AT pneumatic actuator

The actuator and regulating mechanism of pneumatic actuators are a unified whole, and their actuators include diaphragm type, piston type, fork type, and gear rack type. Piston type with long stroke, suitable for situations requiring high thrust; The thin film type has a smaller stroke and can only directly drive the valve stem. Fork type pneumatic actuators have the characteristics of high torque, small space, and torque curves that better match the torque curve of valves, but they are not very aesthetically pleasing; Commonly used on valves with high torque. Gear and rack pneumatic actuators have the advantages of simple structure, smooth and reliable action, and safety and explosion prevention. They are widely used in production processes with high safety requirements such as power plants, chemicals, and refineries.

Pneumatic actuator is an actuating device that uses pneumatic pressure to drive the opening, closing or regulating of valves, also known as pneumatic actuator or pneumatic device, but generally referred to as pneumatic head. This article elaborates on various technical requirements for pneumatic heads

　　AT series new valve pneumatic actuator

The AT new gear rack pneumatic actuator is designed by Shanghai What Company, which integrates the latest technologies at home and abroad, and innovatively optimizes the design through CAD three-dimensional models, resulting in a beautiful, compact, and modern appearance; And adopt practical new materials and new processes to make the quality and performance of the product more reliable; Multi specification selection is more cost-effective; The product fully complies with the latest international standards and technical specifications, meeting current and future needs.

① The gear rack dual piston symmetrical structure design ensures fast and stable movement, high precision, and high output power. By simply changing the piston assembly position, reverse rotation can be achieved.

② The extruded high-quality aluminum alloy cylinder body, with precision machined inner holes and outer surfaces subjected to hard anodizing treatment (anodizing+Teflon coating in special cases), has a longer service life and lower friction coefficient.

③ Integrated design, all double acting and single acting actuator models have the same cylinder block and end cap, making it easy to change the mode of action by adding or removing springs.

④ The combination pre loaded safety spring set can be conveniently and safely installed or the number of springs can be increased or decreased during assembly or on-site use.

⑤ Two separate adjustment screws on the external side are more precise and convenient for actuators already installed on the valve, adjusting the valve opening and closing positions. If full stroke adjustment is required, longer adjustment screws are also provided at the two end caps.

⑥ Multi functional position indicator, on-site visual indication, compliant with VID/VIE3845 and NAMUR standard slots, capable of installing and outputting all accessories such as limit switch boxes, electrical locators, position sensors (Beijiafu, Turck).

⑦ The air source interface complies with NRMAR standards and can be directly installed with NUMAR standard solenoid valves.

⑧ The composite material bearing shells and piston guide rings on the back of the rack, as well as the bearings on the output shaft, are designed to prevent metal to metal friction and increase lubrication, resulting in low friction and long lifespan.

⑨ All fasteners are made of stainless steel material, which is corrosion-resistant for a long time.

⑩ The connection part complies with the new international standard specifications ISO5211 and DIN3337 (F03-F25), making production and installation interchangeable and universal.

　　AT-DA dual acting working principle

When the air source pressure enters the middle chamber between the two pistons of the cylinder from the air port (2), the two pistons separate and move towards the two ends of the cylinder. The air in the two end chambers is discharged through the air port (4), and at the same time, the two piston racks synchronously drive the output shaft (gear) to rotate counterclockwise. On the contrary, when the air source pressure enters the air chambers at both ends of the cylinder from the air port (4), it causes the two pistons to move towards the middle of the cylinder, and the air in the middle chamber is discharged through the air port (2). At the same time, the two piston racks synchronously drive the output shaft (gear) to rotate clockwise. If the piston is installed in the opposite direction, the output shaft will rotate in the opposite direction, which is the double acting reverse DL type

　　Working principle of AT single acting pneumatic actuator

When the air source pressure enters the middle chamber between the two pistons of the cylinder from the air port (2), it causes the two pistons to separate and move towards the two ends of the cylinder, forcing the springs at both ends to compress. The air in the two end chambers is discharged through the air port (4), and at the same time, the two piston racks synchronously drive the output shaft (gear) to rotate counterclockwise. After the air source pressure passes through the solenoid valve, the two pistons of the cylinder move in the middle direction under the elastic force of the spring. The air in the middle chamber is discharged from the air port (2), and at the same time, the two piston racks synchronously drive the output shaft (gear) to rotate clockwise. If the piston is installed in the opposite direction, the output shaft will rotate in reverse when the spring returns, which is the single acting reverse SO type

When selecting pneumatic actuators, add a safety value to the torque of the determined valve, and increase the safety value by 25% for water vapor or non lubricating liquid media; Non lubricating slurry liquid medium increases the safety value by 30%; Non lubricating dry gas medium increases the safety value by 40%; The safety value of granular powder media transported by non lubricating gas is increased by 60%; For clean and low friction lubricating media, increase the safety value by 20% (the above safety values are recommended by our company's theory and are for reference only).

　　Example of DA type double acting actuator selection

When a pneumatic actuator controls a ball valve that requires a torque of 200Nm, the air source pressure is only 5bar, and the medium is non lubricating water vapor. Considering safety factors, increasing the safety value by 25% equals 250Nm. Use the double acting output torque table to find the air source pressure of 5bar, then search vertically along the column for torque data equal to or similar to 277Nm, and then search left along the row for its model, selecting DR00300 type.

　　Example of SR type single acting actuator selection

When a pneumatic actuator controls a butterfly valve that requires a torque of 100Nm, with a gas source pressure of 4.5bar and a non lubricating dry gas medium, considering safety factors, increasing the safety value by 40% equals 140Nm. According to the single acting output torque table, the spring reset endpoint is found to be a similar torque of 148Nm. Then, search for the endpoint torque of 158Nm at a gas source pressure of 4.5bar to the left along this line. It is necessary to consider the relative force balance between the gas source pressure torque and the spring reset torque, and then search for its model and number of springs along this line to the left. Choose SC00450 type and 9 springs.