The selection of a suitable pneumatic actuator for industrial needs needs needs to comprehensively consider the characteristics of the valve, operation needs, gas source conditions, environmental adaptability and safety factor. The following are the specific analysis and suggestions: 

 I. Clarify the valve type and torque requirements 

 1. The valve type affects the torque 

 Ball valve: The contact area between the ball body and the valve seat seal is small but the pressure is high, and it requires greater torque to overcome the sealing friction. For example, the torque of the ball valve under the same caliber may be 20%-30% higher than that of the butterfly valve. 

 Butterfly valve: The torque is composed of sealed friction moment and medium pressure moment. The friction force of soft sealed butterfly valve is relatively small, and the hard seal needs to consider metal friction. 

 Gate valve/slut-off valve: requires a straight-stroke actuator, and the torque is related to the friction and medium pressure of the valve stem. 

 2. Torque calculation and safety factor 

 Calculate the theoretical torque according to the valve caliber, working pressure and sealing form (soft/hard seal). 

 Safety factor suggestions: 

 Water vapor or non-lubricated liquid media: increase the safety value by 25%. 

 Non-lubricating slurry liquid medium: increase the safety value by 30%. 

 Example: The Valve Requires 210Nm Torque, The Medium Is Non-Lubricated Water Vapor, And The Safety Value Needs To Be ≥262Nm, And The Model With An Output Torque Of 277Nm Is Selected (Such As POADA300). 

 II. Match the action speed and control requirements 

 1. Quickly cut off the scene 

 It is suitable for emergency safety systems (such as boiler drainage and gas cut-off), and you need to choose a fast-moving actuator. 

 Key parameters: cylinder size, intake flow rate, exhaust mode. The response time of the gear-rack actuator can be as short as 50ms. 

 2. Fine adjustment of the scene 

 When the flow control accuracy requirement is high, the speed of slow motion is required, which can be adjusted by the gas throttle valve. 

 Adjustable actuator: equipped with a locator to realize continuous adjustment of 4-20kPa signal, with a positioning accuracy of ±0.1%. 

 III. Evaluate the conditions of the gas source 

 1. Air source pressure range 

 The common gas source pressure is 0.4-0.6MPa, but the requirements of different models of actuators may be different. 

 When the pressure is unstable: install a pressure regulator to ensure the normal operation of the actuator. 

 2. Quality treatment of gas source 

 Gas sources containing moisture or impurities need to be equipped with gas source processing units (air dryers, filters). 

 Anti-condensation measures: In a low-temperature environment (below -50°C), it is necessary to prevent condensation from freezing. 

 IV. Adapt to the environment and working conditions 

 1. Explosion-proof requirements 

 Petrochemical and natural gas industries need essential explosion-proof actuators (in accordance with ATEX and IECEx standards). 

 Pneumatic advantages: no electric sparks, suitable for flammable and explosive environments. 

 2. Adaptability to harsh environments 

 High humidity/salt spray: choose stainless steel material + anti-corrosion coating (such as nickel-plated, epoxy resin). 

 Dust environment: The anti-dust intrusion ability of pneumatic actuators is better than that of electric actuators, which is suitable for mining and metallurgical industries. 

 3. Large thrust demand 

 Large valves (such as gate valves and ball valves above DN1000) require high-thrust actuators. 

 Solution: Increase the cylinder diameter or series cylinder, and the cost is lower than that of the same-thrust electric actuator. 

 V. Actuator type selection 

 1. Straight stroke vs angle stroke 

 Straight stroke: membrane type, piston type, suitable for gate valves and shut-off valves. 

 Thin-film type: simple structure, low cost, thrust is limited by the diaphragm area, suitable for low-pressure small-caliber valves. 

 Piston type: large output force, high pressure resistance, suitable for large-caliber high-pressure valves. 

 Angle stroke: gear rack type, fork type, suitable for ball valves and butterfly valves. 

 Gear rack type: stable torque and high control accuracy, widely used in chemical and natural gas pipelines. 

 Fork type: large torque and small space, suitable for heavy valves in the metallurgical industry. 

 2. Single action vs double action 

 Single function: spring reset, suitable for safe shutdown occasions (such as emergency shut-off valve). 

 Dual action: the air source drive opens and closes, and the output torque is larger, which is suitable for frequent operation. 

 VI. Selection decision tree 

 1. Give priority to the scenario of pneumatic actuator: 

 There are flammable and explosive risks (such as oil, gas and dust environments). 

 Rapid cut-off or high-frequency action is required (such as switching >10 times per minute). 

 There is a ready-made gas source at the site, or large-caliber, high-pressure valves need to be driven (such as DN≥600). 

 2. Give priority to the scenario of electric actuator: 

 Precise flow regulation or position control is required (such as control valve, analytical instrument sampling valve). 

 There is no gas source or it is difficult to deploy gas sources (such as remote areas and mobile devices). 

 It needs to be integrated into intelligent systems (such as PLC/DCS remote monitoring and fault self-diagnosis). 

 VII. Notes on special scenes 

 Low-temperature environment: pneumatics need to prevent condensation from freezing, and electrics need to choose low-temperature motors (such as -60℃ special grease). 

 High humidity salt fog: pneumatic actuators need stainless steel + anti-corrosion coating, and electric actuators need IP68 protection + anti-corrosion coating. 

 Emergency backup: Important valves can use "pneumatic + electric" double-motion actuators (mainly pneumatic, electric for emergency backup). 

 Kinko fluid, professional manufacturer of pneumatic actuators, service hotline: +86-133 5611 9006