A pneumatic butterfly valve consists of a pneumatic actuator and a butterfly valve. It uses a circular disc that rotates with the valve stem to open and close, achieving the desired action. Primarily used as a shut-off valve, it can also be designed to have regulating or both shut-off and regulating functions. Butterfly valves are increasingly used in low-pressure, large- and medium-diameter pipelines.
Pneumatic butterfly valves are classified as: stainless steel pneumatic butterfly valves, hard-seal pneumatic butterfly valves, soft-seal pneumatic butterfly valves, and carbon steel pneumatic butterfly valves. The main advantages of pneumatic butterfly valves are their simple structure, small size, light weight, and low cost. These characteristics are particularly significant for pneumatic butterfly valves. They are conveniently operated when installed in high-altitude, concealed passageways and controlled by a 2-position 5-way solenoid valve, and can also regulate the flow rate of the medium.
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Working Principle of Pneumatic butterfly valve
Opening and Closing Process
Opening: Compressed air enters the pneumatic actuator chamber, pushing the piston to rotate. This rotation, via the valve stem, rotates the butterfly valve to 90°, fully opening the fluid passage.
Closing: When compressed air is switched to another chamber or the air supply is interrupted (single-acting type), the spring returns the valve to its original position, causing the butterfly valve to rotate in the opposite direction to the closed position, cutting off the fluid flow.
Regulation Process
By adjusting the air supply pressure or input signal (such as 4-20mA current), the rotation angle of the butterfly valve is controlled, achieving proportional flow regulation. For example, in chemical reactors, pneumatic butterfly valves can precisely control the raw material flow rate.
Pneumatic butterfly valve Structural Components
Valve Body
Cylindrical structure, connected to pipes at both ends, forming an internal fluid channel. Materials include carbon steel, stainless steel, and cast iron, adaptable to different media and operating conditions. For example, stainless steel valve bodies are suitable for corrosive media environments.
Butterfly Plate
Disc-shaped opening and closing element, its diameter matches the inner diameter of the valve body channel. Rotation changes the degree of channel opening. Some butterfly plates feature a spherical shape to improve sealing performance and extend service life.
Pneumatic Actuator
The core drive component, available in double-acting (compressed air drives the piston in both directions) and single-acting (spring return, automatically closing when air supply is interrupted). Actuators are mostly made of aluminum alloy, lightweight and corrosion-resistant.
Seals
Includes two types: resilient seals (such as rubber, PTFE) and metal seals (such as weld overlay alloys). Resilient seals are suitable for low-temperature and low-pressure conditions, while metal seals offer superior high-temperature and high-pressure resistance.
Accessories
Optional electro-pneumatic valve positioners, solenoid valves, air filter regulators, limit switches, etc., for automated control and status monitoring.
Pneumatic butterfly valve Performance Advantages
Quick opening and closing, easy operation
Opening and closing can be completed with a 90° rotation; low operating torque, labor-saving and convenient. For example, in emergency shut-off scenarios, pneumatic butterfly valves can respond quickly to prevent accidents from escalating.
Reliable sealing performance
The resilient sealing valve can achieve zero leakage under low pressure, while the metal sealing valve is resistant to high temperature and high pressure, and maintains its sealing performance even after more than 50,000 pressurized opening and closing cycles.
Excellent regulation performance
The flow characteristics are close to linear, and the regulation accuracy is high. For example, in cooling water systems of thermal power plants, pneumatic butterfly valves can precisely control water flow, optimizing equipment operating efficiency.
Compact structure and flexible installation
Small size and light weight, supporting flange and clamp connections, suitable for piping systems with limited space. For example, in fire protection piping of high-rise buildings, pneumatic butterfly valves can save installation space.
Low maintenance costs
The seals are replaceable, and the disc can be coated with a layer of material (such as nylon or PTFE) depending on the operating conditions to extend its service life. For example, in wastewater treatment plants, regular replacement of seals can reduce long-term maintenance costs.
Pneumatic butterfly valve Applications
Petrochemical Industry
Used for transporting crude oil, gasoline, acid and alkali solutions, etc., controlling fluid flow rate and direction. For example, in oil refining units, pneumatic butterfly valves can cut off high-temperature and high-pressure media, ensuring system safety.
Power Industry
Used in steam and water systems and cooling water systems to regulate media flow. For example, in boiler feedwater systems, pneumatic butterfly valves can precisely control demineralized water flow, preventing equipment overheating.
Metallurgical Industry
Used for transporting coal gas, oxygen, slurry, etc., adapting to harsh working conditions containing particulate media. For example, in blast furnace ironmaking, pneumatic butterfly valves can cut off dust-laden coal gas, preventing pipeline blockage.
Water Treatment Systems
Used in water supply and drainage, and sewage treatment pipelines to control water flow distribution. For example, in reverse osmosis water treatment equipment, pneumatic butterfly valves can regulate inlet water pressure, optimizing membrane module performance.
Food and Beverage Industry
Used for transporting pure water, beverages, and other clean media; materials must meet hygiene standards. For example, in beer production lines, pneumatic butterfly valves can prevent media contamination, ensuring product quality.
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