Overview
Pneumatic solenoid valves are industrial components controlled by electromagnetism, serving as basic automation elements for fluid control. They are widely used in industrial control systems to adjust the direction, flow rate, speed, and other parameters of compressed air and other media.
Normally Open & Normally Closed Solenoid Valves
- Normally Closed (NC): The air passage is blocked when de-energized; airflow is enabled only when powered on. This is the most commonly used type in on-site applications.
- Normally Open (NO): The air passage remains open when de-energized; airflow is cut off only when powered on.
- Selection Logic: For long-term continuous airflow (e.g., 23 hours of flow, 1 hour of cutoff), a normally open solenoid valve is preferred to minimize continuous power consumption.
Solenoid Valve Ports, Positions and Control Types
- Number of Positions: Refers to the number of operating positions of the valve spool, visually represented by boxes in schematic diagrams.
- Number of Ways: Refers to the number of air ports, typically 5 ports in standard pneumatic solenoid valves.
- Single Solenoid Control: Equipped with one coil; the valve automatically resets when de-energized.
- Double Solenoid Control: Equipped with two coils; maintains its last state when de-energized.
Key Features and Structure
- Model Parameters: Indicate pipe diameter, voltage rating, valve series, and functional specifications.
- Manual Test Button: Allows manual spool actuation without electrical power, effective only when air pressure is supplied.
- Throttle Adjustment: Counterclockwise adjustment increases cylinder actuation speed; clockwise adjustment reduces speed.
Cylinder Actuation Principle
- Air flows from inlet port P to A → Cylinder retracts, with exhaust air discharged through B to S.
- Air flows from inlet port P to B → Cylinder extends, with exhaust air discharged through A to R.
Manifolds and Valve Islands
- Manifold Blocks: Allow installation of multiple solenoid valves, sharing air supply and exhaust paths. Each valve typically requires one PLC output (Q-point).
- Valve Islands: Use communication control to replace discrete wiring, greatly reducing the number of required PLC Q-points.
- Pneumatic Fittings: Push-in connectors for easy tubing installation; press the collar to release tubing.
Pneumatic Air Preparation Components
- Oil-Water Separator: Filters moisture, oil, and impurities from compressed air generated by air compressors.
- Pressure Regulator: Reduces and stabilizes inlet air pressure (only capable of pressure reduction).
- Mist Lubricator: Supplies lubricating oil to cylinders and solenoid valves to reduce wear during continuous operation.
- Mufflers & Plugs: Mufflers reduce exhaust noise; plugs seal unused ports on manifold assemblies.
