Overview
The Alcon U21-33-21-12 is a robust 2/2 direct-acting solenoid control valve from Alcon’s 21 Series. This valve is engineered for precise on/off flow control of air, hydraulic fluid, and other media in industrial automation, pneumatic, and fluid power applications. Direct-acting design means the solenoid coil supplies all power needed to open the valve, enabling operation from zero pressure and eliminating the need for external pilot pressure.
Key Features
- 2/2 direct-acting design — energize to open, de-energize to close
- Normally closed (NC) configuration for fail-safe operation
- Maximum operating pressure up to 100 bar (1450 psi)
- Compact aluminum or ductile iron body construction
- Fast response time — reliable on/off switching
- Available in 1/8″ or 1/4″ NPT/BSPT port sizes
- Choice of seal materials (EPDM, PTFE, or other configurations)
- Suitable for air, water, oil, and compatible fluids
Technical Specifications
- Series: Alcon U21 (21 Series)
- Configuration: 2/2 valve, normally closed
- Valve Type: Direct-acting solenoid, on/off
- Maximum Working Pressure: 100 bar
- Port Sizes: 1/8″ or 1/4″ NPT / BSPT
- Mounting: Manifold or inline connection
- Body Material: Aluminum or ductile iron options
- Seal Material: EPDM, PTFE, or custom materials
- Operating Temperature Range: Typically -10°C to +80°C (confirm for sealing material used)
- IP Rating: IP65 standard enclosure
- Certifications: UL approved, CE mark where applicable
Typical Applications
The U21-33-21-12 is well-suited for:
- Pneumatic automation and control systems
- Hydraulic fluid distribution and circuit control
- Industrial air systems and compressed-air circuits
- Burner and heating system controls
- Machine tool and press applications
- On/off solenoid switching for valving manifolds
- Laboratory and test equipment fluid routing
- OEM and retrofit applications requiring general-purpose solenoid valves
Compatibility & Replacements
Compatible With
- Standard pneumatic and hydraulic control systems
- Industrial automation manifolds and circuit designs
- Pressure ratings from 0 to 100 bar
- NPT and BSPT threaded port standards
- 24 V DC and AC coil configurations (verify coil voltage for your unit)
- Mobile, industrial, and stationary equipment
Replaces / Drop-In Replacement For
Verify compatibility with your system integrator or refer to Alcon/Rotork documentation. Other models in the U21 series include U21-31-21-12, U21-32-21-12, U21-41-21-12, U21-42-21-12, and U21-43-21-12. Consult the original equipment documentation before ordering a replacement.
Works With
- Pneumatic control circuits and systems
- Hydraulic power units and manifold assemblies
- Industrial PLC and automation control platforms
- Standard solenoid coil drivers and switching modules
- NPT and BSPT threaded systems
- Rotork (parent company) product ecosystems
