Pneumatic Valve Festo Type VL/O-3-1/4-1/2 Full Specification
Original Model: VL/O-3-1/4 (Festo Part No.9984), -1/2 stands for customized upgraded version with G1/2 main ports instead of standard G1/4. Belongs to Festo Classic Tiger Series 3/2-way pneumatically piloted poppet valve, single pilot operated with spring return, convertible between normally closed & normally open configurations, widely used to replace 23Q-L8 & VSP3301-31 slide valves for pilot control circuits.
1. Model Coding Definition
Code Description
VL Festo pneumatic pilot valve series
/O Convertible design (swap internal seal to switch NC/NO function)
3 3 ports, 2-position (3/2-way valve)
1/4 Standard main port: G1/4 parallel British pipe thread
-1/2 Custom version: main ports upgraded to G1/2 thread for high flow
Standard Port Nomenclature
- Port 1: P (Air Supply Inlet)
- Port 2: A (Outlet to Actuator)
- Port 3: R (Exhaust Port)
- Port 12/110: G1/8 pilot control port
2. Technical Parameters
- Construction: Poppet seat valve, soft NBR sealing, zero internal leakage
- Operation: External pneumatic pilot actuation + mechanical spring return (monostable)
- Nominal Bore: 7mm (standard VL/O-3-1/4); 12mm (G1/2 upgraded version)
- Rated Flow Rate: 800 L/min (DIN1343 standard); 1600 L/min for G1/2 model
- Working Medium: Filtered compressed air conforming to ISO8573-1:2010 [7:4:4], optional oil mist lubrication
- Working Pressure: -0.095MPa ~ 1.0MPa (-0.95bar ~ 10bar, compatible with vacuum circuit)
- Pilot Operating Pressure: 0.1MPa ~ 1.0MPa (1~10bar)
- Temperature Range: Ambient & medium -10℃ ~ +60℃; storage temp -20℃ ~ +60℃
- Material: Die-cast aluminum body, NBR oil-resistant seals, IP65 protection class
- Switching Time: ON 7ms, OFF 26ms
- Mounting: Through-hole base mounting / PAL & PRS manifold rail mounting, any installation orientation
- Weight: 230g (standard model); 380g (G1/2 version)
3. Working Principle (2 Configurations Convertible)
① Factory Default: Normally Closed (NC)
- No pilot air to port12: Port1 blocked, port2 connected to exhaust port3 → actuator depressurized
- Pilot air supplied to port12: Poppet lifted, port1 connects to port2, port3 sealed → actuator pressurized
- Pilot air cut off: spring resets automatically to depressurized state
② Modified: Normally Open (NO)
Disassemble valve and reposition internal sealing washer to convert:
- No pilot air: port1 directly communicates with port2 for continuous air supply
- Pilot air input: supply cut off, port2 vents via port3
4. Product Advantages
1. Poppet structure resistant to dust, moisture and impurities, more reliable than slide valves for oilfield & heavy machinery harsh conditions
2. Dual NC/NO convertible design, one stock valve for two circuit demands
3. Compatible with both positive pneumatic pressure and vacuum applications
4. Exhaust port fit for throttle silencer to adjust cylinder actuation speed
5. Modular design for manifold bank assembly to integrate complex air circuits
5. Main Applications (Matched with QF501A Air Switch)
Combined with QF501A two-port manual air switch as full pilot control assembly, substitute 23Q-L8 / VSP3301-31 slide valves for:
- Clutch & pneumatic brake pilot control of drilling rigs & workover rigs
- Directional control for pneumatic cylinders, clamps and locking units
- High flow air on-off for mining equipment & automation production lines
- Vacuum suction circuit switching