Direct-operated solenoid valve WL 9902

2-wayairfor compressed air

Overview
A fluid proportional valve is an industrial valve component that regulates flow, pressure, direction, or actuator speed based on an input signal. The valve provides variable control rather than simple on-off operation. Fluid proportional valves can be controlled by electrical, electronic, or pneumatic input signals and are compatible with sensors, PLCs and control systems. Proper selection and functioning depend on correct sizing, materials of construction, fluid cleanliness, pressure ratings and control signal.

Operation
The proportional valve operates by receiving an electrical or pneumatic command signal. For electrically controlled versions, the proportional solenoid generates a magnetic field that moves an internal spool (or poppet/regulator element), changing the flow area. The magnitude of the input signal determines spool position and thus flow or pressure output. This enables intermediate positions between fully open and fully closed for precise regulation of hydraulic oil, air, water and other compatible fluids.

Applications

• Industrial automation: controlled motion of hydraulic and pneumatic actuators in automated machinery and robotics.
• Hydraulic machinery and mobile equipment: precise regulation of oil flow and pressure in construction equipment, material handling and heavy equipment.
• Production lines and OEM equipment: clamping force control, cylinder speed regulation, tooling movement and process control.
• Process industries: dosing, mixing, cooling, heating and circulation systems when materials and specifications are appropriate.
• Robotics: smooth motion and controlled force in hydraulic or pneumatic actuation systems.

Advantages

• Precise variable control of flow and pressure for smoother and more accurate machine operation.
• Compatibility with PLCs, sensors and electronic controllers for integration into automation systems.
• Smoother actuator movement and reduced shock by enabling intermediate valve positions.
• Flexible operation: single valve can operate at different levels according to control signals.
• Improved process consistency and potential energy savings with correct system design.

Disadvantages / Considerations

• Higher initial cost compared with simple on/off valves, including drivers and electronics.
• More complex control, requiring proper electronics, calibration and controller tuning.
• Sensitivity to contamination: contaminated fluids may cause sticking, unstable operation or premature wear.
• Troubleshooting can be more complex (valve, controller, wiring, sensors and system interactions).
• Heat generation can occur from throttling and continuous electrical operation; system design must consider dissipation.

Troubleshooting & Maintenance

• No response: check power supply, controller output, wiring, connectors, coil and input signal integrity.
• Low flow: verify valve sizing, supply pressure, filters, fluid viscosity, restrictions and pressure differential.
• Unstable flow: inspect for contamination, air in system, unstable supply pressure, electrical noise, grounding issues and controller tuning.
• Valve sticking: check for contamination, damaged seals, mechanical debris, temperature effects or wear; clean or replace components per manufacturer guidance.
• Incorrect pressure or actuator speed: verify pressure settings, sensor calibration, relief valves, signal scaling and controller parameters.
• Preventive maintenance: maintain filtration, check electrical connections, monitor pressure/temperature and validate valve response/calibration periodically.

Notes on Selection & Design

• Choose fluid compatibility (hydraulic oil, compressed air, water, coolant, gas) and appropriate seal/body materials for temperature and chemical conditions.
• Determine minimum, normal and peak flow and choose valve capacity to avoid oversizing (reduces precision) or undersizing (excessive pressure drop).
• Verify operating and spike pressures with adequate safety margins and confirm port size, thread and mounting requirements.
• Match control signal ranges (voltage/current) between valve, driver and controller; consider response time, hysteresis and need for closed-loop feedback for high-precision tasks.
• Plan filtration and avoid installing with unsupported piping or in orientations that create mechanical stress.

Caractéristiques / spécifications techniques

• Brand: Weilong
• Model Number: WL 9902
• Rated Voltage (V): DC12V or 24V
• Rated Power (W): 7.2W
• Work Mode: Air Control Valve
• Working Pressure (MPa): 0.2 MPa
• Airflow Rate: 0.1-2 L/minute
• Reset Time(s): 1 S On, 1S Off
• Service Life: 200 Thousand Times
• Certification: CE, ROHS, ISO9001
• Material: Superior Magnet Iron
• Lead Wire Length (mm): 200 MM
• Install Style: Screw
• Tolerance of Dimension: ± 0.1 MM
• Water-proof: None
• Insulation Class: B
• Hi-Pot Test: AC 750V 50/60Hz 2s
• Non-excitation Holding Force: 0
• Working Temperature: -10°C-90°C
• Duty Cycle: 1-100%
• Thread Depth (mm): /
• Payment Term: TT, or LC at Sight
• Sample Order: Yes.
• Warranty: 1 Year
• MOQ: 1000 pcs
• Supply Ability: 5000 pcs per week
• Delivery Time: 30 Days
• Port of Loading: Shenzhen