SW Series Solenoid Operated Check Valves

Overview

The SW20P and SW30P Series are solenoid-operated pilot check valves (also known as electromagnetic check valves or solenoid-controlled non-return valves) designed for precise load holding and controlled release in hydraulic systems. Available in SW20P (20mm line size) and SW30P (30mm line size) configurations, these valves combine the reliable blocking function of a traditional check valve with the convenience of electrical control for load lowering and circuit isolation.

Key Features

Primary Functions

1. Load Holding — Blocks hydraulic fluid flow in one direction to securely hold loads in position without drift

2. Controlled Release — Solenoid activation opens pilot passage to allow controlled reverse flow for load lowering

3. System Isolation — Electrically isolates hydraulic circuits for maintenance or emergency stop functions

4. Safety Protection — Prevents uncontrolled load descent in case of hose failure or pump shutdown

Detailed Application Scenarios

1. Hydraulic Presses & Stamping Equipment

• Function: Holds press ram in elevated position during die changes and maintenance

• Operation:

  • Check valve function prevents ram descent when pump stops

  • Solenoid activation allows controlled lowering via flow control valve

• Safety: Critical for personnel safety during mold setup; prevents accidental ram drop due to valve failure

• Typical Setup: SW30P for main ram (high flow); SW20P for cushion or ejector cylinders

2. Mobile Elevating Work Platforms (MEWPs)

• Applications:

  • Scissor Lifts: Platform elevation holding and controlled descent

  • Boom Lifts: Telescopic boom extension holding

  • Aerial Platforms: Basket leveling and rotation control

• Safety Compliance: Meets ANSI/SIA A92 and EN 280 standards for load holding devices

• Benefit: Solenoid-controlled lowering allows smooth, controlled platform descent independent of engine speed

3. Injection Molding Machines

• Function:

  • Mold clamping force maintenance during injection

  • Core pull and slide retention

  • Ejector plate position holding

• Precision: Zero leakage ensures consistent clamping force for part quality; solenoid release enables precise mold opening sequence

• Energy Efficiency: Allows pump unloading while maintaining full clamping force

4. Material Handling & Lifting Equipment

• Applications:

  • Forklifts: Mast tilt and fork positioning hold

  • Overhead Cranes: Hoist load holding and controlled lowering

  • Stackers: Lift carriage position maintenance

  • Dock Levelers: Platform height retention

• Advantage: Prevents load drift during transport; emergency lowering capability via solenoid activation

5. Construction & Mining Machinery

• Applications:

  • Excavators: Boom and arm position holding during engine-off operation

  • Dump Trucks: Body hold during transport; controlled tipping

  • Concrete Pumps: Boom section holding and controlled positioning

  • Drilling Rigs: Mast raising and feed hold

• Durability: Robust construction withstands shock loads and contaminated hydraulic fluid common in construction environments

6. Machine Tool Hydraulics

• Function:

  • Workpiece clamping force maintenance during machining

  • Counterbalance for vertical axis slides

  • Tailstock and quill position holding

• Precision: Maintains clamping force without pump operation; reduces heat generation and energy consumption

7. Renewable Energy Systems

• Wind Turbines:

  • Rotor brake holding during maintenance

  • Pitch cylinder position lock for emergency feathering

  • Yaw brake release control

• Solar Tracking: Hydraulic actuator holding for panel positioning systems

8. Marine & Offshore Equipment

• Applications:

  • Deck Cranes: Load holding during vessel motion

  • Hatch Covers: Secured closure during sea transit

  • Anchor Windlasses: Chain and anchor holding

  • Steering Gear: Rudder position lock

• Corrosion Resistance: Optional marine-grade coatings and stainless steel components available

Technical Advantages

• Zero Leakage Design: Precision-ground poppet and seat provide metal-to-metal sealing with virtually no internal leakage

• Pilot-Operated Release: Low solenoid force requirement due to pilot ratio; allows use of standard solenoid coils

• Fast Response: Solenoid activation opens pilot passage within 30-50 ms for immediate load release

• Bi-Directional Flow: Free flow in forward direction with minimal pressure drop (typically < 1 bar at rated flow)

• Manual Override: Optional manual release screw for emergency operation without electrical power

• Compact Integration: Cartridge versions install directly into manifold blocks; inline versions for pipeline mounting

Installation & Maintenance Notes

• Mounting Orientation: Preferably vertical with solenoid upward to prevent air trapping; horizontal mounting acceptable with proper bleeding

• Pilot Line Filtration: Critical to maintain ISO 4406 18/16/13 cleanliness to prevent pilot orifice blockage

• Back Pressure Consideration: Tank line back pressure affects pilot operation; ensure tank line pressure remains below 20 bar

• Solenoid Duty Cycle: Continuous duty solenoids recommended for applications requiring extended holding periods

• Pressure Spikes: Install dampening orifices if system experiences severe pressure spikes to protect pilot stage

Conclusion

The SW20P and SW30P Series solenoid-operated check valves provide the critical combination of secure load holding and controlled electrical release demanded by modern hydraulic systems. Whether ensuring operator safety in aerial work platforms, maintaining precision in injection molding, or securing heavy loads in construction equipment, these valves deliver reliable performance where uncontrolled motion could result in equipment damage or personnel injury. Their robust design, fast response, and flexible mounting options make them the preferred choice for hydraulic system designers prioritizing both safety and operational efficiency.