Description
HD – SV/SL – Hydraulically Pilot Operated Check Valve
The HD – SV/SL – Hydraulically Pilot Operated Check Valve is an important part of hydraulic systems that provides directional flow control and safety in high-pressure applications. Its efficient pilot-operated mechanism makes the valve a combination of secure flow locking and flexibility of controlled reverse flow, which is indispensable in industrial and mobile hydraulics.
This valve is designed for high performance situations where pressure retention and control is essential. The HD – SV/SL valve, designed with an eye towards precision and durability, offers reliability in the most demanding conditions.
Key Features of HD – SV/SL Check Valve
- Check valve controlled by fluid
- For subplate mounting,Mounting pattern to DIN 24 340
- Subplate or screw threaded connection
- With or without leakage port
- With or without pre-opening
- Type with pre-opening,dampened decompression
- 4 opening pressures
- Porting pattern to Din 24 340 form A, ISO 4401 and CETOP-RP 121H3
Applications of Pilot Operated Check Valve
Due to its accurate control, safety, and flow control, the HD – SV/SL hydraulically pilot-operated check valve is applied in various industries. Common applications include:
- Hydraulic Presses: Holds the load in place during the time when the system is not working, so that it does not move unexpectedly.
- Lifting Equipment: It keeps hydraulic cylinders in their position unless a pilot signal is given.
- Injection Molding Machines: Controls locking of the mold and pressure uniform throughout injection.
- Construction Machinery: It holds the boom or arm in place safely in excavators, loaders and cranes.
- Agricultural Equipment: Found in implements and attachments to make sure that things are securely held and are controlled in their retraction.
- Machine Tools: Makes clamping systems stable and hold pressure if necessary.
- Material Handling Equipment: Makes forklifts, lifts, and stackers safe to use.
- Marine and Offshore Systems: Assists to maintain stability and control on ships’ decks.
- Hydraulic Power Units (HPUs): Applied in systems used for controlling pressure and those that load accumulators.
- Wind and Renewable Energy Systems: Applied in pitch controlling and stop brakes system.
In all these situations, the HD – SV/SL valve makes sure the system is safe and works accurately.
Operating Principle of Pilot Operated Check Valve
The HD – SV/SL valve acts as a hydraulically pilot-operated check valve that has the functions of a standard check valve and an externally controllable bypass.
- Flow Direction and Check Action
In normal operation, fluid flows freely in one direction (inlet to outlet).
In the opposite direction, the valve stops flow — no backflow or unwanted movement.
- Pilot Operation (Reverse Flow Enablement)
The application of a pilot pressure to the specified pilot port causes the internal pilot piston to move the poppet or spool mechanism.
This action skips the check mechanism, allowing fluid to move in reverse – either making the cylinder retract or running the reverse circuit.
- Load Holding Functionality
As soon as pilot pressure is taken off, the valve quickly closes and stops the flow.
Therefore, the valve prevents vertical or suspended loads from moving erratically when the system has leaks or low pressure.
- Internal vs External Pilot
There are those that draw their pilot pressure from the line and others that use external pilot lines thus providing more options for system setup and control.
The valve does not only prevent the undesirable backflow but also provides precise and timed reverse movement as required, which guarantees safe load control and smooth movement.
Pilot operated check valves types
The HD- SV/SL range has a number of types and configurations to cater for different industrial needs. The following are the major types depending on port configuration, pilot design, and mounting.
- Single Pilot Operated Check Valve (SV)
Permits flow in one direction and opens in reverse direction with pilot pressure.
Suitable for Single-acting cylinders or circuits that need one way control with reverse override.
- Double Pilot Operated Check Valve (SL)
Offers controlled check action in both directions.
Applied in double-acting cylinder applications where holding is necessary in both directions.
Commonly in synchronized motion circuits.
- Cartridge Type
Installed in standard cavities in valve blocks or manifolds.
Offers small and economical installation in custom hydraulic systems.
- Inline Type
Stand alone valves with threaded ports for direct pipeline installation.
Suitable for retrofit or external mounting applications.
- Subplate Mounting Type
Mounted on normal subplates for ease of service and modularity.
Frequently employed with the directional valves.
- External vs Internal Pilot Control
External Pilot: Allows separate control line to provide pilot pressure.
Internal Pilot: Relieves the system line itself for simplicity.
- With or Without Leakage Path
Some of the variants provide a controlled leakage path to help in slow movement or controlled bleeding of pressure.
Others are leak-proof, offering tight shut-off for those applications that need to be sealed completely.
There are some advantages of each type of HD – SV/SL valve, and engineers can choose the best option for load requirements, safety aspects, and flow dynamics.
Why HD – SV/SL Check Valves?
- Reliable Load Holding: Prevents accidental drop of loads because of leaks or pressure loss.
- Optimized Safety: Protects hydraulic actuators when not in use or power failure.
- Versatile Configurations: Comes in different sizes, pressures, and mounting types.
- Improved System Efficiency: Energy loss is minimized and overall control is improved.
- Durable and Long-Lasting: Engineered for high cycle operations and hostile environments
The HD – SV/SL – Hydraulically Pilot Operated Check Valve is an important component of the modern hydraulic systems where safety, precision, and control are paramount. Its pilot operation mechanism offers flexibility without sacrificing on the check valve functionality.
If you are working with heavy industrial presses, construction machinery, or precision automation, the HD – SV/SL series will guarantee reliable performance, excellent flow control, and system protection.
For those industries looking for high-quality, leak-proof, and customizable check valve solutions — the HD – SV/SL series is the reliable option.
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