Hydraulic Solenoid Valves 4WEH25 (NG25 / CETOP 8)

Extreme performance for heavy industry. 4WEH25 directional control valves are two-stage, electrohydraulically operated valves designed to handle high oil flows (up to 700 l/min ). ISO 4401-08 (CETOP 8) mounting standards provide a reliable solution for presses, metallurgy, and large hydraulic systems. Operating pressures up to 350 bar.
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4WEH25 Splitters – Pilot Control Power (NG25)

In this category, we offer the largest standard solenoid valves available in common use – nominal size NG25 (ISO designation: size 08, CETOP designation: size 8). These are heavy-duty designs, designed for the harshest environments where precise control of enormous hydraulic power is required.

Two-Stage Design (Pilot + Main Stage)

Like the smaller NG16 models, the 4WEH25 valve operates in a two-stage system:

  1. Pilot Control: A standard NG6 (CETOP 3) solenoid valve sits atop the body. Its function is to direct a small amount of pressurized oil to the face of the main spool.
  2. Main Stage: The massive lower block houses a large 25mm diameter slide valve that opens the main flow to the pump and actuator. This allows a small electric solenoid to control several hundred horsepower of flow.

Technical Parameters and Configuration

The offered valves are fully interchangeable with products of the following brands: Bosch Rexroth, Vickers, Parker and Atos (series 4WEH 25...).

  • Maximum flow: Up to 650 - 700 l/min (depending on oil viscosity and pressure).
  • Pressure: Up to 350 bar in channels P, A, B and up to 250 bar in channel T (depending on drainage option).
  • Pilot Control (X and Y Channels): This is a critical parameter. 4WEH25 valves have control channels in the mounting surface. Supply (X): Can be Internal (from P channel) or External (from a separate control system). Drain (Y): Can be Internal (to T) or External (separately to the tank). Tip: Most of our valves allow for easy, mechanical change of X/Y configuration by unscrewing/screwing plugs inside the body (check the manual!).

Overdrive time

Due to the heavy spool mass and hydraulic control, these valves feature an optional override time adjustment . This choke is located between the pilot and main valve to eliminate water hammer when switching such high flows.

Application

Where can you find 4WEH25 valves?

  • Large-scale hydraulic presses (for metal, rubber, plastics).
  • Metallurgy and rolling mills.
  • Marine hydraulics (rudder control, winches).
  • Mining equipment.

FAQ: Hydraulic Solenoid Valves 4WEH25 (NG25 / CETOP 8)
1. What systems is the 4WEH25 (CETOP 8) solenoid valve intended for?

The 4WEH25 series are powerful electrohydraulic distributors designed to handle huge volumes of oil.

  • Maximum flow: These valves easily handle flows of 450 to even 650 l/min (depending on the slide pattern).
  • Applications: They are the foundation of heavy industry. You'll find them in giant hydraulic presses (with thousands of tons of pressure), large-scale injection molding machines, heavy mining machinery, metallurgy, and marine systems.
2. What is the difference between the 4WEH25 (NG25) valve and the smaller 4WEH16 (NG16)?

The main difference is the physical size of the body, assembly standard and throughput.

  • 4WEH16 (CETOP 7): Handles flows up to approx. 300 l/min.
  • 4WEH25 (CETOP 8): Features significantly wider internal passages, allowing for almost twice the oil flow (up to 650 l/min) without the risk of choking or overheating. It also requires a significantly larger subplate to the ISO 4401-08 (CETOP 8) standard.
3. How to solve the problem of loud water hammer when switching the 4WEH25 valve?

At flow rates of several hundred liters per minute, the sudden movement of the huge slide in the main valve can cause a water hammer (a pressure surge that destroys pumps, pipes and seals).
The solution is to use a throttle plate (time delay) , mounted as a "sandwich" between the small pilot valve (top) and the main body of the 4WEH25 valve (bottom). This throttle allows for smooth adjustment of the main spool travel time (up to several seconds), ensuring a smooth, jerk-free start and stop of powerful actuators. At BRhydraulic, we can advise you on how to properly configure such a setup.
4. Internal or external control? How do I set the pilot power (X) and return (Y) in the NG25 series?

This is a key aspect of the 4WEH valves' proper operation. The small solenoid valve at the top requires pressure to move the lower slider.

  • Internal Pilot / Internal Drain: Pilot oil is drawn directly from the main supply channel (P) and returned through the main return channel (T). This is the simplest solution, but requires a minimum system pressure (approximately 10 bar) at all times.
  • External Pilot / External Drain: Oil is supplied through an independent channel (X) from a separate, small control pump, and returns through an independent channel (Y) directly to the tank. This solution is recommended in heavy industry, as it makes the valve operation independent of pressure fluctuations and surges in the main machine operating system.
    Tip: Changing the configuration from internal to external can be done by screwing in or unscrewing the threaded plugs (plugs) inside the channels of the 4WEH25 valve.
5. What slider diagrams for 4WEH25 can I find in BRhydraulic?

We supply a full range of sliders for industrial systems. The most frequently ordered ones include:

  • Slider E: Standard closed slider (ports P, T, A, B closed in neutral position). Ideal for positioning cylinders in presses.
  • Slider G: Pump relief (connection P to T), with blocked actuator outputs (A, B closed).
  • J and H sliders: Designed for systems where the actuator or hydraulic motor must be able to move freely under the influence of external forces after the power is turned off.

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