Are you building a new hydraulic power unit, modernizing a press, or perhaps designing arms for a custom machine? Sooner or later, you'll face a crucial decision: which spool valve to use? The two most common plate standards on the market are CETOP 03 (NG6) and CETOP 05 (NG10) . Although at first glance they differ only in size, a poor choice can result in power loss, system overheating, or even pump damage.
In this article, BRhydraulic experts explain the differences between these two standards and how to perfectly match the valve size to the performance of your installation.
1. Let's decipher the terminology: NG and CETOP
Before we get into the parameters, let's clear up some terms that often cause confusion:
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NG (Nominal Size): Specifies the internal diameter of the flow channels in millimeters. NG6 is 6 mm channels and NG10 is 10 mm channels.
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CETOP / ISO 4401: This is an international standard that specifies the mounting bolt spacing and port layout (P, T, A, B) on the subplate.
In industry practice, these names are used interchangeably:
👉 CETOP 03 = NG6 (most often 4WE6 valve series)
👉 CETOP 05 = NG10 (most often 4WE10 valve series)
2. Main selection criterion: Oil flow (l/min)
The solenoid valve size should always be selected based on the maximum capacity of the hydraulic pump , not by eye. A valve that is too small will act as a bottleneck.
When to choose the CETOP 03 (NG6) solenoid valve?
This is a workhorse for light and medium-duty hydraulics. With smaller channels (6 mm), it's designed to handle systems with a pump flow rate of 0 to 60 l/min (with peaks of up to 80 l/min during short-term operation).
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Application: Smaller workshop presses, front loaders (Tur), trailers, agricultural machinery, smaller CNC machine tools.
When do you need to switch to the CETOP 05 (NG10) solenoid valve?
If your machine requires fast movements of powerful actuators and the pump generates flows of 80 to 120 l/min , a smaller valve will simply "choke." The wider channels (10 mm) in CETOP 05 valves allow this large volume of oil to flow freely.
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Applications: Industrial press brakes, plastic injection molding machines, heavy hydraulic power units, extensive production lines.
3. What happens if you choose a valve that is too small? (Effects of throttling)
This is the most common mistake made by designers looking to save money (NG6 valves are cheaper than NG10). If you connect a CETOP 03 solenoid valve to a pump delivering 100 l/min, you will experience drastic flow throttling .
Forcing 100 liters of oil through 6-millimeter holes creates enormous resistance (pressure drop, known as $\Delta p$ ). The energy that was supposed to go into the actuator is converted into heat. The result? The hydraulic oil literally begins to boil , the seals harden and crack, the pump howls, and the machine loses power and slows down.
4. Assembly differences: Are the connection plates interchangeable?
No. These are completely different assembly standards.
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The CETOP 03 valve is mounted on the division plate using four M5 screws.
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The CETOP 05 valve is significantly larger and heavier. It requires a larger subplate and is mounted with four thicker M6 screws (sometimes with an additional locating pin).
Additionally, due to the more powerful hydrodynamic forces acting inside the NG10 valve, it requires larger and more powerful solenoid coils to move the spool.
Summary
Choosing between a CETOP 03 and CETOP 05 manifold is a matter of math, not guesswork. Check your pump's nameplate:
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Flow up to 60-80 l/min ➡️ Select CETOP 03 (NG6) solenoid valves
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Flow 80-120 l/min ➡️ Select CETOP 05 (NG10) solenoid valves
Need a complete valve block with manifold plates? At BRhydraulic, you'll find manifolds and accessories in both standard versions, with 12V, 24V, and 230V coils.