Four questions, in this order: what the valve must do, how it is mounted, what voltage the coil has (if it is electric) and what flow and pressure it will see.
1. What it must do
| You want to… | Valve | In our shop |
|---|---|---|
| Choose the direction of movement of a cylinder or a motor | Directional valve | Cetop 3 (NG6), Cetop 5 (NG10), Monoblock valves |
| Limit the maximum pressure and protect the circuit against overpressure | Pressure relief valve, fitted in parallel | Relief valves |
| Set the speed | Flow control valve or restrictor | Flow control valves, Restrictors |
| Let oil through in one direction and block it in the other; lock a cylinder | Check valve, simple or pilot-operated | Check valves |
| Control lowering and hold a suspended load | Overcentre (counterbalance) valve | Overcentre valves |
| Bring in a second actuator only when the pressure reaches the set value | Sequence valve | Sequence valves |
| Split the flow between two branches | Flow divider | Flow dividers |
Restrictor or flow control valve? A simple restrictor depends on pressure and temperature: if the load changes, the speed changes. A pressure-compensated flow control valve keeps the speed steady even when the load varies.
2. How it is mounted
- Subplate mounted (Cetop). CETOP 3, NG6, ISO 4401-03 and NFPA D03 are different names for the same mounting pattern: valves with this pattern fit the same subplate, whatever the brand. In our shop: Cetop 3 (NG6) and Cetop 5 (NG10).
- Cartridge. Screwed into a cavity in a manifold; chosen by cavity (for example CAV 08 or CAV 10) and pressure range. In our shop: NEM cartridge valves and Eurofluid manifolds.
- In-line. Fitted directly into the pipe or hose, by thread. See the guide "BSP and NPT threads" to identify the thread.
3. The coil (solenoid valves)
- Check the voltage and whether it is DC or AC. On the Duplomatic DS5, for example, D12 and D24 are 12 V and 24 V DC; A230 is 230 V 50 Hz AC.
- Versions D00 and A00 come without coils; coils are ordered separately. See Coils and Connectors.
- Got the right valve but with a different voltage? Often you only need to change the coil: contact us.
4. Spool, flow and pressure
- Spool (symbol). It defines what happens in each position: closed centre, open centre, tandem… The page NG6 / Cetop 3 valve equivalences shows the Duplomatic spool and the matching Vickers, Rexroth, Parker and Atos spools.
- Watch out for tandem spools (P connected to T in the centre): the solenoid sides are swapped compared with the other spools. When replacing one, check the a/b electrical connection.
- Flow. To size the cylinder, the cylinder calculator gives force and speed. On a cylinder, the flow through the directional valve is different on the extend and retract strokes, because of the area difference of the cylinder: choose the valve for the larger flow.
- Pressure. Check the maximum pressure on ports P, A and B and also the permitted pressure on T (return): it is a separate value in the catalogue and, on the Vickers DG4V-3 for example, it changes with the version and the coil type.
Got another brand's reference?
Type the full Vickers, Rexroth, Parker or Argo Hytos reference into the shop search: the equivalent item we have appears, marked "Equivalent to the code searched". If nothing comes up, send us the reference.
Sources
- Olaer, technical manual for hydraulic systems.
- Catalogues: Parker D1VW, Vickers DG4V-3, Duplomatic DS3 and DS5.
- Hidro Orfão practice.