The same nominal valve size can have different usable flow ranges depending on its spool and flow path. A maximum flow headline is not enough to predict cylinder speed, available force or heat generation in your circuit.
Calculate the flow for each movement
For a cylinder, use the piston area for extension and the annular area for retraction. Multiply the active area by the required speed, using consistent units. Return flow can exceed pump flow during retraction, so evaluate both the supply and return paths.
Read the relevant curve
Use the manufacturer's pressure-drop curve for the chosen spool and connection, such as P to A or B to T. Check the fluid viscosity and test conditions. Add the losses of connected fittings, hoses and other valves rather than treating the directional valve in isolation.
Compare the operating points
A larger body may reduce loss but increase size, cost or pilot requirements. Record pressure drop at normal and peak flow, then verify operating limits and switching capability. Treat a calculated flow as a design input, not proof that any similarly sized valve is suitable.
Practical checklist
- Calculate extension and retraction return flows.
- Identify the exact spool's pressure-drop curves.
- Allow for simultaneous functions and return-line restrictions.
Discuss your application
Explore related hydraulic products, or send JIUDING your model code and application details. Include the circuit drawing and the operating conditions relevant to the checks above so the required configuration can be reviewed.
Cover image: AI-generated editorial illustration, not a model-specific product drawing or a photograph of a JIUDING facility.
