Want someone to check this calculation? The request is sent with the data and results already filled in: just add a description of the problem.
Ask for a consultationIndicative results, provided for preliminary estimation. They do not replace the design and verification of the real case by a qualified professional.
How to use it
Hydraulic cylinder. With bore, rod and pressure you get the push and pull forces. Adding the pump flow rate gives the extension and retraction speeds and the hydraulic power; entering the required force gives the pressure needed to develop it.
Pipe losses. Choose the fluid, flow rate and inner diameter, then length, material, height difference and the sum of the local loss coefficients. The tool calculates velocity, Reynolds number, friction factor and the pressure the pump must supply to overcome the losses.
Formulas used
The Swamee–Jain formula approximates the Colebrook equation to within about 1% in turbulent flow. In the transition zone (Re between 2300 and 4000) the friction factor is uncertain and the result should be taken with a margin.
Where a real design is needed
The calculation of a single line doesn't account for pressure peaks, water hammer, oil heating, rod buckling and pressure drops across valves and filters, which often weigh more than the pipe. For sizing a complete circuit, a power unit or a compressed air distribution network, you'll find the service under plants and energy and automation and robotics.
FAQ
Why is the pull force lower than the push force?
When pulling, the pressure acts on the annular area, i.e. the piston area minus the rod area. That's why, at the same pressure, the pull force is lower and the retraction speed higher.
What velocity should I choose for oil in the pipes?
Reference values: suction 0.5–1.2 m/s, return 2–3 m/s, pressure line 3–6 m/s depending on pressure. Higher velocities increase losses, noise and heating.
How do I estimate the sum of the coefficients ΣK?
You add up the coefficients of the individual elements: a 90° bend is about 0.3–0.9 depending on the radius, an open ball valve about 0.05, a tee in branch flow about 1.0–1.5, an outlet into a tank 1. Exact values are in the component catalogues.
Does the calculation also apply to compressed air?
No: air is compressible and its density changes along the line. Compressed air networks need dedicated formulas, especially on long runs or with large pressure drops.