Hydraulic Reservoir Size Calculator

Inputs

Pump flow (Q)

Total pump flow returning to the tank.

L/min

Residence time (t)

Target oil residence time in the reservoir. Three minutes is a common screening start.

min

Usable oil fraction (f)

Fraction of total tank volume normally filled with usable oil, leaving air space above.

Default result

Usable oil volume

120,000cm³

Also computed

Nominal tank volume150,000cm³

Includes headspace above the normal oil level.

Tank turnovers per minute0.267

3 min residence target.

Method notes 3 notes

This is a residence-time sizing check: usable oil volume = pump flow × minutes in tank.
Final reservoir size also depends on heat load, return-line aeration, cylinder volume change, sloped bottoms, baffles, suction head and fluid expansion.
Use a smaller usable fraction when you need more headspace for foaming, expansion or sloshing.