KEVOS® MAKEOS · Hydraulics
Hydraulic Accumulator Size
What gas-charged accumulator size delivers this volume between the working pressures?
Nominal gas volume of a bladder or piston accumulator to deliver a required oil volume between minimum and maximum working pressures, for isothermal or adiabatic gas behaviour.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Oil volume to deliver | L | Oil volume needed between maximum and minimum pressure. |
| Gas precharge pressure (gauge) | bar | Nitrogen precharge (often about 90% of the minimum working pressure). |
| Minimum working pressure (gauge) | bar | Lowest pressure at which the system still works. |
| Maximum working pressure (gauge) | bar | Highest working pressure (relief or pump cut-out). |
| Polytropic exponent | 1.0 for slow (isothermal) cycles over several minutes; 1.4 for fast (adiabatic) discharges in seconds. |
Method and formulas
- Absolute pressures: P = gauge + 1.013 bar.
- V₀ = ΔV ÷ ((P₀ ÷ P₁)^(1/n) − (P₀ ÷ P₂)^(1/n)).
- Gas volume at a pressure = V₀ (P₀ ÷ P)^(1/n).
- Example: 2 L between 100 and 200 bar with 90 bar precharge needs about 5.5488 L of accumulator.
Limitations
- Ideal gas; real nitrogen deviates at high pressure, so allow a margin.
- Temperature changes between charging and operating alter the precharge.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size an accumulator for emergency or peak flow
- Check the precharge pressure
- Compare slow and fast discharge
Who it is for
- Hydraulic and process engineers
- Maintenance engineers
- Design engineers
What you get
- Required nominal gas volume
- Gas volumes at each pressure
- Precharge ratio
Interpreting the result
- Choose the next larger standard size; pressure vessels must comply with your pressure equipment regulations.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 352–368. Topic reference; no source tables or recommended settings are reproduced.
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