ToolnozaInputs and measurement basis
Enter required delivered liters, precharge and operating pressures as gauge bar, ambient absolute pressure and polytropic exponent. The calculator adds ambient pressure before applying the gas law. Use the same precharge temperature reference as operating conditions.
Required delivered fluid (L); Gas precharge (bar gauge); Minimum pressure (bar gauge); Maximum pressure (bar gauge); Ambient absolute pressure (bar); Polytropic exponent n (1–1.4).
Formula and calculation
Pabs = Pgauge + Pambient; V0 = ΔV/[(P0/Pmin)^(1/n) − (P0/Pmax)^(1/n)].
Estimate gas accumulator nominal volume for a required fluid delivery between minimum and maximum pressure.
Worked example
ΔV = 10 L; P0 = 90 bar(g); Pmin = 100 bar(g); Pmax = 200 bar(g); Pambient = 1 bar(a); n = 1 → V0 = 22.31 L.
How to interpret the result
The calculated nominal volume is the gas space at precharge, before hydraulic fluid enters. Delivered fluid is the difference between gas volumes at the minimum and maximum operating pressures.
The exponent represents the assumed thermal response: n = 1 is isothermal and n near 1.4 approximates rapid nitrogen compression. Actual charging and discharge may need different exponents and temperature corrections.
Assumptions and limits
Ideal gas-volume estimate only; 1 ≤ n ≤ 1.4. Requires precharge below minimum pressure. Does not check bladder compression ratio, discharge rate, temperature correction, real gas behavior or vessel rating. Final selection requires manufacturer sizing.
Frequently asked questions
Why add ambient pressure? The gas law uses absolute pressure. Applying it directly to gauge values gives an incorrect volume, especially at low pressure.