Absolute-pressure single-exponent ideal-gas screening
Documented Accumulator Gas-Volume Screening Calculator
Calculate the ideal precharge gas volume and gas states for one documented liquid-delivery cycle. All three pressures must be absolute and temperature-normalized for the selected calculation basis.
Documented ideal-gas screening result
Implemented single-exponent model
V1 = V0(p0/p1)^(1/n)
V2 = V0(p0/p2)^(1/n)
ΔV = V1−V2
V0 = ΔV / [(p0/p1)^(1/n) − (p0/p2)^(1/n)]
Only ratios of pressures appear, but every pressure must be absolute. A gauge value must first be converted with a documented atmospheric/reference pressure in the same unit. The page never assumes that bar(g) equals bar(a) or that a fixed atmospheric offset is correct for every site/reference.
Process exponent and temperature
Isothermal operation uses n=1. A polytropic value, including 1.4 for a justified rapid nitrogen idealization, must be entered with its product/cycle source. This page does not decide n from an arbitrary time threshold and does not apply precharge-temperature or real-gas corrections.
Manufacturer reference and published example
The HYDAC accumulator catalogue publishes the same ideal-gas equation, distinguishes isothermal/polytropic/adiabatic cases, requires temperature and real-gas corrections, and gives an example with p0=1245 psi, p1=1500 psi, p2=3000 psi, ΔV=1.35 US gal and n=1.4. The displayed equation gives V0=3.949314 US gal, reproducing the catalogue’s rounded ideal result of 3.95 US gal before its 1.16 real-gas correction and nominal-size selection. The Parker HY10-1630/US sizing guide explicitly defines its sizing pressures in PSIA, uses application/time/temperature-dependent gas coefficients and warns that temperature variation affects precharge.
Standards boundary
ISO 4413:2010, edition 3, Published and confirmed in 2021, specifies general rules and safety requirements for hydraulic systems. Its public abstract does not establish this sizing equation, exponent or precharge percentage; this page therefore does not call the arithmetic an ISO formula or claim ISO 4413 compliance. The inventory token “ISO 70” was a false positive caused by a former numeric preset beginning with 70, not a cited standard.
Why the former page was changed
The former inputs were merely labelled “bar,” inviting gauge-pressure entry into an absolute-pressure gas law. It silently chose n=1 or 1.4 from broad speed labels, published unsupported one-minute thresholds and universal 90/95% precharge rules, inserted presets/defaults and labelled the ideal V0 as the required accumulator volume without real-gas, temperature, product or reserve corrections.
Stored-energy hazard: this result is not authorization to select, charge, isolate or service an accumulator. Follow the exact manufacturer procedure and applicable law/standard. Parker’s guide states that accumulator circuits should automatically unload stored pressure when machinery shuts down. Verify rated pressure/temperature, compatible gas and elastomers, isolation, relief, discharge control, inspection and trained-personnel requirements.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
