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Plant Engineering Calculator

Updated Sep 18, 2026

Compressed Air Receiver Fill Time Calculator — Volume, Pressure Band & Compressor Flow

Estimate receiver pressurization time from vessel volume, starting and final absolute pressures and compressor free-air delivery using an isothermal ideal-gas balance.

Live calculationWorking shownPrivate in browser

Inputs

Results

Free-air equivalent required 4.93 m³
Ideal fill time 4.93 min
Ideal fill time 296 s
Average charging rate 1.00 m³/min FAD
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

t=V×(P2abs−P1abs)/(Qfree×Patm).

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Absolute pressures: P₁ = 2.000 + 1.01325 = 3.01325 bar abs; P₂ = 7.000 + 1.01325 = 8.01325 bar abs.
  2. 2.Pressure rise ΔP = 8.01325 − 3.01325 = 5.00000 bar.
  3. 3.Free-air equivalent = 1.0000 × 5.00000 ÷ 1.01325 = 4.93462 m³.
  4. 4.Ideal fill time = 4.93462 ÷ 1.0000 = 4.93462 min = 296.1 s.

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

A 1 m³ receiver charged from 2 to 7 bar g at 1 m³/min FAD needs about 4.93 m³ free-air equivalent, or about 4.93 ideal minutes, at 1.01325 bar atmospheric reference.

Assumptions and limits

  • Assumes approximately isothermal ideal-gas storage and constant free-air delivery.
  • Real compressor capacity changes with pressure; account for leakage, aftercooling and controls for commissioning predictions.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Why are gauge pressures converted with atmospheric pressure?

Stored gas mass follows absolute pressure. The required free-air equivalent is V(P₂abs−P₁abs)/Patm; using gauge pressure in the gas-law ratio without the absolute reference is inconsistent.

Why can actual receiver fill time differ from this result?

The model assumes isothermal ideal-gas storage and constant free-air delivery. Real compressor FAD can fall with discharge pressure, and leakage, aftercooling, control deadband and temperature rise all change commissioning time.

Can this calculator size a pressure vessel?

No. It only estimates charging air and time. Receiver mechanical design, relief protection, inspection and code compliance must follow the applicable pressure-vessel rules and manufacturer data.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

compressed air storage capacityair receiver sizingair compressor cfm
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.