Tank, Vessel & Pressure Equipment Fabrication worked example

Pressure Test Water Volume at 61% fill and recovery efficiency: a worked example

Suppose fill and recovery efficiency falls to 61%. This page works the full calculation at that level so you can see exactly which result moves and by how much. The Pressure Test Water Volume metric tells a tank and pressure-vessel shop how much water to stage before a hydrostatic test so the vessel can be filled, pressurized, and topped off without running the source dry mid-test.

The inputs for this scenario

  • Internal volume to fill for hydrostatic test: 500 gal (held at the documented default)
  • Water allowance per gallon of vessel volume: 0.08 ratio (held at the documented default)
  • Fill and recovery efficiency: 61 % (the input this scenario stresses; the baseline uses 85)

Working through the calculation

  • The calculation starts from the formula this tool documents: Required pressure test water volume = covered amount × use per unit ÷ transfer efficiency.
  • Required quantity works out to 65.57 psi at these inputs, and this is the headline figure for the scenario.
  • Theoretical amount works out to 40 psi at these inputs.
  • Loss allowance works out to 25.57 psi at these inputs.
  • Efficiency works out to 61 % at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where fill and recovery efficiency sits at 85% and the headline result is 47.06 psi, this scenario comes in 39.34% above the baseline at 65.57 psi.
  • It computes the total water volume you must supply to hydrostatically fill and pressurize a vessel, grossed up for fill and recovery losses. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Required quantity: 65.57 psi (headline result)
  • Theoretical amount: 40 psi
  • Loss allowance: 25.57 psi
  • Efficiency: 61 %

Run it with your numbers

  • To rerun this with your own numbers, open the live Pressure Test Water Volume calculator, set fill and recovery efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.