Hydrogen Trailer Return Calculator

Enter the trailer pressure when it was delivered and when it came back. The calculator gives the hydrogen used, in kilograms.

Trailer and readings

Optional
Optional
Pressure with every cylinder open

70 if not measured

70 if not measured

Nothing you enter here is sent or saved. The calculation runs in your browser and is gone when you close the page.

Hydrogen used

Enter the return pressure to see the hydrogen used.

Delivered
502.1 kg
Rated full capacity at 70 °F
502.1 kg

How it works

A reading in bar is converted to psig at 14.5038 psi per bar. The hydrogen factor, in SCF per cubic foot of water volume at 70 °F, is read from a table in 25 psi steps from 0 to 10,000 psig and interpolated in a straight line between steps. Above 10,000 psig the 10,000 psig value is used.

Gas in the trailer is the factor times the water volume times 530 ÷ (460 + gas temperature in °F), which is 1 at 70 °F. Hydrogen used is the gas at delivery minus the gas at return, and kilograms are SCF ÷ 423.3 unless you change it. Rated full capacity is the gas at the full fill pressure at 70 °F.

Sources: N.E. Bjork for 0 to 5,000 psig, and NBS Technical Note 1079 for 5,000 to 10,000 psig.