Cryogenic gases are delivered liquid but consumed gaseous – and between those two worlds lies a factor of several hundred. The Cryogenic Liquid Calculator (LN₂, LO₂, LAr: Liquid ↔ Gas) converts LN₂, LO₂, LAr, LHe and LH₂ between litres, kilograms and standard cubic metres.
The three quantity measures
They are linked by two material properties: the density of the liquid at its boiling point (LN₂: 0.808 kg/l at −195.8 °C) and the standard density of the gas (N₂: 1.25 kg/Nm³). From these follows the famous expansion ratio: one litre of liquid nitrogen becomes around 646 standard litres of gas – with helium it is even about 700, with argon 780.
Step by step
- Select the gas: nitrogen, oxygen, argon, helium or hydrogen
- Enter the quantity: in litres of liquid, kilograms or Nm³ – the calculator always returns all three
- Specify the withdrawal rate (optional): in Nm³/h for the range calculation
- Read the result: mass, gas volume, cylinder equivalent and holding time
Worked example
100 l of liquid nitrogen: 100 × 0.808 = 80.8 kg, which is 80.8 ÷ 1.25 = 64.6 Nm³ of gas – as much as roughly 6.5 classic 50 l cylinders at 200 bar. At a withdrawal of 2 Nm³/h, the supply lasts a calculated 32 hours.
What the calculation does not capture
Cryogenic tanks constantly lose gas through heat ingress: typical boil-off losses are 0.3–3% per day depending on tank size and condition – over longer standing times this eats noticeably into the range. Also, the cylinder equivalence is calculated ideally; real 200 bar cylinders contain somewhat less due to real gas behaviour. For order planning, use your gas supplier's figures – but the orders of magnitude from the calculator are right for all common estimates.
