Απλά οι μονάδες. Τα λίτρα τα μεταφράζεις ή όχι ανάλογα με το τι κάνεις στο υπόλοιπο κείμενο.
Είναι λίγο δύσκολο να φανταστείς μέγεθος με τέτοιες μονάδες, αλλά κοίτα πχ. εδώ:

http://www.hse.gov.uk/pubns/indg178.pdf
The following pressurised systems are not likely to require a written scheme of
examination:
an office hot water urn (for making tea etc);
■ a pneumatic cylinder in a compressed air system;
■ a handheld tool;
■ a combustion engine cooling system;
■ a portable compressed air receiver and the associated pipework, where the
■ product of the pressure in bars multiplied by the internal capacity in litres of the
receiver is less than 250 bar litres; and a portable LPG cylinder.