Jean-Christophe Duc (asker) Sep 28, 2021:

@all thanks, I have asked for clarification from the client, but it will take time

Tony M Sep 25, 2021:

@ Daryo As Florence has already suggested; but as I pointed out, the use of '+' in this way is common in FR, but less so in EN (unless referring to a number of things) I'm still convinced that, in the context of pumps '+ve' or 'positive' pressure is more plausible.

Daryo Sep 25, 2021:

Could it be "additional pressure"?

Assuming that there is any indication in the ST as to in relation to what this pressure would be "additional", and that there is somewhere a numerical value for this "+ pressure".

Tony M Sep 23, 2021:

@ Asker In most contexts, "+ pressure" simply means 'positive pressure' — i.e. the opposite of 'negative pressure', 'depression', or 'suction/vacuum'.
However, I confess I don't quite see how that fits within your context as given here...