On the other hand, a gasoline powered water pump with a 2" pipe outlet (50 mm) might be able to do the trick, if they have them handy, and if they have a way to pump this water into the system. Power wise, they need about 25 kw engines to pump this water, or about 35 hp ones.

Is this power needed in excess of internal pressure?so would those pumps be able to pump against the Nominal 75 atmosphere internal system pressure?

Any idiot can face a crisis - it's day to day living that wears you out.