Cray91

I think that the only thing it would do it account for any system leaks. Because the system is pressureized the housing is almost at the same psi as the IM. The difference in time would be too minute to even calculate.

If there was a leak in one of your pipes though, the line comming off the IM would "compensate" for that. So it is a way to take small leaks that out of the equation.