"Hans" wrote in message ...
I agree.

For a normal person it is almost impossible to understand all these
interesting topics when it is full of gallons, feets and psi's instead of
litres, meters and Pascals

That's a rather provincial notion don't you think?
That only "normal" people use SI units and you have to
be abnormal to use feet or gallons. Where's the love
of diversity? Where's the basic level of respect for
other cultures and other methods of doing things?