I take it that your city doesn't maintain and test the hydrants where you live?
Hydrant flushing and hydrant testing are different, but it's usually if you are going to flush, you might as well put a pitot on it.
You will need to know your water main size, which lines are looped, which ones are dead headed and such to accurately gauge hydrant pressure.
Are you sure you don't have a water superintendent that can help?
TCSS.
Art