|One common source of disagreement between operators/engineers
and flowmeter manufacturers is based on a disparity between what pumps
can supposedly do and what they really do. For some apparently mysterious
reason a flowmeter will measure less flow in a system then was expected
based on the capacity of a series of pumps running in series.
The fact is, despite the apparent logic, that if one 300GPM
pump produces 300 GPM, it does not follow that two 300gpm pumps will produce
600 GPM or three 300 GPM pumps will produce 900 GPM. Reality is more like
what's shown in the illustration on the right.
If more pumps push water into a pipe the pressure (head)
will rise and actually hinder the efforts of each individual pump, thereby
lowering the actual flow theoretically expected.