Great idea Del. Thanks for thinking of integration. Hard to do with
just an op amp but it could be done using a gate. Easy to do with
a pressure sensor and a cheap ($1.00) single chip microcomputer
in software.  The output of the single chip would be a number
proportional to the area under the curve when the intake port
was actually open.
Paul Lamar

       As I suggested to Tracy, for noisy sensor signals coming into an
embedded system, it is often better to take the median, rather than the
average. 1) Sort the readings into an array as they come in. 2) Pick the
middle value.

       The median effectively ignores spikes and drop-outs and requires
no floating point math. You have to wait between readings anyway, and you
can bubble sort each new reading while you are waiting for the next
reading. Simple and robust.

       Bill Dube'

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