Hi Folks,  David Greene asked [130101 MMDigest] about obtaining
a gauge to use while regulating a reproducing piano.  While it is easy
to make and use a water gauge using plastic tubing from a 'big box'
[hardware] store, it can be messy and it's easy to make a mistake in
reading it (although it is quite accurate and precise).

It's a lot better to buy yourself a nice Dwyer-Magnehelic pressure
gauge.  While they are a little pricey at retail, you can buy them
rather inexpensively on eBay.  I have about a dozen for different
ranges.  Check the Dwyer web site to learn how to determine the range
from the model number and then search on e-Bay for Magnehelic.  There
are usually several dozen to chose from.  They range from $5 to $20 if
you don't insist on one new in the box.  (One went for only $0.99 but
shipping was $11.)

And you don't need a positive-to-negative (center zero) gauge, as they
can all be used either way.  They also read either absolute or
differential pressure.

By the way, check out the internal drawings on the Dwyer web site.
It's really interesting to see how these gauges work and why they are
called Magnehelic.

Regards
Craig Smith
Upstate New York