At 01:43 PM 2/6/2001, Bill Davidson wrote:
>Sealed Box? I don't follow... please explain...

A pressure gauge measures the difference in pressure between two points,
specifically the inside and the outside of the Bourdon tube.  Usually the
outside is exposed to atmospheric pressure, and the reading is called
"psig" for gauge.  On some guages the mechanism is kept in a vacuum, and
the reading is "psia" for absolute.  For this application you're trying to
find out the pressure difference across the injectors, so you would like
the outside of the bourdon tube to be exposed to manifold pressure.  One
way to do this would be to bury the gauge inside the manifold; another
would be to seal it in a box with a window and run a line from the box to
the manifold.  Yet another would be to use a gauge designed for
differential-pressure measurements, but I think they tend to be $$.

d

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"