Hi All,  With all of the work I'm doing with valve facing materials,
I've also been doing a lot of reading.  One thing that puzzles me
somewhat are the various terms I've found.  There's 'the vacuum side'
and 'the atmosphere side'.  There's the 'upper' and the 'lower'.  And,
there's the 'top' and the 'bottom'.

Personally, I've always referred to the facings as 'intake' and 'exhaust'.
My thinking is simple; 'intake' lets the good stuff 'in' and 'exhaust'
lets the bad stuff 'out'.  The good stuff is the vacuum.  The bad stuff
is the atmosphere.

Now I realize the you don't actually 'let vacuum in' or 'let atmosphere
out'.  In every case, the atmosphere is always trying to equalize the
negative air pressure.  Not the other way around.

I'm reminded of something someone said: If a window gets shot out of
an airplane at 35,000 ft, things don't get sucked out of the airplane.
They get blown out by the comparatively positive pressure inside the
plane.  And as soon as the pressures equalize -- well, you die in less
than 30 seconds unless you're really, really lucky... but that's a
whole other story.  But I digress...

What I'm really looking for is an explanation for the terms 'upper' and
'lower' or 'top' and 'bottom'.  The reason I'm asking is because quite
a large number of player systems have horizontally inclined valves.
So, there is no 'upper', 'lower', 'top', or 'bottom'.  And, if 'upper'
and 'top' refer to the atmosphere side and 'lower' and 'bottom' refer
to the vacuum side, where is that explained so a novice can find it?

By the way, if this seems like a dumb question, I would remind you that
Carl Sagan, in his work 'The Demon-Haunted World: Science as a Candle
in the Dark,' said: "There are naive questions, tedious questions,
ill-phrased questions, questions put after inadequate self-criticism.
But every question is a cry to understand the world.  There is no such
thing as a dumb question."

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA