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I took the information from the Parker book and had the groove machined as
per. This was after a long phone conversation with the design guys at
Parker.
The groove was straight down with no taper. The bottom corners are slightly
rounded. The groove is slightly wider than the O ring.
I'm not happy with the result. The O ring has a tendency to fall out. I
would suggest making the inside leg of the groove taper at 5 degrees. This is
suggested in the Parker book. Actually, the book shows a taper so it's wider at
the top of the groove ( definitely no good ) but there's a note about making the
taper wider at the bottom ( ya, that's the right way )
The groove is wider than the O ring so the rubber has a place to go when
it's compressed under pressure.
My O ring is 22 inch I.D. and so is the groove. I should have made the
groove a tiny bit bigger so the O ring has to stretch slightly, there by holding
it in the groove.
The cost for machining flat the flange and cutting the groove was
$300.
If I wanted a taper, it would have been a little more, but now I wish I
would have done that.
I put some rubber cement ( glue ) in the groove and it works.
The cost of the O ring is also a problem. If you buy 50 pieces, they are
$17 each. I only needed one, and bought an extra one just in case. The cost was
over $100. Kinda got screwed there. You can get an O ring made from roll stock
where they glue the ends together and it's a lot cheaper, but I didn't want a
split in the ring.
Anyway, what I would suggest is......put a taper on the groove, and make
the O ring a snug fit. Shore 70 is a good hardness, and don't worry about
extrusion of the O ring. The pressure is trying to force the rubber between the
flanges, and if you've got two flat surfaces, it won't leak.
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