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Date: Tue, 29 Jun 1999 21:13:37 -0700
To: lancair.list@olsusa.com
From: "Mike S. Reinath" <mreinath@mail.arc.nasa.gov>
Subject: Re: Leaking gear dump valves
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>>
I was getting ready to order the NUPRO plug valve a few days ago when I
noticed the following in my Swagelok catalog:

P4T (brass and 316ss) is rated for 3000 psig at 70 deg F
P6T (brass) is rated for 2000 psig (316ss) is rated for 3000 psig  at 70 deg F

with the following note:
"If reverse flow occurs, differential pressure is limited to 150 psi max.
In such cases, the valve should be actuated quickly to prevent O-ring
damage."

There is a arrow stamped on the side of these valves. They are rated for
the high pressure in the direction of the arrow but not in the reverse
direction, if I am understanding the note correctly.  I don't think this
type of valve is a good choice for our gear dump valve.

They have a series of Ball Valves which are similar in size and do not
appear to be directional. Check the 40 Series Ball Valves.

Mike Reinath
N3602M


[Just an observation, Mike, but if you think a bit about our application
you will notice that it _is_ quite directional... we will never 'dump'
the low pressure side, only the high pressure.  There should never be
reverse flow in the system at all.  When the valve is closed there is no 
flow whatsoever, so I think you're being concerned about a non-issue.
As I said earlier, though, this is just an observation... I could be
wrong, as I think I was wrong once before <G>.        <Marv>   ]


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