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RE: [PSUBS-MAILIST] Ball Valves
Alec,
That seating of plastic against metal is relatively hard to seal at low pressures. You could make up a Teflon shuttle to replace the ball and that may fix your problem but without seeing the valve design I am only guessing. The only seat to use is one where a ball or shuttle seats against the metal but engages a soft seat such as an O'ring or such just before they hit the metal seat. Parker, Nupro have such small 1/4" valves with low cracking pressures. Sometimes an O ring will provide enough friction to hold the shuttle slightly off centre stopping from engaging fully and will weep as well until there is sufficient back pressure to allow full seating. Our 1/4" valve goes for $35 but is not suitable without modification. For best results you need to specify max pressure and the cracking pressure you want because if you have a rating for say 1000 psi then you need a more expensive option. Hope that helps. Chs Hugh
-----Original Message-----
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Smyth, Alec
Sent: 19 August 2009 06:40
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Ball Valves
Hi Hugh,
Aha, now I know your expertise I'm afraid I've got a question to suit!
I've long used a little SS check valve tee'd into the depth gauge
instrumentation line to bleed off cabin overpressure. It's of the sort
that has a little plastic sphere (actually a segment of a sphere) that's
spring loaded against a polished SS seat. Anyway, the valve works very
well and serves its intended function, but has an irritating tendency to
leak just a tiny trickle in spite of careful cleanings of plug and seat.
I don't mean there's a stream of water, but it drips constantly, perhaps
a drip per second or so. I forget what the rated pressure was, but the
pressures I'm using the valve at are way beneath the specified rating.
D'you have any recommendation for a check valve that might not have that
irritating leak? It must also have a low cracking pressure, just a
couple of psi.
Thanks,
Alec
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From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugh Fulton
Sent: Tuesday, August 18, 2009 2:36 AM
To: personal_submersibles@psubs.org
Subject: FW: [PSUBS-MAILIST] Ball Valves
Hi All, Guess this is our specialty. Excuse the plug here as we are
commercial. We have 1/4" through 6" valves. Stainless Steel or a
combination of Stainless and Aluminium in the 1" series and larger. If
you are wanting panel valves then that is a bit different. Ours are not
instrument valves like Swagelok and Parker but can be mounted to a panel
with our brackets.
These are designed for high pressure gas, so for air or water it is a
breeze. We also import some cheaper valves from other places. Take a
look
at the web site www.eclipsevalves.com We will do a special deal for
p-subbers but freight may be a problem. I will get our people to put up
a price list. We sell against Italian valves. However there are low
pressure valves on the market that are cheaper. Most of our valves
exceed 30,000 psi burst pressure with MAWP of 5000 psi plus. We are
also making some valves for subs such as Vent valves, Combination valves
2" with pneumatic and Manual shutoff in the same valve body.
Typically we can do a 5000 psi 1/2" valve for around the 80 dollar price
and a 2 inch #300 for US $250. Chs Hugh
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of glen brown
Sent: 18 August 2009 03:30
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Ball Valves
Hi James
I just received a quote for Worcester ball valves in south Africa i.e.
2'' @
$2000 .00 ect why does the cabin flood valve have to be so large ?and
why does the vbt valve have to be such a high quality ? I hope someone
can help Thanks Glen sa
----- Original Message -----
From: "James Frankland" <james@guernseysubmarine.com>
To: <personal_submersibles@psubs.org>
Sent: Monday, August 17, 2009 2:29 PM
Subject: [PSUBS-MAILIST] Ball Valves
Hi All.
Everything plumbing related that they have in my local store is SCHED 40
including the valves. They are only rated to 220 psi.
So, Im currently using specially ordered Worcester ball valves for
variable
flood, vent, cabin flood etc
They are the high pressure ones (cant remember the exact rating now) but
the
trouble is that they are REALLY expensive.
Any suggestions for some cheaper valves as i need to order a load of 1/2
inch ones and i nearly just passed away at the price of the worcester
ones.
What sort of valves have other people used?
Thanks
James
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