<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span>Jon,</span></div><div><span>I think a first stage regulator is 140psi above ambient, if the regulator is in the water it will always be 140 over ambient.</span></div><div><span>Hank</span></div><div class="yahoo_quoted" style="display: block;"> <br> <br> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div dir="ltr"> <font face="Arial" size="2"> On Saturday, November 23, 2013 5:31:23 PM, Jon Wallace <jonw@psubs.org> wrote:<br> </font> </div> <div class="y_msg_container"><div id="yiv4474079086"><div>
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A 600psi valve should be fine on the 350 as long as you keep any
static pressure for the fill side a safety margin below, perhaps
no higher than 350psi. A first stage on your hp tank indicates a
flowing pressure of 150psi or there abouts (the first stage
standard). The bigger issue you have to deal with using a typical
first stage is that the air pressure is close to equalizing the
pressure at 337 feet. If you push the vessel to it's limit you
could end up in a situation whereby you can't blow ballast because
the outside pressure equals or is greater to that being put out by
the first stage. <br clear="none">
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On 11/23/2013 2:46 PM, Pete Niedermayr wrote:<br clear="none">
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<pre>I found these 3 way valves that have an off position. I want to go with the Vent/Off/Fill idea I mentions a few months back. I'll have a 1st stage reg on my HP tanks. the valves are rated 600 psi WOG is that high enough ? The K350 spec'ed one are 1000 psi. Any thoughts ?
On Sat, 11/23/13, Alec Smyth <a class="yiv4474079086moz-txt-link-rfc2396E" href="mailto:alecsmyth@gmail.com" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:alecsmyth@gmail.com">mailto:alecsmyth@gmail.com</a> wrote:
Subject: Re: [PSUBS-MAILIST] MBT valve
To: "Personal Submersibles General Discussion" <a class="yiv4474079086moz-txt-link-rfc2396E" href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">mailto:personal_submersibles@psubs.org</a>
Date: Saturday, November 23, 2013, 9:48 AM
One more thing... I'm not
sure how easy it would be to get a really accurate seal if
you make the body from PVC. I always find plastics
challenging when it comes to machining tolerances. For
surfacing the sub a tiny valve leak is no problem, in fact
you wouldn't even notice it. But a tiny leak is a
nuisance, because the sub will have a tendency to dive
herself in slow motion when you leave her at the dock for a
few hours, when she's under tow, etc.
:)
Alec
On Sat, Nov 23, 2013 at
12:35 PM, hank pronk <a class="yiv4474079086moz-txt-link-rfc2396E" href="mailto:hanker_20032000@yahoo.ca" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:hanker_20032000@yahoo.ca">mailto:hanker_20032000@yahoo.ca</a>
wrote:
Jon,I have to agree with
Alec. I would not use an electric motor. If it has to be
electric, I would also go with solenoid valves. I have
personally used solenoid valves on my salvage rov and in
about a million dives we never had a single issue except for
freezing when the rov surfaced in the winter. Electric
solenoids are also safe in your case because you have
multiple mbt's and you should wire them separately.
Hank
On Saturday, November 23, 2013 10:10:28 AM,
Alec Smyth <a class="yiv4474079086moz-txt-link-rfc2396E" href="mailto:alecsmyth@gmail.com" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:alecsmyth@gmail.com">mailto:alecsmyth@gmail.com</a>
wrote:
Hi
Jon,
Personally if I used a
remotely operated valve I'd be much more comfortable
with actuating it pneumatically than electrically, for
reliability. This is after all the MBT valve, arguably the
one thing on the sub that has to be the most reliable of
all. If for some reason it just had to be electric, then
I'd suggest using an electromagnet instead of a motor.
The magnet would act against a spring so that the valve was
of the normally closed type, and you could still surface if
the electrons got wet.
What I don't like about
the K valves is the way George mounted them. But I'm a
fan of the approach if you add a proper through-hull for the
shaft, sealed with O rings instead of RTV like the original.
If using a large bore valve, I'd add one more detail,
which is to put round handles on them instead of straight
ones. That's so that someone getting in or out of the
sub won't dive it by snagging their clothes on the
handles.
Best,
Alec
On Sat, Nov 23, 2013 at 11:51 AM, Jon
Wallace <a class="yiv4474079086moz-txt-link-rfc2396E" href="mailto:jonw@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:jonw@psubs.org">mailto:jonw@psubs.org</a> wrote:
Looking for feedback on this MBT poppet design (see
attachment). It is very similar to the poppet Vance showed
us in Islamorada but driven by an independent electric motor
rather than pneumatic. My goal is to move to an electric
or pneumatic replacement for the Kittredge MBT ball valve
thru-hull design for various reasons. First, I don't
like the valve handles sticking in through the conning
tower; second, I am adding saddle tanks for additional
buoyancy which would mean adding at least one more valve;
third, my saddle tanks are going to be big and I want a
large diameter valve to provide quick venting.
Illustration.
The valve is made out of PVC plumbing material available at
any good hardware store. The square main body is a 4-inch
PVC coupling. A series of 1-inch holes drilled into the
end allow venting when the "plunger" is retracted
back to the motor side. The "stop" on the closed
side would have a gasket to provide an air-tight seal.
The motor is a cheap electric screwdriver motor such as
Black & Decker AS6NG. It has plenty of torque,
reversible, and is low power (2-3vdc). When the body is
removed the "guts" fit nicely into 1.5 inch PVC
piping. The rotating socket tip will be waterproofed using
a home-made "Blue-Globe" type attachment. Oil
compensation will ensure the housing doesn't fracture at
depth although theoretically 1.5 inch PVC is pressure safe
to well beyond the depths I will be diving.
The piston will be 1/4 inch thick (6mm) and can be aluminum
or even 1/4 to 3/8 acrylic. It is attached to the coupling
nut by a 1/4-20 threaded rod. The coupling nut is
permanently attached to the rotating socket tip of the
screwdriver by either epoxy or light welding. As the motor
and coupling nut turns, the threaded rod is drawn into the
coupling nut pulling the piston toward the motor and
allowing the MBT to vent. Reverse the motor and the piston
is forced back down to the closed position and seals the
MBT.
I have already prototyped the motor and it's PVC housing
and they fit together very well. Cost of battery operated
screwdriver is about $10-20 (US). PVC of course, is cheap.
I am looking at 4-inch material but this design could be
easily scaled.
I see lots of pros; looking for cons and potential issues
with the design before I fully prototype it. Any of you
CAD'rs interested in creating a nice 3-D drawing for
me?
Jon
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