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<div><font size="3">Alec,</font></div>
<div><font size="3">As for the slow-motion dive, it seems it would be a good idea to have a threaded plug or something similar to seal the vents when you have to leave the sub in the water unattended. Your thoughts?</font></div>
<div><font face="Arial, Helvetica, sans-serif" size="3">Jim</font></div>
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<div style="color: black; font-family: arial,helvetica; font-size: 10pt;"><font color="black" face="arial" size="2">-----Original Message-----<br>
From: Land N Sea <landnsea1@hawaiiantel.net><br>
To: Personal Submersibles General Discussion <personal_submersibles@psubs.org><br>
Sent: Sat, Nov 23, 2013 3:31 pm<br>
Subject: Re: [PSUBS-MAILIST] MBT valve<br>
<br>
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<div>I would also be concerned about not being able to get a GOOD seal when
closed. Also I imagine that you would want to keep running the motor for a bit
after the valve has seated to make sure there is a bit of pressure against the 0
ring and I am wondering if that would cause the breaker to pop?</div>
<div>I like the idea of being able to dump the MBT’s fast though as I am in the
same boat, pun intended, and wish Kittredge would have upgraded the size of the
pipe vents on the plans.</div>
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<div>Rick</div>
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<div style="font-color: black;"><b>From:</b> <a title="alecsmyth@gmail.com" href="mailto:alecsmyth@gmail.com">Alec Smyth</a> </div>
<div><b>Sent:</b> Saturday, November 23, 2013 7:48 AM</div>
<div><b>To:</b> <a title="personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">Personal Submersibles General
Discussion</a> </div>
<div><b>Subject:</b> Re: [PSUBS-MAILIST] MBT valve</div>
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<div dir="ltr">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.
<div> </div>
<div>:)</div>
<div><br>
Alec </div>
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<div class="gmail_quote">On Sat, Nov 23, 2013 at 12:35 PM, hank pronk <span dir="ltr"><<a href="mailto:hanker_20032000@yahoo.ca">hanker_20032000@yahoo.ca</a>></span> wrote:<br>
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<div><span>Jon,</span></div>
<div><span>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. </span></div>
<span class="HOEnZb"><font color="#888888">
<div><span>Hank</span></div>
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<div dir="ltr"><font face="Arial">On Saturday, November 23, 2013 10:10:28 AM, Alec
Smyth <<a href="mailto:alecsmyth@gmail.com">alecsmyth@gmail.com</a>> wrote:<br>
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<div dir="ltr">Hi Jon,
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<div>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.</div>
<div> </div>
<div>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. </div>
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<div> </div>
<div>Best,</div>
<div><br clear="none">Alec</div>
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<div>On Sat, Nov 23, 2013 at 11:51 AM, Jon Wallace <span dir="ltr"><<a href="mailto:jonw@psubs.org" rel="nofollow" shape="rect">jonw@psubs.org</a>></span> wrote:<br clear="none">
<blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;"><br clear="none">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.<br clear="none"><br clear="none">Illustration.<br clear="none">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.<br clear="none"><br clear="none">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.<br clear="none"><br clear="none">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.<br clear="none"><br clear="none">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.<br clear="none"><br clear="none">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?<span><font color="#888888"><br clear="none"><br clear="none">Jon<br clear="none"><br clear="none"><br clear="none"><br clear="none"></font></span><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a href="mailto:Personal_Submersibles@psubs.org" rel="nofollow" shape="rect">Personal_Submersibles@psubs.org</a><br clear="none"><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank" rel="nofollow" shape="rect">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"><br clear="none"></blockquote></div>
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