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Re: [PSUBS-MAILIST] MBT Venting Options



There's nothing secret about mushroom valves. It's a cylinder with a flat piston driving against a ledge for closure. I'll sketch something up and get it on the page one of these days. All it needs to open is a one inch stroke from a small pneumatic cylinder, the internal spring is enough to close it. The whole thing flush mounts through about a 3" hole in the top of your tank and fits nearly flush. All you need is an eighth inch line and a 3-way valve inside to operate it. One moving part, or two if you want to get technical, as the piston is nothing more than a flat disc of aluminum with a captured urethane gasket, center threaded and secured with lock nuts. No connections, or gears, or levers and the only spring is the cylinder's internal one.

I'll have all that stuff ready before the convention, so maybe I can get a little ten minute talk stuck in there on how to build these things. It's a home shop item. In fact, I guess a hacksaw and a drill would be enough, if you weren't interested in pretty. I wish we were sitting around a coffee table, because two minutes with a pencil and a napkin, and you guys would know exactly what I was talking about. I do have a new computer with a scanner and a new camera with a cable, so I'll snap some shots of the valves being built. We ought to be done here shortly, depending on when the cylinders get here. FedEx is pretty loaded down these days, but I'll post it soonest, whenever soonest happens to be. Soon, anyway.

Vance



-----Original Message-----
From: Brent Hartwig <brenthartwig@hotmail.com>
To: PSUBSorg <personal_submersibles@psubs.org>
Sent: Thu, 11 Dec 2008 3:48 am
Subject: [PSUBS-MAILIST] MBT Venting Options

Dan and Vance,
 
I like your idea much better then what I currently have Dan.  Some time I hope to see Vance's supper secret mushroom vent design. ;)'   You guys got me to thinking and I think I might have a even better option that has some elements of both your guys ideas.  A remote valve would need to be externally mounted above the highest point on the tanks in order to vent all the air. A large valve would stick out like a sore thumb or odd hood ornament.  Then I would have two rods going down at an angle with a small pair of U joints at each end, unless I use two pairs of bevel gears near the conning tower and a short vertical rod between them.
 
So what I was thinking was to have a piston type valve inside the top area of the MBT's with a 2 to 3 inch opening with a spring around the rod that protrudes vertically below20the piston head that has one or more soft O-rings mounted on it. Then to that I'll attach a horizontal arm to the bottom of the vertical rod, which is operated at the other end by a horizontal rod that goes through the pressure hull heads.  Then for the front MBT, the rod that is now inside the hull would have a small pair of bevel gears attached to it so you can go towards the port side of the hull. Once at the port side of the hull you have one more pair of bevel gears added so you can run a rod up to the pilot.  This way you can have a low profile valve that when you turn the lever to open it, you have to hold it there for a few moments until the tanks have vented, then when you let go they spring shut.  I saw a mini version of this piston valve on two inflatable pontoon fishing boats that I needed to let the air out of today.
 
Another option to operate this type of valve, is to not use the internal actuating assembly I just mentioned, and instead use a pair of Habonim pneumatic valves just inside the heads. One in front and one in the aft.  I've found them more commonly on ebay of late at very reasonable prices, from $50 to $150 each.  I prefer the Compact 4's but the Compact II's are nice as well.
 
 
http://shop.ebay.com/items/?_nkw=habonim&_sacat=0&_fromfsb=&_trksid=m270.l1313&_odkw=hamonim&_osacat=0



Regards,

Szybowski






To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] K-250 #118 In Action
Date: Wed, 10 Dec 2008 09:31:22 -0500
From: vbra676539@aol.com

Brent and Dan,

I converted mine to George's reach rod assembly. It works very well, of course, but was a pain in the A to do initially. To tell the truth, I'm not sure I would do it again. You still end up with tubing running from the fairwater tanks. Dan's suggestion of a valve on each tank is better. And use a BIG valve, an inch at the minimum. Waiting for the MBTs to vent is torturous through little tubing. My new ones, pneumatic mushrooms for lack of a better term, will be two inch clear opening. That's about the size on most of the old Hyco boats, and those boys dive quick when the time comes. Having spent a lot of time waiting as the sub wallows around trying to vent, I can tell you with certainty that faster is better.

Vance


-----Original Message-----
From: Dan H. <Jumachine@comcast.net>
To: personal_submersibles@psubs.org
Sent: Wed, 10 Dec 2008 7:46 am
Subject: Re: [PSUBS-MAILIST] K-250 #118 In Action

Brent,
 
If I were you I think I would consider filling all the little holes and using the big holes for a standard rotating through hull with linkage to valves mounted directly on top of the MBT's.  Or maybe plug all the holes and relocate new through hulls for the same purpose.  That way you can eliminate the need for plumbing to the valves and the through hull / valve combination.  The over all design may not look as clean but you can solve your valve and corrosion problems and they would vent much better also.   I know if I had mine to do it over again, I would have done it that way. 
 
Dan H
----- Original Message -----20
From: Brent Hartwig
To: PSUBSorg
Sent: Tuesday, December 09, 2008 2:46 PM
Subject: RE: [PSUBS-MAILIST] K-250 #118 In Action

Dan,

I don't see any thing like that.   It does have a standard snorkel, and you can see if you look carefully the downward turned float part of the snorkel.   I also thought it might be an extension of the snorkel but the picture shows the snorkel float as it was when I got it. 
 
Here are the pictures of the conning tower parts being removed.
 
I really don't like the multi-hole mounting design used for these valves. Dan isn't yours a single hole configuration that you turned some parts for it?  Also the exterior top area of the valv es holds some water, so that area got some heavy rust pitting I'll have to weld in.

Regards,

Szybowski





From: Jumachine@comcast.net
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] K-250 #118 In Action
Date: Tue, 9 Dec 2008 08:53:40 -0500

Not much of an idea Brent. 
 
It doesn't happen to have part of a 1950 Chevy pickup rear view mirror still stuck to it, does it? 
That's the only thing I can think of. 
 
Do you have a snorkel on it?  Most of the K-subs have one but it should be closer the conning tower, unless they added a piece of tubing.
 
Dan H. 
----- Original Message -----
Sent: Tuesday, December 09, 2008 3:06 AM
Subject: [PSUBS-MAILIST] K-250 #118 In Action

I had a couple of pictures that came with my subs documentation thats some of you have not seen. I don't know what the little rod coming out in front of the dome is for.
 
http://cid-5085d10eb6afe47c.skydrive.live.com/browse.aspx/K-250%20%7C3118%20in%20Action



Regards,

Szybowski



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