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Re: [PSUBS-MAILIST] MBT valve

Jay,
What I'm doing will fulfill your list to the letter.
1. One moving part (or two if you count the cylinder piston & rod) excluding operator valve inside sub
2. Zero hinge points
3. Soft urethane ring gasket mount, flat mating surface in tank required
4. Linear motion opened and closed (sealing area 1 and 1/2" ID X 2" OD ring/urethane to urethane, yielding about one and a third square inch of sealing surface under about a 4# constant tension load when closed)
5. Self contained and with enough sealing surface so that minor contamination shouldn't cause an issue
and two more:
6. The valve fails closed, and
7. The assembly is dead simple to inspect, dismantle, clean and repair, all done with a screwdriver and a couple of small wrenches.
Thanks for taking the lead with the illustration of a MBT valve.  I have taken the liberty to play with the design some, see the 3 images at http://flickr.com/photos/bottomgun in the MBT Vent Valve group.  I believe if you have a FLICKR account, you can view the images at a higher resolution.
 
Some thoughts:
1.       Want to minimiz e number of moving parts
2.       Want to minimize the number of hinge points
3.       Want to mount the complete valve assembly on the tank surface so that if there is give between the hull and the tank surface, closing tolerances and alignment will not be affected.
4.       Want seating surfaces to mate square on to insure complete closing of valve
5.       Seating surface material should be above the valve disk so sand or other matter doesn’t settle on it and allow air to leak



-----Original Message-----
From: Jay K. Jeffries <bottomgun@mindspring.com>
To: personal_submersibles@psubs.org
Sent: Sun, 11 Jan 2009 2:23 am
Subject: [PSUBS-MAILIST] MBT valve

Brent & Vance,
Thanks for taking the lead with the illustration of a MBT valve.  I have taken the liberty to play with the design some, see the 3 images at http://flickr.com/photos/bottomgun in the MBT Vent Valve group.  I believe if you have a FLICKR account, you can view the images at a higher resolution.
 
Some thoughts:
1.       Want to minimize number of moving parts
2.       Want to minimize the number of hinge points
3.       Want to mount the complete valve assembly on the tank surface so that if there is give between the hull and the tank surface, closing tolerances and alignment will not be affected.
4.       Want seating surfaces to mate square on to insure complete closing of valve
5.       Seating surface material should be above the valve disk so sand or other matter doesn’t settle on it and allow air to leak
6.       Seating material should be a soft elastic material
7.       Operating cylinder should fail in the valve closed position (some cylinders have springs installed and air pressure operates against the spring below the piston, not sure if Bimba has this capability)
 
Bimba cylinders, 3-D models in v arious formats are available on their web site:
http://www.bimba.com/
 
R/Jay
 
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
 
As scarce as the truth is, the supply has always been in excess of the demand.
    -Josh Billings