Simple Ball-Float Shut-off Valve Design

[vonsteimel]

Greetings,
I've been looking for a simplistic Ball-Float Shut-off Valve for weeks and cannot find them anywhere. They do make the simple Ball-Float Shut-off Valves but they are much too large for my application. All the Ball-Float Shut-off Valves I could find were designed as a simple shut-off valve to prevent overfilling of large storage tanks. This meant they were all big, as the smallest I could find was still well over an inch in diameter. (A good image of such a valve can be seen attached as "valve_example.jpg")

http://files.engineering.com/getfil...4d01-9082-27aa601ca535&file=valve_example.jpg

Ideally, I'd prefer a 1/4" diameter float but I thought the buoyant forces might be too small to allow a proper shut-off therefore we're going to try a 1/2" float ball and reduce the diameter after the float portion of the valve. I have found a reliable source for finely polished, 1/2"Dia hollow aluminum "float" balls. I'm looking to replicate what is seen in "valve_example.jpg" as closely as possible.

The reason I have posted this here is I'm looking for design practices & guidelines for simple ball-float shut-off valves. For instance, what is the best "angle" for the ball seat within the valve body? (see attached image "Design.jpg") -- Also, the fact that no manufacturers of such a valve can be found leads me to believe there may be other considerations hindering the design/production.

http://files.engineering.com/getfil...6-3ec7-4be7-864e-8d691c741278&file=Design.jpg

Some other considerations are:
- float cannot be placed on an arm to gain leverage (as found in toilets) due to very tight space requirements.
- must be very simple & cheap (ball float only; no piston/plunger)
- may be used-in/exposed-to gasoline, oil and/or alcohol therefore must be highly chemical resistant.
- pressure will not exceed 3 psi;- will only spend approx 5% - 10% of its life submerged; must be corrosion resistant
- gasses must be allowed to enter & exit freely when not in the shut-off position (gas movement will be very slow & not pressurized)
- forces considered are only related to liquid trying to exit the valve; never will liquid be forced into the valve (as there might be in an over-fill protection valve) therefore it is not a design consideration.

 

[vonsteimel]

The 2 links in the post above are shortcuts to the photos I attached to the post.
Thanks,

VS

 

[hydtools]

You might contact Vernay:

http://www.vernay.com/e-commerce/ProductList.aspx?pg=V-ball

Ted

 

[vonsteimel]

Does anyone know where I can find formulas, guidelines & information regarding the design of simple ball-float shut-off valves? Or if anyone has such information in their heads, would they please share it?
Thanks,

VS

 

[IRstuff]

You might check old carburetors and associated textbooks. There used to be small float valves inside the carburetor bodies that ensured the small reservoir in the carburetor was at the fill line, ala

http://www.vw-resource.com/float_needle.html

Note that the force generated is simply that from Archimedes principle, i.e., the weight of the fluid displaced by the volume of the float. Therefore, even a a 1/4" float may be too small. Carburetor floats were on the order of 3/4" x 1/2", but this was for gasolne.

TTFN
faq731-376

 

[stanier]

Have you looked into the cistern of your toilet? There is quite a sophisticeated mechanism for a dual flush unit.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[vonsteimel]

Thanks for the input everyone. I'm actually looking for the opposite of "sophisticeated" but thanks for the advice. Ill be checking back here every so often so if anyone stumbles on here with any additional info, please share it. Thanks,

VS

 

[gerhardl]

The construction you are looking for exists (as a principle) for integral pneumatic ball check-valves for pneumatic air, produced by a multitude of companies. I would suggest SMC and Norgren as two of the companies with a large number of material combinations and constructions.

I am in doubt if you could directly find a working solution for your purpose, but you could perhaps come quite close, or buy samples or get technical leaflets to study proportions.

I believe you will find constructions and materials of housing and sealing within your target area, problem to study or reconstruct: floating properties of ball.

The best of larger size (say one inch or more) floating balls (for air outlet by overpressure, air inlet by underpressure and blocking water out by high water level) are, as known, constructed with hollow resin cells, supported by 'beecube cellwalls' inside to strengthen against misforming.