Ball Valves...

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Slugfoot
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Sun Jan 02, 2011 2:48 pm

...I've heard that they can be taken apart - with difficulty. Has anyone here actually managed this? If so, what technique did you use?
I would like to transfer the innards of a 2-way valve into the carcass of a 3-way one for use as a tap loading system. Does anyone know if this is even possible? :?
metalmeltr
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Sun Jan 02, 2011 2:56 pm

Doubt the parts would fit, but it should, be able to be taken apart.
If you have a vice and a long adjustable wrench with good jaws you should be able to take it apart with minimal damage. I tried to take a 3/4" valve apart with no sucsess i dont have a vice, or a good wrench, the one i tried is probably 30 years old-dad's.
Slugfoot
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Sun Jan 02, 2011 3:07 pm

Yup, I too suspect that the balls may be different sizes in each type. It looks like I may have to drill a hole in the top of a 2-way. I'm afraid of weakening it too much, though. :scratch:
metalmeltr
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Sun Jan 02, 2011 3:14 pm

What pressure you running at?
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velocity3x
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Sun Jan 02, 2011 3:16 pm

Ball Valves are extremely easy to disassemble / assemble. Once you separate the case halves, you'll see that there's no magic inside. If you don't have a vise.....two big wrenches and a little hammer shock on one wrench works too :) I doubt the ball will transplant into a different body.
metalmeltr
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Sun Jan 02, 2011 3:19 pm

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Slugfoot
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Sun Jan 02, 2011 3:32 pm

The device is not yet built so the answer is "nothing". - I'm still collecting bits and pieces as I go along. :D
Since I have a fridge compressor, I reckon I'll be running at about 300 - 400psi max.

Here is the butt assembly as it is now:-
Image - A similar arrangement to Hotwired's excellent Copperhead Prime.
Edit - A 3/4 qev piloted by a 1/4 qev. Pilot volume is negligible.



Also, my fridgie has a very small outlet tube on it - I just measured it at a tad under 5mm - and can't seem to find any compression fittings to fit it. - Any ideas here?





PS I just realised that I posted this in the wrong forum. - Sorry about that. Mods, please feel free to move it to a more appropriate area. :oops:
Slugfoot
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Sun Jan 02, 2011 3:38 pm

velocity3x wrote:Ball Valves are extremely easy to disassemble / assemble. Once you separate the case halves, you'll see that there's no magic inside. If you don't have a vise.....two big wrenches and a little hammer shock on one wrench works too :) I doubt the ball will transplant into a different body.
Yes, they seem very simple - a look at some cutaway images on google confirms this.

@ Metalmeltr - Yup, that's like what I have in mind.
metalmeltr
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Sun Jan 02, 2011 3:41 pm

I Would trust a larger-1/2-1" ball valve at those pressures with the hole the the side. What size valve did you plan to use?
Slugfoot
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Sun Jan 02, 2011 4:11 pm

metalmeltr wrote:I Would trust a larger-1/2-1" ball valve at those pressures with the hole the the side. What size valve did you plan to use?
This device will have a 22mm barrel so, um, yeah, I'll be using a 22mm valve/loader/thingy.
I'll have to have a good look at one and see if I can make a big enough hole without disrupting it's structural integrity too much. I suspect the hole might encroach on the threads on the housing - if you see what I mean. :?
Slugfoot
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Sun Jan 09, 2011 11:55 am

Bumped - To save starting another thread.


It is apparent that ball valves have superb flow characteristics and I see that a number of people have spring-loaded them (with success) in order to open them faster.
I was wondering if anyone has thought of firing them open with a small qev attached to the chamber operating a pneumatic cylinder/ram.
Does anyone else think this might work just as well as a spring? I am thinking it would also eliminate having to set up tricky mechanical trigger mechanisms.
....Just a thought. :idea:
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Technician1002
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Sun Jan 09, 2011 12:06 pm

With the addition of the cylinder and links, you add mass to the moving parts. The air cylinder is limited on the size of the air port into it. Newton has a few laws that limit what can be done with this method. With a spring, the force can be reasonable and the mass limited.
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saefroch
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Sun Jan 09, 2011 12:21 pm

Slugfoot wrote:I was wondering if anyone has thought of firing them open with a small qev attached to the chamber operating a pneumatic cylinder/ram.
That very well may work, but with the amount of effort required, I'd just build a piston valve.
Slugfoot
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Sun Jan 09, 2011 12:25 pm

...Acknowledged.
But, I'm also thinking now that one needn't use a commercial cylinder. One could cut the bottom off an old shock pump (using the piston and rod to attach to the ball valve lever) and fix it to a qev with a compression fitting - voila, a full bore pneumatic cylinder. An exhaust port at the end of the stroke would prevent too much force being applied.
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Vincenzo
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Sun Jan 09, 2011 12:43 pm

It's been done before, a few times.
more_eggs wrote:My teachers hated this one:
Teacher: "Matt, take your iPod out in class"
Me: "beg your pardon sir? I can't hear you, I'm listening to my iPod"
:P
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