SpudFiles

This is the way I build a high pressure self-closing piston valve (barrel sealer).

min. actuation pressure: 30 psi (varies due to the used spring and piston)

The parts:
1/2" quick connect (only to connect a blowgun, not to pressurize)
3/4" female to 1/2" male
1" female to 3/4" male
1" nipple (find one with a smooth surface inside)
1" tee
3/4" hose barb
1" to 3/4" reducer
1 bolt 2 fitting nuts
3 sealing gaskets (3/4")
1 washer -> size of the sealing gasket
2 washers -> I.D. of the 1" nipple



Step 1:
Screw the 3/4" hose barb into the 1" to 3/4" reducer and then the reducer into the 1" tee.
Nice about these hose barbs is that they have short threads, so there is enough space to add multiple barrels.



For this valve I chose a large tee compared to the "barrel" to have a good air flow and a smaller pilot chamber.



Step 2: build a piston (optional way)
This is basically a bolt piston but with two tricks I want to show you.

If you have ever build a bolt piston you might have realized that it is not that easy to get the washers into one line. Simply take two nuts and grind one side of them to form a cone. This way your washers are always centered (you can see it on the right nut on the picture).

To make the piston seal, take two sealing gaskets that are little smaller than your housing (in this case 1" nipple -> 3/4" gasket). Place them between two washers and nuts. Now screw the nuts so that the gaskets squeeze out. This way you get a perfect sealing piston.



Step 3: Assembling of the pilot section
Quick connector -> 1/2"male to 3/4"female -> 3/4"male to 1" female

Optional: Quick connector -> 1/2"male to 1" female (if you find one, even better)


Step 4: Finding the right spring (this step needs some tweaking)
You have to find a spring that is not to strong or to weak.

to strong: The piston only opens at very high pressure with bad flow or it doesn't open at all.
to weak: The piston doesn't seal and the air leaks out of the barrel.

If you think that you have the perfect spring but the air still leaks out of the barrel then your piston might seal to well in it's housing. A little equalization should be installed.



Picture of the pilot chamber. It's already small but still improvable. The valve can be actuated with a blowgun @ 30 psi.

Great how-to for those beginning to work with metal rather than PVC, and just informative in general. All your posts been great so far keep it up!

Nice clean job. Its amazing how similar this is to the piston that I put together for my hybrid project, except that mine is a chamber sealer that is blown open by the combustion. Its interesting to see how two independent ideas can come out so much alike.

Great how-to for those beginning to work with metal rather than PVC, and just informative in general. All your posts been great so far keep it up!

I second that... lol Jmeyer that's exactly what I had in mind...

@MRR I like that you used a hosebarb that was very clever and simple at the same time


feel free to add more good stuff

The valve should seal without a spring...

Thanks fore the kind comments, I really appreciate that.

@mark
The concept of that valve is to power a semi auto. The quick connect is only to attach the blowgun. I fill the chamber from another place, it's simply faster than pushing the pressure through a small equalization hole.

Quick question MRR, What's total cost for the valve? I'm looking to build a copper pneumatic to go with the fridge compressor I recently got. I love my 2" golf ball cannon but the neighbors don't.

I got the parts + a 1 meter copper barrel from a friend for 20€~25$ (he is a plumber and doesn't pay VAT).

I suggest using malleable iron fittings where possible to cut costs

I'm a bit confused on how you got the hose barb inside the tee.

Can you screw the hose barb into the reducer from side with the 1" threads on the outside? I thought the threads would only match up if you screwed it in from the 3/4" side?

Could someone clarify this for me?

Other than that its a great write-up.

great work
I made something similar before but without a spring

daberno123: you can screw the hose barb in the other side of the 3/4 reducer
then screw that with the hose barb pointing in inside the T

there is enough space left on the other side for a barrel

jmeyer1022 wrote:Great how-to for those beginning to work with metal rather than PVC, and just informative in general. All your posts been great so far keep it up!

I third that! (In a corny tone)
This how-to is just as good as all you're others and I think it will benefit all spudders alike. (In a noble tone)

sniper hero wrote: you can screw the hose barb in the other side of the 3/4 reducer
then screw that with the hose barb pointing in inside the T

Do you have to grind away any lip or anything on the reducer?

Looks nice and pricey cause of brass. The look reminds me of a "French QEV" or as they like to call it.

Nice job

nice man this is so pretty

so how much pressure can handle ! the max ?