Push button valve question

[btrettel]

I've been eying McMaster-Carr part # 62475K11 for a while. I intend to use it to both pilot and refill my air chamber in a new gun I'm planning. However, this valve doesn't have the flexibility of a valve with 3 outputs because one of the outputs here is only for exhaust. If the inlet is attached to, for example, a QEV, when the button is pressed, would the pilot air go out the exhaust as opposed to the other port (which would have to be sealed off)? This is a little confusing so I can reexplain if anyone is confused.

[POLAND_SPUD]

I suppose you want to use a 3 way version?? not a 5way valve (which is in fact a 4way valve) ?

a 3 way version should work ok IMO...
just look at the diagram.. A QEV goes where the air cylinder is and that is it...

joining a QEV to the air exhaust (EA in the pic) doesn't make any sense at all... the point in using a 3 way valve is that you can switch between filling and piloting.... this port is not the one that's meant to be used to acomplish this (meaning - it would close off a QEV in one position instead of switching between filling/piloting)


just an interesting detail.... a 5 way valve gives you more freedom in choosing different ports.. provided it's a spring return valve... have a look here.. in mine I can connect air source only to one port... otherwise it won't work

have a look here

http://www.spudfiles.com/forums/solenoi ... 16722.html




oh finally one more thing...If I can suggest something choose a 1/4" version with threaded ports... 1/8" ones might not have sufficient flow to pilot bigger valves... push in fittings may also lower flow...
in the long run it might be cheaper to pay a little bit more than having to buy an additional qev for piloting the main valve of you future project/s

[btrettel]

My explanation probably confused you. All I want to do is semi-auto with a QEV.

Is P the inlet? That's my main question I suppose. If P is the inlet I'm going to have to use metal 10-32 fittings, which are a little expensive and small enough to restrict flow.

I sadly don't have the budget for any other valves, but it might be worth investigating a source other than McMaster-Carr.

Edit: If this doesn't work like I want it to, I think I'll go with 46095K51. It costs twice as much, but after the little fittings I'd need to get the push button valve to work it'd be comparable, and it'd have significantly more flow. If I modify it so I can use a trigger it should work well. If not I can always return it, though McMaster-Carr's not been giving me back as much as I hope for.

[POLAND_SPUD]

so just look at the diagram for a 3 way version on mcmaster.. A QEV goes where the air cylinder is and your source of air is hooked up to P... that's it

if you want to build a semi with an air cylinder a 3 way valve is all you need... infact a 3 way valve is better than a 5 way becasue the former doesn't waste air from the air cylinder



what are 10-32 threads?? are they just 5mm threads?

[btrettel]

Yes, I would put the QEV at A, but the 10-32 threads would be annoying. 10-32 fittings are small. Their threads are exactly the same as 10-32 screw threads, they are relatively uncommon, and they can be expensive if you only want to use one or two because packs of them are for 10 or 20 and they cost about $10.

I think I'll go with the ball valve I mentioned in an edit in my last post if A is where I'd have to hook it up and A is the 10-32 threaded side.

[POLAND_SPUD]

if you are desperate and if MC master doesn't have any other manually activated directional control valves you can either:

a)check other sites... IIRC PVC arsenal bought a nice valve from pneumadyne and used it in his nerf semi auto

b)buy the valve you mentioned in your first post in 1/8" version and join it with a 1/4" QEV for faster piloting...
and yeah I know that I said just the opposite in one of my posts...


so 10-32 threads are just 5mm metric threads... you never stop learning... liffe would be so easy if there was only one type of threads

[PVC Arsenal 17]

What you want is a 3-way, normally open valve.

With that type of valve, there is an inlet, an outlet, and an exhaust port.
Air normally flows through the inlet into the outlet. Upon pushing the button down, this flow is stopped. Any remaining pressure on the output side of the system is vented.

Try Pneumadyne part# A11-31-44

Pneumadyne also sells handy actuating levers that make for nice triggers.

You can try McMaster part# 4622K51. That's a sleeve valve. More commonly known as a slide check valve. Here's a diagram of how they work:


(A 3 way, normally open valve works the same way)

The valve you mentioned will not work exactly as you want it to. It is a normally closed valve. If you want to achieve semi-auto with that valve, your gun will fire only when you release the trigger.

so 10-32 threads are just 5mm metric threads... you never stop learning... liffe would be so easy if there was only one type of threads

Damn... I never knew that either. That could have saved me a lot of time though...

[btrettel]

Thanks PVC Arsenal, that answered every question I had! I had thought the valves on McMaster-Carr weren't quite right so I was hesitant to buy them. Pneumadyne looks like a great source so I'm looking right now... A11-32-44 looks spot on but is a little expensive.

[PVC Arsenal 17]

Thanks PVC Arsenal, that answered every question I had! I had thought the valves on McMaster-Carr weren't quite right so I was hesitant to buy them. Pneumadyne looks like a great source so I'm looking right now... A11-32-44 looks spot on but is a little expensive.

If they're inadequate I think I'll try the 3-way ball valve because of the high flow, but I doubt they are.

Actually they are inadequate for larger pilot volumes. You should really consider using a smaller QEV in conjuction with the 3-way to pilot your main QEV if it's a big one.

But a push button valve is great when you need a trigger. Pneumadyne doesn't actually sell that valve on their online catalog but if you call them up they should be able to make one for you. They have excellent customer service.

If you don't need to have a fancy trigger, those sleeve valves are the way to go. McMaster offers a bunch of different sizes. I own their 1/8" one it works great. You can't go wrong with one of those if your pilot volume is large.

[POLAND_SPUD]

The valve you mentioned will not work exactly as you want it to. It is a normally closed valve. If you want to achieve semi-auto with that valve, your gun will fire only when you release the trigger.

@ PVC arsenal at first I thought I made a big mistake by not stressing the fact that it has to be a normally open valve... but then I've checked again and the valve mentioned by btrettel is a normally open valve

NFPA diagrahms (if that's what made you think it was a NC valve) always show what happends after pressing the button/actuating the valve on the right side of the diagrahm, left side is for 'normal' position...

mcMaster has even written 'position 1' & 'position 2' next to each half of the diagrahm

[btrettel]

I'm using a 3/4 inch QEV. Is that too big? If so then I'll just use the 3-way ball valve I mentioned earlier. I don't have the budget for a second QEV and it would be too large for what I'm interested in doing.

This gun uses a push button directional control valve for a trigger and a 3/4 inch QEV, so I think the DCV should be okay, though I don't really know.

@POLAND_SPUD: McMaster-Carr says they are normally closed as far as I can tell:

Spring-Return Valves— A spring returns the valve to its original position once you let go of the operator. Single-pressure-output (3 way) valves are normally closed.

[PVC Arsenal 17]

See that's what I thought when I bought # 62475K22. I went by the diagrams. Unfortunately I was wrong and now I have a valve with no purpose.

If you read McMaster's description of this category it says:

Spring-Return Valves— A spring returns the valve to its original position once you let go of the operator. Single-pressure-output (3 way) valves are normally closed.

EDIT: Btrettel beat me to it. But yeah, they're NC.

[btrettel]

McMaster-Carr accepts returns, even years after you bought it. I'd highly suggest taking advantage of that... if you're a repeat customer who sometimes buys things and finds out they're not right, you can rack up hundreds of dollars worth of returns. I have received at least $400 (probably about $500) from them for my returns now that I think about it.

Do you think a 3/4 inch QEV is adequate for a push-button valve?

[POLAND_SPUD]

http://www.mcmaster.com/catalog/114/gfx/small/3w2ps.gif <- position 1 is normal, 2 is when you actuate the valve...
to see it properly I suggest you to just open the page... gif doesn't show which one is which




PVC arsenal is right that it would be better to combine a push button valve and QEV and use them both for piloting...

in fact quite a lot of large ( bigger than 1/4") manually controled valves are in reality just air operated 3/2 and 5/2 valves that are piloted by smaller manual valves...
both valves are incorporated into one or they manufacture them seperatelly so that it is possible remove the 'piloting' manual valve and replace it with a solenoid or the other way round

[PVC Arsenal 17]

@Btrettel: The gun you posted shows a push button valve with a threaded exhaust port (I think...)

The 3-way I have used exhaust air around the button. There isn't much flow going on there. I would guess that if the output is a full port then it can handle it.

Stick with the ball valve or maybe consider a sleeve valve.

And yeah, I probably should get around to returning all that stuff...


@POLAND_SPUD: I maintain what I said- those valves are normally closed, Don't go by those diagrams. McMaster directly stated it and the fact that I own one under that category should be proof enough.
BTW: McMaster's 3-ways are manufactured by Pneumadyne. (Who doesn't sell N.O. valves unless you special order them)