1/2" QEV or 3/4" sprinkler valve

[LCTChamp]

I am planning on building a small bore pneumatic gun. I plan on using a .40 caliber blowgun as a barrel so I can use darts. I wont be using pressure over 100psi because my only source of pressure is a bike pump at this moment. At about the same price which would be a better valve to use the 1/2" QEV or 3/4" sprinkler valve? How would a attach the blowgun barrel to the gun? Epoxy?

[FishBoy]

QEV i would guess, at least for that barrel.

[LCTChamp]

Is there a specific reason for that choice?

[Velocity]

QEV's have several advantages over sprinkler valves:
1) More durable construction
2) Greatly improved opening times
3) Better flow

A think a 1/2" QEV will have greater flow than a 3/4 sprinkler valve...it will be close anyways.

[LCTChamp]

What kind of epoxy would I use to attach the barrel?

[jook13]

Read the epoxy packages. It will usually state what it is designed to bond to.

[jon_89]

I would just go for the sprinkler if you are using blowgun darts. I use a blowgun barrel with a sprinkler and I can shoot a dart 30 feet and go through a .5 inch plank.
Edit: That was using only 30 psi, 1 inch by 5 inch chamber, and a 24 inch barrel.

[psycix]

Besides the way faster opening times and the metal construction allowing higher pressures, the QEV will probably have about the same flow of the sprinkler.
QEV is way better.

[jon_89]

I agree with everybody on the QEV if you intend to use different barrels such as a marble barrel but as stated above for blowgun darts a sprinkler would work fine. Today I put a dart through a 2x4 at 140 psi.

[POLAND_SPUD]

my answer is.... 3/4 QEV

forget about sprinkler valves QEVs are the way to go.... oh yeah and notice the fact that 3/4" QEVs are only a little bit more expensive than 1/2" ones..

[LCTChamp]

Sorry I didn't reply sooner, but I've been busy.

Psycix the metal construction doesn't really matter like I said in the original post I can only go to 100psi.

[Ragnarok]

I was about to respond with a link to some tests that were done on Spudtech's forums between these two valve sizes, but the archive seems to have done a runner... link's dead.
The QEV won out by a pretty large margin though.

If I were you, I would seriously consider Poland_Spud's recommendation. A 3/4" QEV will be an even better choice.

[Gippeto]

If you're going to buy a valve, assuming that the costs locally are near each other or not of concern (When does that ever happen?) I would say, get the qev.

It will have a wider range of applications (for future re-use) than the sprinkler valve, and you won't have to mod it either.