Login    Register
User Information
We are a free and open
community, all are welcome.
Click here to Register
Who is online

In total there are 76 users online :: 5 registered, 0 hidden and 71 guests

Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: 3fenders, Bing [Bot], farcticox1, Google [Bot], Google Adsense [Bot] based on users active over the past 5 minutes

The Team
Global Moderators
global_moderators.png CS

Piston Valve or Quick Dump Valve ?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.

What should I use?

Quick Dump Valve
Coaxial Piston Valve
Total votes : 5
  • Author

Piston Valve or Quick Dump Valve ?

Unread postAuthor: Ranger » Fri Jun 11, 2010 11:24 am

For my next project I want to build a big Gun, 2" bore and 3" chamber. All this time I had been planning on making a Coaxial Piston Valve cannon, but then I found this
http://www.spudfiles.com/forums/quick-d ... 17858.html
Technician1002's marshmallow cannon and his T-Shirt cannon. I like both designs but I'm trying to figure out which one would be better, I'm going for distance and power so I want the better of the 2 designs.

I cant figure out which one would be better, it would make sense that the coax would have the highest flow rate (since its opening the entire back of the pipe not just little ports on the side) but the QDV could be better becuase of a quicker opening time (or someting that I havent thought of)

Any thoughts on the subject?
  • 0

Posts: 78
Joined: Thu May 27, 2010 10:01 pm
Location: Texas
Reputation: 0

Unread postAuthor: Technician1002 » Fri Jun 11, 2010 11:32 am

Those little ports have more cross section area than the pipe it feeds into. Check the details.

3 ports 1 inch by 2 inch is 2 square inches per port. That is 6 square inches total. The cross section area of the 2 inch pipe is about 1/2 that area at 3.14 square inches.

The t shirt launcher was launching into the 300 section (nosebleed seats) on only 30 PSI.

The Coaxial piston is easier to build. The QDV takes more work getting a good sealing surface and it seals in 2 places so piston construction is much more complicated This is not a project for a first time builder.

The ABS version instead of the steel version is much less difficult to construct. Use an adequate bumper if making it from PVC. The piston slams open hard.

My most recent damage photo is from today. An empty pop can was launched into a steel plate.

May I recommend a 4 inch chamber instead of 3 inch? My ABS cannon was constructed this way.

limited power is not an issue.
  • 0

Last edited by Technician1002 on Fri Jun 11, 2010 2:36 pm, edited 1 time in total.
User avatar
Chief of Staff
Chief of Staff
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Gun Freak » Fri Jun 11, 2010 2:10 pm

I recomend a co-ax because of the ease of construction and how little parts you need. I have never made a QDV myself, but it really depends on the tools you have to work with and the amount of work you plan to dedicate to it.
  • 0

OG Anti-Hybrid
One man's trash is a true Spudder's treasure!
Golf Ball Cannon "Superna"M16 BBMGPengunHammer Valve Airsoft SniperHigh Pressure .22 Coax
Holy Shat!
User avatar
Gun Freak
Lieutenant General
Lieutenant General
Posts: 4976
Joined: Mon Jan 25, 2010 4:38 pm
Location: Florida
Country: United States (us)
Reputation: 14

Return to Pneumatic Cannon Discussion

Who is online

Registered users: 3fenders, Bing [Bot], farcticox1, Google [Bot], Google Adsense [Bot]

Reputation System ©'