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

In total there are 52 users online :: 5 registered, 0 hidden and 47 guests


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

Registered users: anello, Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Help with QEV valve, first time builder.

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.
Sponsored 
  • Author
    Message

Help with QEV valve, first time builder.

Unread postAuthor: loaferz » Mon Dec 24, 2007 1:35 am

So Im really excited about building my first pneumatic cannon, got all the parts together and thought I had everything working, but I'm running into some problems.

First off, let me describe my design, I am going for a portable design, so I am deciding to use a bicycle pump connected to a schrader valve in order to charge up the system.

how it should work:

1. Air is pumped in via a bicycle pump, cylinders start to charge and because the ball valve is closed, pressure on the inlet should still keep the qev closed
2. ball valve is opened, thus inlet pressure drops and all air from cylinders goes to the outlet barrel.






The problem is, that when I pump up the system, i get one pump,it charges in the tanks, then the qev discharges. I think this is because pressure is getting lost through the inlet port. Is this because of the bicycle pump? Do I need a different design? Or are QEV's not possible to run without an air compressor.

thanks,
  • 0

Attachments
spud.jpg
spud.jpg (11.69 KiB) Viewed 322 times

loaferz
Private
Private
 
Posts: 1
Joined: Mon Dec 24, 2007 1:18 am
Reputation: 0

Unread postAuthor: clide » Mon Dec 24, 2007 1:50 am

It should be possible to do with a bike pump, but you need to make sure everything is sealing well. Check all your plumbing and make sure that isn't leaking and check the fitting that hooks up to the schrader, if you can't get that fitting to seal well against the schrader you may have to cut it off and try a different kind or maybe even add a check valve between the schrader and the pilot area.
  • 0

<a href="http://gbcannon.com" target="_blank"><img src="http://gbcannon.com/pics/misc/pixel.png" border="0"></a>latest update - debut of the cardapult

clide
Donating Member
Donating Member
 
Posts: 785
Joined: Sun Mar 06, 2005 3:06 am
Location: Oklahoma, USA
Reputation: 0

Unread postAuthor: MrCrowley » Mon Dec 24, 2007 1:58 am

<A HREF="http://www.spudfiles.com/forums/viewtopic,p,123928.html#123928">My QEV cannon</a> has a similar setup to yours and works fine with a cheap shock pump I got at Wal*Mart.

The only thing that may be a problem is if your chamber is quite large you may have to pump faster to get it to seal. Maybe try a pump with more volume, that should fill the chamber up faster.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: MaxuS » Mon Dec 24, 2007 5:29 am

As clide said:
Put on a check valve, its most likely that when you draw air into the pump on the upstroke that its lowering the pressure slightly inside the pilot volume. A check valve will keep air from escaping whilst pumping.
  • 0

User avatar
MaxuS
Sergeant Major
Sergeant Major
 
Posts: 198
Joined: Sun Sep 02, 2007 5:11 pm
Reputation: 0

Return to Pneumatic Cannon Discussion

Who is online

Registered users: anello, Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'