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 43 users online :: 4 registered, 0 hidden and 39 guests


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

Registered users: 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

Qdv question

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

Qdv question

Unread postAuthor: fenrir » Sat Jan 11, 2014 4:53 pm

Just a quick question: is it possible for the front oring of a qdv piston to blow off at high pressure? How can this be prevented?
  • 0


fenrir
Specialist
Specialist
 
Posts: 47
Joined: Tue Jul 30, 2013 10:31 am
Reputation: 0

Re: Qdv question

Unread postAuthor: jean » Sat Jan 11, 2014 8:32 pm

yes the o-ring can blow off.
there are ways to prevent.
use thick string diameter o-rings
use rubber washer instead of o-rings
cutting slots in the way tech did it on his qdv
jean
  • 0


jean
Staff Sergeant
Staff Sergeant
 
Posts: 125
Joined: Thu Dec 13, 2007 12:23 pm
Reputation: 0

Re: Qdv question

Unread postAuthor: fenrir » Sun Jan 12, 2014 12:42 am

Thanks, but what's a "thick string diameter oring" ?
  • 0


fenrir
Specialist
Specialist
 
Posts: 47
Joined: Tue Jul 30, 2013 10:31 am
Reputation: 0

Re: Qdv question

Unread postAuthor: jackssmirkingrevenge » Sun Jan 12, 2014 3:22 am

He means a fat o-ring is better than a thin one :)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Re: Qdv question

Unread postAuthor: tigerblues28 » Sun Jan 12, 2014 2:18 pm

Yes, what jack said.

You could always epoxy them to your pistons or washers like I did.

My first *valve* I ever made was a quick dump valve, and with a home depot near by I was able to make it with readily available bolts, washers, and o rings.

Nick
  • 0

User avatar
tigerblues28
Staff Sergeant
Staff Sergeant
 
Posts: 104
Joined: Mon Apr 01, 2013 12:56 pm
Country: United States (us)
Reputation: 3

Re: Qdv question

Unread postAuthor: Technician1002 » Mon Jan 13, 2014 8:03 pm

What do you consider "high pressure"? One of my early cannons using an o ring used to launch the ring at about 60 PSI. To prevent that, I went to the ported design, so the O Ring was simply too big to fit between the side of the piston and the ported cylinder. With the new design, I have never lost an O ring. Due to my compressor capacity, I have not tested above 100 PSI. Look in the links in my sig to see the port design that holds the rings in place. Part of the ring may pop out of the groove, but once open and unable to come off, it drops back into place.

The bars between the ports prevent the o ring from blowing off the end. Make sure the space between the cylinder and piston is very small so the o ring can't fit between them.
Image

I filed and sanded the edges of the ports so there are no sharp edges that could cut the o ring.
Image
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'