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 79 users online :: 5 registered, 0 hidden and 74 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

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

The Team
Administrators
Global Moderators
global_moderators.png CS

How piston valves are measured.

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

How piston valves are measured.

Unread postAuthor: Technician1002 » Thu Apr 16, 2009 3:29 pm

When searching to compare performance of 2 inch piston designs with my 2 inch quick dump valve, I found many 2 inch valves are really 1 or 1-/2 inch and I needed to compare to the 3 inch valves with a 2 inch barrel.


I've noticed a trend on spudfiles that piston valves are measured by the diameter of the piston The rest of the industry measures their valves by the diameter of the valve orifice. For example a 3/4 inch QEV has a 3/4 inch port. The piston is larger. Is there a reason we don't use port size here?
  • 0

Last edited by Technician1002 on Thu Apr 16, 2009 4:13 pm, edited 1 time in total.
User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Biopyro » Thu Apr 16, 2009 3:35 pm

Not really, just that often when someone makes a valve, they'll be thinking "hmm 50mm piston so it's a 50mm piston valve" sgort and others selling piston valves do list them by port size though. I think it tends to be just a common mistake as opposed to a set protocol. Lots of the more experienced spudders will correctly classify their valves though.
  • 0

Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety. -Benjamin Franklin
User avatar
Biopyro
Colonel
Colonel
 
Posts: 656
Joined: Fri Aug 04, 2006 5:32 am
Location: UK
Reputation: 0

Unread postAuthor: MrCrowley » Thu Apr 16, 2009 3:45 pm

I just do it through habit as I was probably confused back in the day when there was no set 'protocol'.
  • 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: King_TaTer » Thu Apr 16, 2009 4:15 pm

Yeah I have noticed that over the duration of my time here. If I were you I would construct a "2 inch piston" yourself to see if it really stacks up against your quick dump valve. This would allow for consistency and accuracy when testing the two valves.
  • 0

Materials links:
<a href="http://www.discounthydraulichose.com/">Discount Hydraulic Hose</a>
<a href="http://www.buyfittingswholesale.com/#">Buy fittings wholesale</a>
<a href="http://www.flexpvc.com/">Flex PVC</a>
<a href="http://www.murrayequipment.com">MEI
</a>
User avatar
King_TaTer
1st Lieutenant
1st Lieutenant
 
Posts: 265
Joined: Fri Nov 17, 2006 6:14 pm
Reputation: 0

Unread postAuthor: Brian the brain » Thu Apr 16, 2009 4:32 pm

I always refer to the port size.

The only reason I could see to do otherwise is to brag.

So I quess I have a 2 inch porting 3 inch pistonvalve...
  • 0

Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3494
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Country: Netherlands (nl)
Reputation: 29

Unread postAuthor: Hotwired » Thu Apr 16, 2009 5:00 pm

There is no standard.

But what is generally said is:

X inch piston valve with Y porting.

Which is more telling than just one number.


You could for example have a 3" piston but only 2" of porting, that would not be the same as a 2" piston with 2" of porting.
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Unread postAuthor: Technician1002 » Thu Apr 16, 2009 5:54 pm

Hotwired wrote:There is no standard.

But what is generally said is:

X inch piston valve with Y porting.

Which is more telling than just one number.


You could for example have a 3" piston but only 2" of porting, that would not be the same as a 2" piston with 2" of porting.


I've noticed this. Some valves are not specified by the orifice, but by the size of the pipe they connect to. I've seen this a lot in small ball valves where the actual port is smaller than the pipe. You have to watch this if you need the full diameter for flow or projectiles. :(

***EDIT***
I modified a 1 inch PVC ball valve to use as a breech loader on my marshmallow cannon. The 1 inch gum balls won't fit in the valve. :(

I grabbed the calipers. The gumballs I have are 1.02 inches and the ball valve is 0.990. So close, but no go.
They fit the barrel very nicely :D
  • 0

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

Sponsored

Sponsor
 


Unread postAuthor: Ragnarok » Thu Apr 16, 2009 7:01 pm

I personally always refer to the seat diameter of the valve, but have a habit of qualifying it like saying 1.5" porting piston valve.

The reason I do this is that as far as piston valves are concerned, while the piston's overall diameter affects opening time, the magnitude of the variations between different (well made) piston valves has minimal effect on the projectile's velocity. The seat diameter however has affects flow, which has a big effect on the projectile's velocity.

In other words, two piston valves with 1.5" porting, one with a 3" piston and the other with a 2" piston will have similar performance.
Two piston valves with a 2" piston, one with 1" porting, the other with 1.5" porting - the latter will be noticeably more powerful, assuming the barrel can support the flow.

Hence, I'm more interested in the seat diameter than the piston diameter.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: Technician1002 » Thu Apr 16, 2009 7:11 pm

King_TaTer wrote:Yeah I have noticed that over the duration of my time here. If I were you I would construct a "2 inch piston" yourself to see if it really stacks up against your quick dump valve. This would allow for consistency and accuracy when testing the two valves.


I've considered that, but currently working on a 3 inch 200 PSI valve. I'm more interested in how that performs against the 2 inch. :D
  • 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], Google Adsense [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'