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 51 users online :: 5 registered, 0 hidden and 46 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

DIY HPA route? (Diaphragm pump?)

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

Unread postAuthor: kenbo0422 » Tue Nov 24, 2009 9:55 pm

kenbo0422, that is a great idea. Now so I don't get any exercise, biggie size it?


You put it in a frame and pump it with a motor.
  • 0

User avatar
kenbo0422
2nd Lieutenant
2nd Lieutenant
 
Posts: 201
Joined: Mon Oct 06, 2008 7:33 am
Location: East Tennessee
Reputation: 0

Unread postAuthor: iknowmy3tables » Tue Nov 24, 2009 11:03 pm

kenbo0422 wrote:
kenbo0422, that is a great idea. Now so I don't get any exercise, biggie size it?


You put it in a frame and pump it with a motor.

but what about the clearances the dead space, to reduce dead space you need near zero clearance at the extreme of the piston stroke, for this reason many diaphragm pumps use solenoids

it just occurred to me that most of the high pressure diaphragm compressors you mention are multi stage, in order to make it multistage both sides of the diaphragm must have the same starting pressure at the beginning of each stroke, which doesn't seam to be the case
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: Technician1002 » Wed Nov 25, 2009 12:59 am

A diaphragm pump is used to pump light gas because any tiny leak such as past piston rings is a huge leak to a light gas. Normal rings on a piston simply don't contain Helium or Hydrogen at high pressure. That is the only reason they use a diaphragm. The lower efficiency is a trade off from the low efficiency from high blowby.

There is no reason a pump has to have the same pressure on both sides of the diaphragm. A cylinder can run fine with the crankcase at 1 atm and the inlet at 10 bar and exit at 40 bar.

Only the first stage needs to drop below 1 atm to draw in past the valves.
  • 0

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

Unread postAuthor: kenbo0422 » Wed Nov 25, 2009 5:43 am

The systems on the submarines I was on had a six stage pump for 6000psi. The cylinders were such that the push rod on one side diminished the volume of the stroke while the other side was open. Each stage progressively started out smaller until the last stage, which ported out to a storage bank. It was then regulated to about 2000psi to keep pressure on the primary loop of the reactor so as not to allow the water to boil around the fuel rods.

By exhausting into a smaller volume with each stage, you kind of make up for the 'dead' space, since the gas has no choice but to be compressed.

Edit: The pressure differential across each stage is what you want to consider. Orings, for example can block just over 1000 psi, if you were to want a higher difference, you would use more orings. If you want the strokes to be easy on your arm, make the pressure differential lower. Pumping from 15 to 50 psi is almost as easy as pumping from 1515 to 1550 psi with the exception of the seals pushing on the sides.
  • 0

User avatar
kenbo0422
2nd Lieutenant
2nd Lieutenant
 
Posts: 201
Joined: Mon Oct 06, 2008 7:33 am
Location: East Tennessee
Reputation: 0

Unread postAuthor: iknowmy3tables » Wed Nov 25, 2009 7:03 am

Technician1002 wrote:There is no reason a pump has to have the same pressure on both sides of the diaphragm. A cylinder can run fine with the crankcase at 1 atm and the inlet at 10 bar and exit at 40 bar.

a multistage compressor wouldn't have such a format (unless there were two alternating second stage cylinders connected to the crank shaft), assume the input is 100psi above atmospheric pressure and the output is 400psi atmospheric pressure and the crossectional area of the piston is 1inch^2; so in this system the force required to start pushing the piston is 100pounds force and towards the end of the stroke it is 400pounds force, with such a design you might as well not use multiple stages, what is supposed to happen is for the peak mechanical force to be based on the pressure difference between the input and output
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: POLAND_SPUD » Wed Nov 25, 2009 7:09 am

Pumping from 15 to 50 psi is almost as easy as pumping from 1515 to 1550 psi with the exception of the seals pushing on the sides
tha'ts the reasoning I used when I suggested that the air input of a fridge compressor could be fed with compressed air

Apparently, tech and jimmy thinks it's wrong and I must say that their explanation seems logical

sorry I have to find a thread on it
EDIT I found them
http://www.spudfiles.com/forums/two-fri ... 18219.html
http://www.spudfiles.com/forums/compressor-t18078.html
http://www.spudfiles.com/forums/fleebay ... rt,15.html
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: jmadden91 » Wed Nov 25, 2009 7:47 am

I would personally look into the workings of scuba compressors like this one. Are they scroll, diaphragm, piston?

Image
  • 0

User avatar
jmadden91
2nd Lieutenant
2nd Lieutenant
 
Posts: 246
Joined: Thu May 07, 2009 6:03 pm
Location: Queensland, Australia
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: psycix » Wed Nov 25, 2009 7:50 am

I believe most are two-stage piston or else scroll.

Pumping from 15 to 50 psi is almost as easy as pumping from 1515 to 1550 psi with the exception of the seals pushing on the sides

Only if the crankcase is under 1500 psi of pressure, and then the seal is the same.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: kenbo0422 » Wed Nov 25, 2009 8:00 am

I believe those are piston compressors, multi staged, I think possibly with an unloader mechanism rather than a pop off valve. The one pictured looks like it does have a pop off valve, though.
  • 0

User avatar
kenbo0422
2nd Lieutenant
2nd Lieutenant
 
Posts: 201
Joined: Mon Oct 06, 2008 7:33 am
Location: East Tennessee
Reputation: 0

Unread postAuthor: twizi » Wed Nov 25, 2009 9:08 am

what about those presure amplifers if seen them at paintball the put a 100psi in and it make a poping soud then u add low presure co2 and it compreses it to 900psi. you coud do this with air and amplify even more.
  • 0

dont play with airsofter with 1000$ gun and play with a 5 dollar pair of glasses
User avatar
twizi
Colonel
Colonel
 
Posts: 511
Joined: Thu Nov 27, 2008 9:04 pm
Location: up yours
Reputation: 0

Unread postAuthor: POLAND_SPUD » Wed Nov 25, 2009 9:43 am

http://www.haskel-usa.com/gas_booster.htm

@pimpman
that's what I had in mind... I don't think you can build a simpler/cheaper one...

also I don't expect that that traditional compressor design will become common as a HPA pump for future spudders

just think about fridge compressors.. they are as cheap and easy to build as possible but there are not as popular as one would expect them to be (IDK the exact number.... there are 10 maybe up to 30 of them on this site??)
  • 0

Attachments
homemade pressure amplifier.PNG
homemade pressure amplifier.PNG (22.24 KiB) Viewed 1085 times
Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: kenbo0422 » Wed Nov 25, 2009 9:52 am

Pressure amplifiers work by using a large duplex piston with low pressure ( your lp air) to move a smaller piston which is supplied by the same air pressure. The larger surface on the driving piston allows it to push the smaller piston to a much greater pressure ( Pressure = Force (lbs) x area).

The discharge from the larger pistons goes into the intake of the smaller pistons and some is bled off with an upstream regulator or blow off valve in some cases. It cycles like a locomotive piston arrangement, so you 'pump' to a higher pressure using the supply air. There doesn't seem to be any reason why you couldn't cascade these to achieve even higher pressures unless the mechanism isn't made for it.

EDIT: http://www.mcmaster.com/#pressure-amplifiers/=4nnvgh

They aren't cheap!
  • 0

User avatar
kenbo0422
2nd Lieutenant
2nd Lieutenant
 
Posts: 201
Joined: Mon Oct 06, 2008 7:33 am
Location: East Tennessee
Reputation: 0

Unread postAuthor: john bunsenburner » Wed Nov 25, 2009 11:13 am

A pressure multiplier is an idea I have toyed with for a while. They seem expensive to buy but cheap to build if one has a lathe. I know Ragnarok has an idea for a mech. for these.

Really the problem is that since there is no fly wheel to push the piston back you need to make a mechanism todo so, that would most probably be the trickiest part, esp. if you want to cost down and pressures reasonably high.

Another question is how efficient they are, after all to get the piston back into it's place one needs to relieve the pressure on the big bore side, or over come it, doing this without venting may provide tricky.

Anyway, i think a pressure multiplier(PM from now on) is a better idea than a multi-stage pump, as a DIY source of HPA.
  • 0

"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
User avatar
john bunsenburner
Major General
Major General
 
Posts: 1446
Joined: Sun Oct 19, 2008 5:13 am
Reputation: 0

Unread postAuthor: POLAND_SPUD » Wed Nov 25, 2009 11:41 am

Really the problem is that since there is no fly wheel to push the piston back you need to make a mechanism to do so
yo can either use
2 DCV valves that would switch the air flow when the air cylinder extends and retracts

or just use a timing circuit ( fully pneumatic circuit )

also I don't think there is any need for machining... it might be useful to build the check valve and maybe the piston of hte pump... but you might as well use a ready made PCP pump
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: john bunsenburner » Wed Nov 25, 2009 12:03 pm

meh, a pcp pump is 200-400$, the stock i would need to make that is under 100$.
  • 0

"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
User avatar
john bunsenburner
Major General
Major General
 
Posts: 1446
Joined: Sun Oct 19, 2008 5:13 am
Reputation: 0

PreviousNext

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'