High pressure hand pumps

[john bunsenburner]

I saw an artical about high pressure hand pumps on this website http://www.pyramydair.com/site/articles/hand-pump/. I was wondering if this would be an alternative to using bulk tanks? I am unsure if the price is worth it but the out put seems remarkable and having 3000psi at hand any time of the day, without having to buy bulk tanks would be really great. Has anyone here tried theses pumps? Do you think it would take too long to fill my chamber? I thank every one in advance for all comments and advice. (If there was an earlyer post on this then please tell me, i did a quick search but did not find anything.)

[Ragnarok]

Not really, those things push only tiny amounts of air - it would take ages and lots of effort to fill.

And as I said earlier - you shouldn't really be messing with thousands of psi until you've got good experience handling a few hundred.

Besides, few cannons will need that kind of pressure. Pump 300 to 500 psi into a cannon (but it should be noted, even that will require care), and the power will be more than good enough.

[jackssmirkingrevenge]

Not really, those things push only tiny amounts of air - it would take ages and lots of effort to fill.

Indeed, for the price you're better off investing in a SCUBA tank.

[far_cry]

ok
if you have a pcp rifle is great to buy like this pump
in that pump you will need 5 min to fill 1 liter of hpa

so if you have a canon i dont recomnded you to buy

[psycix]

Attach an electric motor to do the time-consuming work for you and you've got yourself a nice high pressure (very low flow) compressor.

Could be nice to fill up scuba tanks overnight.

[john bunsenburner]

No, it can only run for 5mins, then it has to cool down. But i guess it would be fine for filling my really small chamber with 300-500psi pressure or so?, i can get like 100-200psi with a normal hand pump and then i do the rest with this pump. Tell me if there are any flaws in my little idea. Oh and is the price reasonable? 200-400$ for a high pressure, low flow pump? Or should i just stick with bulk tanks(30liters for 30$ at 200bar pressure+ 150$ for a reg)


Edit: Would it be possible to build a hand pump like this for less. Did any one try doing that(and i mean a hand pump with an out put of up to 200bar). Does any one have a diagram of such a pump, I guess i could just rebuild a pump if i have a diagram...

[Brian the brain]

They have been built, a number of them
I built one and took ik up to 79.9 bar

At 80 the checkvalve blew, shooting the handle up to my mouth, breaking my upper jaw and nose.

Wasn't too bad really...I never went to a doctor..

Everything was still in place..
A bit wobbly, but who cares..
Healed up nice..

[john bunsenburner]

What piston diameter would i need to get... lets say 100bar?

[Sticky_Tape]

1mm?

[john bunsenburner]

I just did some calculations:


1mm=0.3937inches

100bar= 1500psi

1pound=0.4536kg


now: 0.3937*1500=590.55*0.4536=268

Meaning i would need 268kg of force to compress air to a pressure of 100bar with a piston diameter of 1mm. due to the fact that i only weigh 65kg that is impossible. And if i make the piston diameter much smaller it would take forever. So i cam up with the following: I could attach a lever to the end of the piston rod and then go from there, like that i could get the job done in a normal amount of time and i will not need to jump around on the piston rod to pressurize it.

But how long would the lever have to be?
and
What material should I use for the pump, will copper do or do i need something stronger?

[far_cry]

1mm?

and you still have worng calculations dude

I just did some calculations:


1mm=0.3937inches

100bar= 1500psi

1pound=0.4536kg


now: 0.3937*1500=590.55*0.4536=268

Meaning i would need 268kg of force to compress air to a pressure of 100bar with a piston diameter of 1mm. due to the fact that i only weigh 65kg that is impossible. And if i make the piston diameter much smaller it would take forever. So i cam up with the following: I could attach a lever to the end of the piston rod and then go from there, like that i could get the job done in a normal amount of time and i will not need to jump around on the piston rod to pressurize it.

But how long would the lever have to be?
and
What material should I use for the pump, will copper do or do i need something stronger?

WHAT the hell you come with thos calculations . 1mm piston this is an ant penis
i hade made a hand pump with piston diameter 2cm . i get 700 psi. this is it . the calculations for this piston diameter sayd that i can get 28 bars but i get 48 bars
http://www.spudfiles.com/forums/viewtop ... tml#206349

and you can build a high pressure hand pump and in the same time high flow
look for my idia
http://www.spudfiles.com/forums/viewtop ... tml#206454

[john bunsenburner]

I forgot i would have to take the piston area, let me recalculate to see what the maximum diameter would be for me:

I weight 65kg=143pounds

143/1500=0.1inch

0.1*2.54=0.254cm

That means the maximum area for my weight to get 100bar is 2.5mm. This time im pretty sure that i am correct. If i make the pump cylinder 60cm long then the volume would be 150cm cubed. Now my chamber is 25cmlong and has a diameter of 4 so the volume is 314cm cubed. If i use my pump to pressureize the chamber then it would take 420 pushes and pulls to get my chamber to 100bar. That is far too much, so i think it would be nesasary to either build a two or three stage pump or to add a lever to the pump and increse the surcafe area of my piston. Tell my if my calculations are wrong but i am pretty sure.


I researched into levers and found some formulas, using those i made a plan for my lever:

The fulcrum is 5cm away from the pump. The other side is 140cm long. The piston size will be 2cm. Like that i need a force of 16kg to push the lever at 100bar and i will need 52 pushes and pulls to filll my chamber to 100bar. I am fairly sure the calculations are correct.

[scavies]

Whoa. I'm intrgued. How much mechanical advantage mechanisms must be in there to get such a high pressure. I know that with a pellet rifle, you have a decent lever working on your side. That's cool.

Anyway, using a pump is really good to build massive pecs if you use it enough. To save the money, I would say get it unless you are planning to be a paintball or airsoft player.

~Scavies

[Ragnarok]

Um, maths fail.

1mm=0.3937inches

That would be 1cm = 0.3937" and 100 bar = 1450 psi

now: 0.3937*1500=590.55*0.4536=268

No, you can't feed a diameter into that equation, you need an area.

Area of a circle is Pi * radius², OR Pi * Diameter²/4

The area of a 1cm circle is 0.122 sq. in.

Feeding that in again:
0.122*1450 = 176 lbs.
176 lbs = 80 kg.

With a pump, you can usually make up a bit more "effective weight" by jumping down on to it - but it needs to be very well built for that.

However, I still VERY strongly suggest you stop considering 100 bar pressures at this time, especially seeing the number of questions and errors you're currently making.

The materials to contain those pressures are expensive, and you should really work at 10 to 20 bar launchers for some time before progressing beyond. Even I'd be wary of 100 bar, and I've got lots of experience with "mid range" high pressure.

[john bunsenburner]

Look, i redid my calculations if you would look at the second post. And i am not planing to use 100bar, i am more aiming for around 50, but maybe it will be useful one day and i will regret not having build a stronger pump, thurther more i should use something that will with stand three times as much pressure as i am planing to use so even when using around 50 bar i should really use materials rated to 150bar(if my sources are reliable that is). If you expect the average 8th grader to even think this far then you surely do not spend time with 13-15year olds. It is really just an idea. I will make some more diagrams, i will work on a lever, when i am done i will tell you how it went. It would be really great if some one could tell me what material would withstand such pressures. Thank you for your help, The pump should be finished with in a month.