Home made high pressure pump

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
SaskAlex
WRA2 Member
WRA2 Member
Posts: 238
Joined: Tue Apr 07, 2009 2:36 pm

Home made high pressure pump

Post by SaskAlex »

Well, in another thread of mine I mentioned my home made hand pump, and a few people expressed some interest. I'm at school so I can't upload any pictures or anything, but I'll do my best to describe it.

The barrel of the pump is made of 1/2" drawn copper tubing. Check out http://www.copper.org/Applications/plum ... ble3a.html for working pressure ratings. The tubing actually has an inner diameter of around 9/16", which is almost exactly a half of the inner diameter of my bike pump. I can get about 200 psi out of my bike pump, so I should be able to get 800 with this home made one. I don't ever plan to go that high, though.

I made the plunger out of pvc turned on the lathe. I use some 1/2" O.D. steel pipe to connect the plunger to the handle. If you've ever taken a bike pump apart, you'll know that the seal on the plunger also acts as a one-way valve. It's quite simple, but hard to explain without a picture.

The bottom of the pump is made with brass fittings. The bottom one-way valve is made with a valve stem. I'll definitely need some pictures to describe this part.

The pump works, but it takes a long time to pump anything up. One of the problems is that you need an o-ring of the perfect diameter if want it to act as a one-way valve. If you take apart the top of a bike pump you will under stand this. My o-ring is a little small, and I have to occasionally stretch it out. Sometimes it seems like it doesn't seal until I've completed a significant portion of the stroke. So far, I've used it for pressure testing, but I haven't actually launched a rocket with it yet.

Anyways, it's worth a try to make one if you can't afford those ~$200 3000psi hand pumps on the internet, or if you're like me and just like to make things on your own. If you do make one, be safe! Make sure you stay well within the ratings of your components. There is never a whole lot of energy in the pump, since it's volume is so small, but it is right between your legs.

I'll try and get some pictures up this weekend.
Randino
WRA2 Member
WRA2 Member
Posts: 19
Joined: Wed Feb 24, 2010 12:39 am

Re: Home made high pressure pump

Post by Randino »

Yes, please do put pictures up when you can. A pump like that could be a great help to a lot of us. I usually use a compressor, but a pump would be a lot easier to bring with me to parties and such. It would also give me chance to show off my ripped muscles and further impress the ladies 8)

Randy
"Neither will alone, nor strength alone will be enough."
SaskAlex
WRA2 Member
WRA2 Member
Posts: 238
Joined: Tue Apr 07, 2009 2:36 pm

Re: Home made high pressure pump

Post by SaskAlex »

Well here are the pictures. I'm not sure if I'll be doing any more high pressure work soon, but if I do I'll make a small modification to the pump. I'm going to make a new plunger piece with a regular, full groove for the o-ring. This way the o-ring will always seal with the tube. Near the top of the copper tube, I will drill a hole. When the o-ring comes above this hole, air will fill the copper tube. This will solve the problem I mentioned in my first post where the plunger only seems to seal well into the stroke. You will be creating a vacuum on the up stroke, so you are wasting some energy, but it is very little.

Alex
Attachments
Here is the pump. The hose and pump head are from a cheap old bike pump. I might have to upgrade them later.
Here is the pump. The hose and pump head are from a cheap old bike pump. I might have to upgrade them later.
DSCI0002.JPG (409.45 KiB) Viewed 201 times
There is a copper cap at the top of the copper tub. It has a 1/2" hole in it to let the steel pipe through, but prevents the plunger from coming out. It is not soldered in place. I just use electrical tape to hold it in place so I can take the pump apart easily. I can just pound a 3/8" bolt into the steel pipe. I pounded a bolt into either end, and used them to secure the handle and the plunger to the steel pipe.
There is a copper cap at the top of the copper tub. It has a 1/2" hole in it to let the steel pipe through, but prevents the plunger from coming out. It is not soldered in place. I just use electrical tape to hold it in place so I can take the pump apart easily. I can just pound a 3/8" bolt into the steel pipe. I pounded a bolt into either end, and used them to secure the handle and the plunger to the steel pipe.
DSCI0004.JPG (165.89 KiB) Viewed 201 times
Below the copper tube you can see a reducing bushing. The bushing threads into a 3/8" brass tee. A pressure gauge threads into one end of the tee, and a barbed fitting threads into the other. The bolts that are securing the tee to the bottom steel plate were supposed to be temporary, but they seem to do the job so I haven't bothered making a more secure connection.
Below the copper tube you can see a reducing bushing. The bushing threads into a 3/8" brass tee. A pressure gauge threads into one end of the tee, and a barbed fitting threads into the other. The bolts that are securing the tee to the bottom steel plate were supposed to be temporary, but they seem to do the job so I haven't bothered making a more secure connection.
DSCI0007.JPG (165.83 KiB) Viewed 201 times
This is the plunger. The o-ring can deform when you pull the handle up, letting air flow into the barrel on the up stroke.
This is the plunger. The o-ring can deform when you pull the handle up, letting air flow into the barrel on the up stroke.
DSCI0009.JPG (162.4 KiB) Viewed 201 times
DSCI0008.JPG
DSCI0008.JPG (180.35 KiB) Viewed 201 times
The PVC piece is glued over top of a valve core. The valve core acts as a check valve, preventing air from flowing back into the barrel. The valve core has a weak spring. It takes less than 20 psi to let air flow (out of the barrel, of course). The valve core has a male pipe thread end, and threads into the reducing bushing. The copper tube is a tight fit over the PVC piece and makes a seal with the o-ring.
The PVC piece is glued over top of a valve core. The valve core acts as a check valve, preventing air from flowing back into the barrel. The valve core has a weak spring. It takes less than 20 psi to let air flow (out of the barrel, of course). The valve core has a male pipe thread end, and threads into the reducing bushing. The copper tube is a tight fit over the PVC piece and makes a seal with the o-ring.
DSCI0011.JPG (86.13 KiB) Viewed 201 times
DSCI0012.JPG
DSCI0012.JPG (86.78 KiB) Viewed 201 times
User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1778
Joined: Sat Feb 03, 2007 3:24 pm

Re: Home made high pressure pump

Post by U.S. Water Rockets1 »

This is a really good illustration of how to make a homemade pump. The only things to consider is that you should make a diagram showing how the plunger and o-ring work together. Some people have never taken apart a pump so it may mot be clear how the o-ring allows air in only on the upstroke. Another thing that is important is to make sure if you solder any of the pipes together to be sure and use silver solder, because it makes a much stronger joint than other types of solder.

Nice work!
Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison
SaskAlex
WRA2 Member
WRA2 Member
Posts: 238
Joined: Tue Apr 07, 2009 2:36 pm

Re: Home made high pressure pump

Post by SaskAlex »

U.S. Water Rockets1 wrote:This is a really good illustration of how to make a homemade pump. The only things to consider is that you should make a diagram showing how the plunger and o-ring work together. Some people have never taken apart a pump so it may mot be clear how the o-ring allows air in only on the upstroke. Another thing that is important is to make sure if you solder any of the pipes together to be sure and use silver solder, because it makes a much stronger joint than other types of solder.

Nice work!

Well, if anyone is going to try something similar, I would not recommend the plunger that acts as a one-way valve. It's too hard to get right, especially with a small diameter pump. And you need to luck out and get an o-ring of the perfect size to even have a chance. I would recommend the solution I talked about in my previous post. The first sketch below illustrates that solution. The o-ring on the plunger makes a permanent seal with the sides of the barrel. On the up stroke you create a vacuum. When the plunger gets to the top of the pump (the position in the drawing) the o-ring goes above this hole and air fills the barrel for your next down stroke. I haven't tried this method yet, but I'm confident it will be far simpler and more effective than the "one way valve plunger".

The bottom sketch is supposed to demonstrate how the one way valve plungers work, for those who are really interested.
Attachments
simple plunger.jpg
simple plunger.jpg (15.22 KiB) Viewed 182 times
A plunger that acts as a one way valve.
A plunger that acts as a one way valve.
plunger.jpg (55.52 KiB) Viewed 182 times
User avatar
andicirk
WRA2 Member
WRA2 Member
Posts: 95
Joined: Thu Oct 09, 2008 1:20 pm

Re: Home made high pressure pump

Post by andicirk »

excellent thread any chance that this could get bumped or linked to the how too section
User avatar
RaZias
WRA2 Member
WRA2 Member
Posts: 751
Joined: Mon Jul 14, 2008 3:16 pm

Re: Home made high pressure pump

Post by RaZias »

Have ever tough in selling one of these pumps ?

I am interested in buying a 300 psi air pump. I hope it´s safe.
Research and Development is the soul of WR