I was making a pump and was wondering how badly the dead space would impact performance? It is currently in a working state but not complete enough to do pressure tests..
I also need a way to make a check valve, I currently have a washer screwed into the threads of the T and epoxied as well as the coupling epoxied and screw tight into it. I was thinking maybe a bolt on a spring with one of those rubber grommet nuts on the end that meets up with the washer?
Making a pump....
- Mr.Tallahassee
- Specialist 3
- Posts: 364
- Joined: Sun Jul 10, 2011 2:35 am
You could probably make a check valve with some copper fittings. A 1/2''-1/4'' copper bushing put in backwards after being polished should work. Just put in a washer stack with a sealing surface on it and a groove cut to let the air flow past the washers better. Just make sure not to cut too far so that the face seals.
- Attachments
-
- check valve.JPG (31.91 KiB) Viewed 4713 times
- Crna Legija
- First Sergeant 2
- Posts: 2333
- Joined: Sun Jul 20, 2008 5:14 am
- Location: australia
I personally would not make a check valve, its is very dangers if it fails under pressure, the pump will turn into a air cylinder and shoot the handle straight up. BTB knows too well what its like, his broke his jaw when the handle smacked him in the head.
'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson
Add me on ps3: wannafuk, 8/11/11 cant wait
--Homer Simpson
Add me on ps3: wannafuk, 8/11/11 cant wait
-
- Staff Sergeant 3
- Posts: 1769
- Joined: Mon Mar 21, 2011 5:41 pm
One thing to do, assuming you live in the states, is goto lowes or home depot and buy a check valve, they are "rated" to 200 psi, but I am assuming you can use them higher than that.
The female-female check valves from mcmaster aren't all that expensive, and there are some rated to 1,000psi. By inserting a little spacer at the end of the pump before the check valve, you can get the dead volume down pretty far.
Mcmaster check valves are a pretty good price just as saefroch mentioned, and will probably last you a long time. I very much recommend it.
Now that I have been re-enlightened to this idea, I think I will finish my pump (One emoticon i havent used yet)
Now that I have been re-enlightened to this idea, I think I will finish my pump (One emoticon i havent used yet)
4SPC, My 4" piston 3" porting cannon
Memo:
Fix up copper cannon
Fix up 4SPC
Start Stirrup pump
Start Toolies piston bazooka
Memo:
Fix up copper cannon
Fix up 4SPC
Start Stirrup pump
Start Toolies piston bazooka
- Lockednloaded
- Staff Sergeant
- Posts: 1566
- Joined: Thu Sep 03, 2009 9:38 pm
- Location: Texas, USA
- Been thanked: 6 times
I'd really recommend saving for the PCP pump, I have one and I love it, not only can you charge your guns to 3600psi, but also you can charge HPA tanks
I love lamp
Do they have standard threads on the hoses that you can use to swap out for standard connections (like regular disconnects, etc) ?Lockednloaded wrote:I'd really recommend saving for the PCP pump, I have one and I love it, not only can you charge your guns to 3600psi, but also you can charge HPA tanks
- Crna Legija
- First Sergeant 2
- Posts: 2333
- Joined: Sun Jul 20, 2008 5:14 am
- Location: australia
IIRC its 1/8 npt on most pumps, so yeah its a stranded size but your better off using high pressure the high pressure one the come with it because they disconnect easier and wont wear out quicklysco77 wrote:Do they have standard threads on the hoses that you can use to swap out for standard connections (like regular disconnects, etc) ?Lockednloaded wrote:I'd really recommend saving for the PCP pump, I have one and I love it, not only can you charge your guns to 3600psi, but also you can charge HPA tanks
'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson
Add me on ps3: wannafuk, 8/11/11 cant wait
--Homer Simpson
Add me on ps3: wannafuk, 8/11/11 cant wait
- Lockednloaded
- Staff Sergeant
- Posts: 1566
- Joined: Thu Sep 03, 2009 9:38 pm
- Location: Texas, USA
- Been thanked: 6 times
I made a simple adaptor with a male PCP QD in a 1/8"-1/4" bushing to a female 1/4" QD
I love lamp
- Technician1002
- Captain
- Posts: 5189
- Joined: Sat Apr 04, 2009 11:10 am
Air compresses. The dead space can contain a large portion of your compressed air which won't go out the check valve then re expand in the cylinder so the pump will not take in more air to pump. The pressure you can get with a single stage pump is limited by the amount of dead space.wondering how badly the dead space would impact performance?
Here is an example. Let's say you have a pump where the dead space is the same volume as the displacement of the piston. On air intake, the cylinder will contain 1 Atm of pressure. On the compression stroke, air is pumped out the check valve. As the chamber pumps up to pressure some of the air is compressed in the dead space and then re-expands so as the chamber comes up to pressure, less air is pumped on each stroke. When the chamber is up to 2 Atm (about 15 PSI), the pump will no longer pump air. It will compress the air in the pump to 15 PSI and that will re-expand in the cylinder instead of being pumped out to the chamber. The smaller the dead space the higher the pump is able to pump.
I just went and ordered a PCP pump and a couple male fittings for guns... I will probably also get a fridge compressor when I get a hold of one for free but hopefully the 3 stage pcp pump will be able to reach 300-500PSI fairly quickly on small 20~ CI chambers.