Pneumatic Air pressure

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
KingKyro
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Sat Sep 25, 2010 11:50 am

I just built my first Pneumatic gun and i was wondering what are the warning signs if any that i need to be aware of so i don't put to much air pressure in my chamber.
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urgle the danish cow
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Sat Sep 25, 2010 11:52 am

if its pvc read the pipe to be extra safe and if you are using a ball valve read the valve for max psi
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Gun Freak
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Sat Sep 25, 2010 11:58 am

We need to know what kind of materials it is made out of. PVC, if sch 40, is normally used at about 100 psi. Sch 80 is rated higher and can even be used in low mix hybrids. If it is metal, like galvanized pipe nipples, then it will be good at I'd say a max of 800 psi but I wouldn't push it higher. So and pictures and/or details of the gun would help us answer your question...
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KingKyro
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Sat Sep 25, 2010 12:20 pm

here is a few picks of the chamber and valve assembly. i didn't include the barrel cause i made it interchangeable, all my PVC pipes are pressure rated.
My downfall is the end cap, coupling's and other attachments i had to buy didn't say if they where pressure rated or not.
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my modded 1 inch automatic inline sprinkler valve
my modded 1 inch automatic inline sprinkler valve
here is my pressure gauge that reads up to 160 psi, tire fill valve and pressure release valve
here is my pressure gauge that reads up to 160 psi, tire fill valve and pressure release valve
the chamber is made from a 1' long piece of 3" sch 40 pvc the is pressure rated to 260 psi
the chamber is made from a 1' long piece of 3" sch 40 pvc the is pressure rated to 260 psi
here is the full chamber valve assembly
here is the full chamber valve assembly
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Gun Freak
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Sat Sep 25, 2010 12:40 pm

With that way you drilled into a single layer or pvc three times, I would only trust this launcher up to 100 psi. Some people may suggest even lower :D How high have you been using it?
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clemsonguy1125
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Sat Sep 25, 2010 12:40 pm

The only problem I see is that you tapped the gauge into a single layer of pipe. If not for that I would say 80 PSI, but since you did personally I would rebuild it but at 30 you MAY be safe. Other than that nice, clean first pneumatic.
Edit-Gen Freak beat me to it but trust me, 100 PSI is not a good idea
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Technician1002
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Sat Sep 25, 2010 1:07 pm

Very good performance can be had if you didn't use a small restrictive valve between the chamber and barrel. Best performance is had when the valve is at least as large as the barrel. A 1.5 inch valve will out perform a 1 inch valve by about double. A 2 inch valve is often cost prohibitive. Price skyrockets with larger sizes.
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Sat Sep 25, 2010 1:12 pm

@Tech, AFAIK, 1.5" sprinkler valves are not all that common.
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Technician1002
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Sat Sep 25, 2010 2:36 pm

@ Gun Freak, I must be lucky. One store near hear even has 2 inch for about $80.
Last edited by Technician1002 on Sat Sep 25, 2010 6:56 pm, edited 1 time in total.
KingKyro
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Sat Sep 25, 2010 2:45 pm

@ tech, i had to order the 1" valve off the internet cause i couldn't find them in any stores around me. i tried Lowes, home depot and a few others. as for the gauge i had wondered if re doing the chamber so the gauge goes through the end cap and inner PVC would be better but wasn't sure. so far Ive had it up-to 60psi using a bike pump, didn't hear no leaks or anything, all i noticed is how hard it got to pump at that point. if i make the chamber shorter when i re-build it will that affect the amount of pressure i can use?
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saefroch
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Sat Sep 25, 2010 6:31 pm

No, shortening the chamber will not affect the level of pressure the pipe can take. It will affect performance though.
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Technician1002
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Sat Sep 25, 2010 7:03 pm

KingKyro wrote:@ tech, i had to order the 1" valve off the internet cause i couldn't find them in any stores around me. i tried Lowes, home depot and a few others.
This is strange. My local Home Depot has them in the Irrigation isle. Their online website lists several models that are in your local store and not for online purchase.

Model 57101 and 57100 on the page below indicates this. Don't look in the plumbing section. Check the irrigation isle for the yard and garden.
http://www.homedepot.com/webapp/wcs/sto ... ogId=10053

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KingKyro
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Sat Sep 25, 2010 7:44 pm

This is what confused me tech, i can easily find the valve on the company websites but they didn't have them for in store sale. I even had manager's looking for me in the isle's as well as on there computer's.they all came back the same online purchase only. maybe its a Pennsylvania thing i don't know.
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maverik94
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Sat Sep 25, 2010 9:48 pm

This is strange. My local Home Depot has them in the Irrigation isle. Their online website lists several models that are in your local store and not for online purchase.
My local Home depot doesn't carry sprinkler valves either. I just order mine from Amazon.com :)
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Technician1002
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Sat Sep 25, 2010 11:49 pm

I wonder if they don't carry them in locations that are always wet and humid and don't use irrigation.
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