SpudFiles

What is the maximum pressure that a Schrader valve can be used in a pneumatic cannon?

IOW I would like to try a Schrader valve to fill the gun an also use it as the pilot valve.

My inspiration comes from this:



Will a Schrader take 600 psi?

BoyntonStu

Well i you can find it i believe there is a thread where gippeto has tested the valve core to 7500 psi. So i do believe it will take the pressure. I have personally used them to 1500 psi with no problems

Mr.Sandman wrote:Well i you can find it i believe there is a thread where gippeto has tested the valve core to 7500 psi. So i do believe it will take the pressure. I have personally used them to 1500 psi with no problems

What kind of chuck did you use?

Was it a no-leak or a conventional chuck?

BoyntonStu

boyntonstu wrote:

Mr.Sandman wrote:Well i you can find it i believe there is a thread where gippeto has tested the valve core to 7500 psi. So i do believe it will take the pressure. I have personally used them to 1500 psi with no problems

What kind of chuck did you use?

Was it a no-leak or a conventional chuck?

BoyntonStu

I used this ancient schrader adapter i found in my dads tool box. Rated to 3000 psi is engraved into it.

Mr.Sandman wrote:

boyntonstu wrote:

Mr.Sandman wrote:Well i you can find it i believe there is a thread where gippeto has tested the valve core to 7500 psi. So i do believe it will take the pressure. I have personally used them to 1500 psi with no problems

What kind of chuck did you use?

Was it a no-leak or a conventional chuck?

BoyntonStu

I used this ancient schrader adapter i found in my dads tool box. Rated to 3000 psi is engraved into it.

Did you hold it against the valve at 1,000 psi or was it connected?

600psi wont brake the valve.

Yeah, tested to 10000psi actually. Destroyed the sealing face of the core, but no other damage. Replaced the core and it's in use today.

Here ya go Stu;

http://www.aircraftspruce.com/catalog/l ... seneck.php

Schrader USA prt# 6116

Rated for 3000psi.

I've used a schrader as a pilot on a 1" piston but you need to have an efficient design with a tight piston and limited piston movement to ensure minimum pilot volume. Of course if your design has an airtight piston that greatly increases your chances of success.

Gippeto wrote:Yeah, tested to 10000psi actually. Destroyed the sealing face of the core, but no other damage. Replaced the core and it's in use today.

Here ya go Stu;

http://www.aircraftspruce.com/catalog/l ... seneck.php

Schrader USA prt# 6116

Rated for 3000psi.

Don,

Thanks,

Did you ever fill to 600 psi using a "regular" air chuck that you held against the Schrader?

Here's a no-leak chuck that may work:

http://www.tire-pressure-gauge.com/inde ... ucts_id=19

What do you think?

I am afraid that if I do away with the ball valve the Schrader may leak when I remove the chuck and accidentally fire the cannon.

BoyntonStu

jackssmirkingrevenge wrote:I've used a schrader as a pilot on a 1" piston but you need to have an efficient design with a tight piston and limited piston movement to ensure minimum pilot volume. Of course if your design has an airtight piston that greatly increases your chances of success.

Great work.

You got there before me, wonderful!

Have you thought of a trigger mechanism to press the Schrader?

Bravo!

BoyntonStu

I have got 300psi with a but i had to push it keep it on.i use QD now its ezyer. Air you using co2 or air.

boyntonstu wrote:Have you thought of a trigger mechanism to press the Schrader?

Usually the first bolt/screwdriver/allen key I find lying around

Closest I made to an actual "trigger" was on the original pen gun.

boyntonstu wrote:What is the maximum pressure that a Schrader valve can be used in a pneumatic cannon?

IOW I would like to try a Schrader valve to fill the gun an also use it as the pilot valve.

My inspiration comes from this:



Will a Schrader take 600 psi?

BoyntonStu

This one is rated for 5000 psi

Stu, I have tried a couple of those "clip on" style chucks. They blow off at ~250psi. I use only probe style fills and threaded connections with check valves now. Trouble free.

http://www.pyramydair.com/site/articles ... d-port.jpg

Another option is these fittings used on many pcps. They have the check valve built in. For lower pressures, I'm sure you can figure how to make one from a common compressor fitting?

http://www.crosman.com/blogs/croswords/ ... shots2.jpg



The fitting I linked you to previously, does not open the valve, rather the incoming pressure must overcome the spring on the schrader. This means that when you stop pumping and go to remove the fitting, the schrader is already closed and won't leak.

The downside, is that you need to generate the extra 70psi to crack the schrader open.

Gippeto wrote:The downside, is that you need to generate the extra 70psi to crack the schrader open.

... unless you "doctor" the stem spring