T-Shirt cannon pnuematic set ups

[Bryan Herbst]

Hey everyone,

Our team is hoping to build a t-shirt cannon this summer, but need some help.

First, to those that have built one before, or have an idea as to how to do it, could you list the pneumatic (or sprinkler) parts used, including valve/solenoid, tubing/hose, connectors, and pump? We've seen tutorials with how to do it with things like a bike pumb and manual release knob/switch, but not an electric one. If you could also link where you got it, that would be great.

Second, is there a (cheap) way to attach a digital PSI sensor to the pneumatics? We would like to adjust the PSI output from the OI, but we aren't sure if we can.

All help is appreciated.
Thanks!

[SSMike]

I'm sorry that I don't have any suggestions for pneumatics so I thought that I'd provide an alternative.

Well, I personally never built a t-shirt cannon with pneumatics but for an engineering class, I built an air cannon that could launch a nerf football through a goalpost. I felt that it was rather easier than pneumatics
imo. All I used was PVC piping, and a control valve (also PVC). We ended up launching the ball about 40 feet when the pressure was up to 30 psi, so it worked pretty well, and I'm sure would make a fine t-shirt launcher. If you decide to do this MAKE SURE YOU USE PRESSURE RATED PVC! I can not stress this point enough. If you want pictures or more detailed instuctions, just let me know.

Hope this helps.

[tdlrali]

valve/solenoidLook into sprinkler valves, I think those are used quite often for this kind of application. If I remember correctly NItro used sprinkler valves.

Second, is there a (cheap) way to attach a digital PSI sensor to the pneumatics? We would like to adjust the PSI output from the OI, but we aren't sure if we can.I'm sure you mean analog. If you find one, just shut the pump off at the desired pressure.

[RyanN]

I'm sorry that I don't have any suggestions for pneumatics so I thought that I'd provide an alternative.

Well, I personally never built a t-shirt cannon with pneumatics but for an engineering class, I built an air cannon that could launch a nerf football through a goalpost. I felt that it was rather easier than pneumatics
imo. All I used was PVC piping, and a control valve (also PVC). We ended up launching the ball about 40 feet when the pressure was up to 30 psi, so it worked pretty well, and I'm sure would make a fine t-shirt launcher. If you decide to do this MAKE SURE YOU USE PRESSURE RATED PVC! I can not stress this point enough. If you want pictures or more detailed instuctions, just let me know.

Hope this helps.

How about not just PVC at all!!! It has been stressed many times on different threads; PVC is not meant to hold air at any pressure above the atmosphere pressure.

We used an empty freon tank for our air tank, put two compressors to charge it, and we can safely handle up to 120PSI. We are using a 24V sprinkler valve from Lowes. These will not switch with 12V, as you probably figured out already, but what we did is hooked up a relay to a spike that switches on 3 9V batteries (27V). The 3 extra volts does not hurt the valve, especially for the duration that we use it. We used flexible hose to transfer the air... it kind of looks like a sewage line for an RV, but we also bought it from Lowes.

As for a sensor, I believe they supplied one in the kit before my time (2004 maybe?) that was manufactured by Texas Instruments.

Also, like I said before, there are other threads, not just on the safety issue of using PVC, but there are many, many threads on T-Shirt shooters. Just use the search feature.

Here is a link to ours: http://www.chiefdelphi.com/forums/showthread.php?t=39324&highlight=fusion+t-shirt+shooter

As you can see, the first version had a PVC tank, and after 2 years, we deemed it unsafe and I rebuilt it last summer in our 95 degree plus summer temperatures in our garage.

I also just noticed the pictures aren't working later on in the thread. I'm about to go look into it, so hopefully I can get it working.

[s_forbes]

We built one that runs off of just the kit compressor (fills tank in 10 seconds) and fires a shirt ludicrous distances, about 40 yards or so. Instead of a sprinkler valve, we used a pneumatically actuated gate valve (see it here (http://www.chiefdelphi.com/media/photos/29085)) that unleashes air stored in an abs reservoir into our pvc cannon. Overall it's a surprisingly simple and effective system, I'd suggest you look into it a little.

See the whole thread for our promobot here (http://www.chiefdelphi.com/forums/showthread.php?t=59027). Maybe squirrel or GUI or MattH can give you a better description of how it works if you have questions...

[RyanN]

To emphasize my point about no PVC... earlier this week, one of the kids at school was making a potato launcher and charged it to 45PSI when it exploded right in his face. Luckily he was not hurt by the explosion. It failed not in the PVC pipe, but the thick joints. This goes to show even though many think thicker is better, it is not always the case.

This was the tank that was used on our t-shirt shooter before we converted to a real tank.

So again, please DO NOT USE PVC. People can be seriously wounded, or even killed (as evident by the hole in the roof).

Also, I was not there when it happened, so I had no control over it. What appeared to happen was a crack rapidly developed in the joint, the glue failed, and then it shot the tank off like a rocket.

[kborer22]

what seems to be popular now are what looks like modded paintball guns. They have a similar set up, with an adapted barrel to hold a rolled up t-shirt (most made out or poly carb). If you can find a painball gun with a common thread size (aka not Tippman) then you should just be able to fabricate a barrel and give it a shot! (not sure how much pressure you would need vs. what a stock paintball gun could give you or how far you plan on launching it)

http://www.tshirtgun.com/home.htm

[Bryan Herbst]

Thanks for all the info an tips.

It's giving us a good start, and well be sure to follow up on some of the stuff posted here when we start to actually build it. We haven't actually started our off-season yet, we've just been gather ideas and plans.

[Nawaid Ladak]

we did one where it was PVC piping connected to 3 cylinders, you could strap it onto your arm, and it was connected to a battery pack and compressor in a backpack. very dangrous, but very cool. it could launch t-shirts one at a time, but we mainly used it for those little stress balls, ie the NI soccer balls that they had during te deminstration in the pits during championships.

also you might want to look into what diffrent sports teams use, i was at the magic game, and they had one built into a trash can, but it launched t-shirts rolled up into bals, with rubber bands.

[artdutra04]

Look into McMaster (http://www.mcmaster.com/) part number 8585K21 for barrel stock.

That's the pipe I used on my muti-barrel tee shirt launcher. Although it is on the expensive side, I had to guarantee that the tee shirt launcher would be safe to operate around large numbers of people outside, and at temperatures which had a good chance of being below freezing.

There was absolutely no PVC used anywhere on my launcher for safety reasons; everything that held pressure was rated for high pressure gas use and below freezing operation.

[Martijn]

I built a t-shirt cannon this fall, and we used it for some robotics promotional stuff. Took it to a basketball pep-rally, that sorta thing.. Although PVC might not be the safest thing, you're probably ok as long you make sure that not only the pipe itself, but also the fittings are all pressure rated. The only thing that isnt pressure rated in my setup was the sprinkler valve. We've managed to hook it up to 4 compressors, and load the reservoir all the way up to around 140PSI, and we can shoot t-shirts across our school's gymnasium (two basketball courts side by side).
We had also planned to hook it up to a promo robot (similar to 1726), but we ran out of time in the fall.. Maybe the team will hook the cannon up to a kit chassis with a mechanum drive or something this fall..

[artdutra04]

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.

[Akash Rastogi]

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.

And please make sure its UL certified no matter what you use.

(Underwriters Laboratory)

[SSMike]

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.


I agree. As I read my previous post, I realized that it could be seen that I was advocating a PVC air cannon. In no way am I doing so. I was simply stating how I built an air cannon. (Just a little disclaimer)

PVC is dangerous folks, and shouldn't be used for super-atmospheric pressures

[vivek16]

CRT 306 has had a safely functioning t-shirt cannon for some time now..using non-pressure rated pvc is perfectly fine for the minimal pressures that you're going to be working with..120 psi=not much..hit up any of our team members for more info..aim/ pyro20911..my cell # 814-462-4904

Actually, 120 psi is a lot. There is a reason FIRST has us use only 60 psi. If you do make a pvc gun, please, please make sure that you don't use pvc for the air storage or charging.

Wrapping the tube (barrel) in duct tape a lot and putting a bigger tube around it makes it a little safer.

be safe, Vivek

[Cody Carey]

Actually, 120 psi is a lot. There is a reason FIRST has us use only 60 psi. If you do make a pvc gun, please, please make sure that you don't use pvc for the air storage or charging.

Wrapping the tube (barrel) in duct tape a lot and putting a bigger tube around it makes it a little safer.

be safe, Vivek

When originally designing our T-shirt cannon, We looked at the pressure ratings listed in the Engineering toolbox.( http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html )

It clearly lists that the maximum allowable operating pressure for 3" schedule 40 (which is what we used) is 158 Psi, and the minimum bursting pressure is 840 psi. Considering that that is 38 psi above what the exhaust valve on the pump we were using is set to, combined with the fact that we had the tank encased in a plexiglass shield and we wouldn't be operating it in temperatures above 140F (thank God)... I'd say we were perfectly within the confines of what would be considered "safe".

As for wrapping the barrel and/or tank in Duct tape, and placing it in a larger section of pipe, that would not only make it a little safer, it would virtually eliminate any safety hazard at all. No shrapnel means no major injuries... and the chances of the larger pipe bursting (if it is sealed) are minimal as well, because the largetr pipe would be exposed to a much smaller pressure PSI than the little one was.

As for the reasoning behind FIRST having the teams limited to 60 PSI, I doubt it has to do with the bursting pressures of PVC,but can more likely be attributed to them being overly stringent with their safety regulations... but as there have been no major pneumatic related injuries that I know of thus far in the program, I'd be an idiot to argue with their reasoning.

I'd say that as long as you have the tank well guarded from any shock, and you don't abuse the thing, you're safe to use PVC in a 120 PSI system.

[AndyB]

I know a team built a tshirt cannon for use at one of our competitions this year that used PVC for air storage. They shot shirts on Thursday and part of Friday I believe before they were asked to stop because of danger.

If you aren't concerned about your own safety, please be concerned for everyone else's.

[RyanN]

When originally designing our T-shirt cannon, We looked at the pressure ratings listed in the Engineering toolbox.( http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html )

It clearly lists that the maximum allowable operating pressure for 3" schedule 40 (which is what we used) is 158 Psi, and the minimum bursting pressure is 840 psi. Considering that that is 38 psi above what the exhaust valve on the pump we were using is set to, combined with the fact that we had the tank encased in a plexiglass shield and we wouldn't be operating it in temperatures above 140F (thank God)... I'd say we were perfectly within the confines of what would be considered "safe".

As for wrapping the barrel and/or tank in Duct tape, and placing it in a larger section of pipe, that would not only make it a little safer, it would virtually eliminate any safety hazard at all. No shrapnel means no major injuries... and the chances of the larger pipe bursting (if it is sealed) are minimal as well, because the largetr pipe would be exposed to a much smaller pressure PSI than the little one was.

As for the reasoning behind FIRST having the teams limited to 60 PSI, I doubt it has to do with the bursting pressures of PVC,but can more likely be attributed to them being overly stringent with their safety regulations... but as there have been no major pneumatic related injuries that I know of thus far in the program, I'd be an idiot to argue with their reasoning.

I'd say that as long as you have the tank well guarded from any shock, and you don't abuse the thing, you're safe to use PVC in a 120 PSI system.

Even though these ratings are printed, for what type of application are they defining? Liquid or Gas?

Liquid does not compress very well, so the chance of PVC exploding with a liquid is very slim. However, gas does compress well, and therefore, the chance of the PVC exploding is much greater. You must also think about the size of the molecules and how they interact with the structural integrity of the PVC pipe. Liquid molecules in general are much larger than gas molecules, so liquid can be contained much easier.

Here is an example of what I'm getting to:
You have 2 balloons, fill one with water and one with gas. Wait a week and look at the size of both balloons. I bet the one with liquid is much larger than the one with gas. Also try popping both balloons. The one with air will be much more violent. This same concept applies to PVC pipe.

We've had our own accident with PVC exploding in a kids face, and he could have been killed very easily. He was well in the 120PSI zone (around 40PSI) when a coupling split in two pieces and made the whole tank shoot off like a rocket into the ceiling.

Also, PVC tanks do weaken over time from expanding and contracting. Water lines do the same, but most water lines remain compressed all the time, so the process is much slower. With an air cannon, it goes from 0PSI to xPSI every time it is shot.

There have been many horror stories of PVC exploding and people saying not to do it:
http://www.osha.gov/dts/hib/hib_data/hib19880520.html
http://www.youtube.com/watch?v=AQo81nqx-W8
http://www.cnczone.com/forums/archive/index.php/t-35978.html

[Bryan Herbst]

Okay, we finally got around to putting stuff together, and we are looking for tips on how to improve the cannon.

It actually has pretty decent range (shoots t-shirts about 30-40 feet), but it takes about a minute to fully pump up the tank. Now, this is pumping it to 80 PSI, but right now we are working at someone's house, not the school, so we should be able to lower the PSI and still be able to get shirts into the stands.

Currently, the barrel and tank are both made of 3 inch diameter PVC (please keep reading) and are both about 30 inches long. We are pumping the tank with two of the KOP air compressors. It takes about 1 minute and 40 seconds to pump the tank full with one compressor.

Now, as for the PVC tank- Yes, we are aware it is dangerous. However, we are limited on funds (currently have NO sponsors), and don't have many other options right now. We will be getting a different tank ASAP, but this is what we have right now. We have taken plenty of safety precautions (we stand around the corner from the tank, so if the tank explodes, it will explode into a wall and the person's lawn).


Now, if someone could suggest how to get a better pump, a better tank, or another way to do this more efficiently/effectively, we would be much obliged.

EDIT- Just remembered, and thought I would mention- We are currently using a 24v sprinkler valve hooked up to a standard FIRST control system (i.e. a 12v circuit). Would this make the solenoid open slower, and thus give us less bang per shot, or would it really not affect it at all?

[Andrew Schuetze]

take a look at our development of a similar system which has been documented here on C.D. The sprinkler valve you mention has also been discussed on C.D. and even a very nice animated graphic shows how it works. It is a relatively slow opening with a membrane that does flap during exhaust. Does your cannon honk when it shoots? Ours did.

We currently use 1 inch black pipe with npt thread for air storage as it is rated for pressurized air and is available at hardware stores. Stainless pipe is also available. One could even use a 5 gallon Craftsman air tank with only cost $20. On our system, the valve is immediately after the black pipe so that the pvc tubing and barrel do not maintain pressure except during the shot. We got better results when going to the manual ball valve but the best results are with the valve rated for this purpose. The local Parker dealer donated the valve to our team as it lists for $100.

Craftsman air tank (http://www.chiefdelphi.com/media/photos/25537)


Ball Valve (http://www.chiefdelphi.com/media/photos/25728)


Parker Valve (http://www.chiefdelphi.com/media/photos/28675)

[R.C.]

We used ABS and could someone post material that is rated for a 1,000 psi. Ours works successfully, but we want to rebuild it. Also use a sprinkler valve, it works really well.

[RyanN]

We use 2 KOP compressors to charge our tank. It still takes a long time to charge from 0PSI to shooting pressure, but we can get 3 shots out of the tank before having to wait again.

We are using an old freon tank used to charge air conditioners that was empty. It's a bit large for our use, although I can't think of any other tanks that would work better.

For the sprinkler valve, we connected 3 9V batteries together in series to a relay (not a spike) and connected the relay to a spike. This gives the sprinkler valve 27V of power, which shouldn't hurt it at all (and hasn't hurt it over the past 4 years). We put a software limit on the amount of time the shooter can shoot which saves on air and charging time.

The example above (http://www.chiefdelphi.com/media/photos/25537) me is pretty much the system we use.

[Mr. Freeman]

Liquid molecules in general are much larger than gas molecules

I don't think the size of molecules changes when changing states from liquid to gas.

[gorrilla]

pressure rated pvc pipe is perfectly fine to us as long as you dont exceed the rating

abs plastic is not pressure rated but when it fractures its like safety glass on a car YOU SHOULD NEVER USE ABS PIPE



steel pipe is the best but most people dont have lots of money for steel pipe



bottom line you can use pressure rated pipe as long as you are smart and dont exceed the rating

[RyanN]

I don't think the size of molecules changes when changing states from liquid to gas.

Is liquid not thicker than air? Try to move your arm through water, then do it through air. You will notice a big difference. Gas is much more free and energetic than liquid. That's my point. The actual size of the molecules don't change from changing states, but the different molecules in the gas form and in the liquid form are much different.

[NickE]

the different molecules in the gas form and in the liquid form are much different.
Actually, I believe that the molecules are the same. The difference is the spacing between the molecules.

[RyanN]

Actually, I believe that the molecules are the same. The difference is the spacing between the molecules.

I guess that's what I'm trying to explain. Gas likes to escape faster than liquid. Liquid does not compress well while gas does.

Basically the point is that PVC should never be used to store air unless you are expecting an explosion at any time. I would never recommend using PVC. I saw what it can do, and don't want it to explode in my face. If it's a very far from anyone and inside a steel container I would then feel safe using it. Otherwise I would never use it. The kid had a failure at 40PSI while he was still charging it up to 60PSI. It was not thin pipe at all. It was very thick. It failed at a joint. It cracked the whole piece, then released the top section like a canon straight up into the ceiling. This happened at 40PSI. I know the water pressure in my home is right at 60PSI. PVC is not designed to hold air. It's not safe. It fails unexpectedly unless you drop it, and if you do that, you better run like a mad man, because it's very likely to go off. A PVC pipe with 60PSI of air, or 100PSI, or whatever is a bomb. Note that I did not use like a bomb. It is a bomb. A grenade. Unsure of when it will go off.


Hopefully I'm getting my point across. Don't use PVC for the tank. The way they're describing they're using it sounds pretty safe, but make sure no one, and I mean no one, is around it at all. There shouldn't be anyone within 100 yards of your tank when it's pressurized. Be behind the wall and don't go out unless it's not pressurized anymore.

[artdutra04]

pressure rated pvc pipe is perfectly fine to us as long as you dont exceed the rating"Pressure Rated PVC" is only rated for liquids under pressure. That means it is NOT rated for gases under pressure.

When liquids are under pressure, and if a crack in the PVC appears, the worst that may happen is a crack appears that releases the water safely and slowly. When gas is under pressure, and is a crack in PVC appears, the result is catastrophic and spontaneous explosion of shrapnel in all directions.

If you want a demonstration of this, take a balloon and fill it with water. Then take another balloon and inflate it with air. Take a knife or a thumb tack and pop the water balloon. Then pop the air-filled balloon.

The water balloon will most likely just kind of split open and spill water everywhere. The air balloon will violently pop and pieces of the latex balloon will fly everywhere. The same thing happens with PVC.

Just because it may say "Rated to 150 PSI" or something on PVC does not mean it works for everything under pressure.

[gorrilla]

take a soda bottle down about 100 feet under water and fill it with air and let it float the the surface



by the by water is just as dangerous as air under pressure and water under pressure explodes things too


they test scuba tanks by filling them with water to 3000psi

[artdutra04]

take a soda bottle down about 100 feet under water and fill it with air and let it float the the surfaceThis hypothesis does not make PVC safe to use with gases under pressure.

If you do that, you will have to fill the water bottle to a high enough pressure to match (or exceed) the water around it, otherwise it will be crushed by the water pressure. If you make the air pressure in the bottle match the ambient water pressure around it, then at 100 feet down everything will be in equilibrium and nothing spectacular will happen.

Despite being at the same pressure, the mass of air inside the bottle is less than equivalent mass of water at the same volume, so the bottle will float upward. As it hits the surface, the relative pressure difference between the bottle and the water around it will begin to skyrocket. At it hits the surface, the pressure of the water bottle will be very high compared to the water/air around it, and then has a high chance of violently exploding. The resulting possible explosion would be very much like that if you filled a water bottle 1/3 with water, put in some dry ice, screw on the lid, then run like there's no tomorrow - e.g. a very violent and VERY LOUD explosive decompression (http://www.youtube.com/watch?v=rkOtLgAxdRs).

The same thing can happen to the dissolved gases in the blood stream of divers who surface too fast, resulting in the bends (http://en.wikipedia.org/wiki/Decompression_sickness).


by the by water is just as dangerous as air under pressure and water under pressure explodes things too


they test scuba tanks by filling them with water to 3000psiI never said water [or more generally, liquids] under pressure are not dangerous, as in fact it can cut through objects six or more inches thick in the form of a waterjet.

How materials react to these differences between pressurized liquids and gas is what I am concerned about. PVC reacts much more violently during a fracture with pressurized gases rather than pressurized liquids, which is why PVC is banned by OSHA for any pressurized gas applications.

Avoiding PVC for pressurized gases is like never pointing a gun towards anyone at any time, or always using your seatbelt in a car. Sure, you can always claim a few times where one has ignored these concerns and nothing bad happened. But accidents are just that - accidents - and by not following safety guidelines you seriously increase the risk of serious bodily harm to both yourself and anyone around you.

[Spartan151]

Okay. I've been following this for a couple days. I figured that a t-shirt cannon would be a nice idea for our team, since at least half of us are graduating this year. This leads me to ask some questions before attempting a build.

Question 1: In regards to the air tanks, what kind of material could I use for pressurized air storage?

Question 2: Is it possible to use a high-pressure rated tank or such for a "rifle-style" t-shirt cannon without the need of having to carry around a storage tank?

Question 3: On the barrel part, since I DON't plan to use PVC for storage, can I use a strong duct tape-wrapped PVC pipe for just a place to load the t-shirts?

Question 4: What is the best way to design one that is safe? (We don't have a huge budget, so buying one is a bit of a problem.)

Question 5: What kind of sprinkler valve/solenoid should I use and where can I get one from?

[Mr. Freeman]

I don't know what thread it was in, but someone on this forum posted awhile back about doing some tests and finding that duct tape doesn't prevent shrapnel.

[Spartan151]

Well, I've been tinkering, looking at Fusion's setups, and I've come up with my own design. Now, I wouldn't go replicating the idea I'm going to post if I were you, not until I give some feedback on how it did.

Here's the setup. I took a two foot long, 3-inch PVC pipe, added a 3in. coupler, put a 3-to-1 1/2 reducer, then a 1 1/2 to 1 reducer, to fit the Rainbird Sprinkler Valve. The Sprinkler Valve electrical system I'll explain later.
keep in mind that the PVC IS NOT USED FOR AIR STORAGE AT ANY POINT ON THE GUN! the only time it comes in contact with air is when the gun fires, and even then it's triple-reinforced in the joint sections, and I made sure to take an extra careful amount of time while assembling it.

Next, I plan to get hold of some tubing that can be pressurized to at least 110 PSI. This will enable me to have a variable adjustment rate without a risk of bursting. The hose will run to a connector, which will be tapped to an old Freon tank, much like Fusion's design. The tank will have a fill nipple, a pressure gauge for the tank, a hand valve for on/off, a regulator, another gauge for the regulator, and then the place to mount the hose.

As for electrical, I bought one of those little black boxes from Radio Shack, took a toggle switch (One of those that has a protective cover over the switch to prevent accidental turn ons). this switch acts as a safety. When this switch is on, a red light on the panel part is on, and a bright blue light powers up on the side. two of the 9v batteries are inside the box, and one 9v is outside of it attached by a "cradle". This allows me to pull the battery off for mainenance purposes, or simple power down. Next, the wires run to a "trigger" setup, and then to the solenoid wires itself, for activation of the valve.

Again, I wouldn't recommend attempting this until I have posted back with lots of feedback and testing results. If you do, okay, but I hope you take the time to think things through. I don't want to hear of someone getting hurt because of my design. Better me than you. Good luck, cannoneers.

[Daniel_LaFleur]

Okay. I've been following this for a couple days. I figured that a t-shirt cannon would be a nice idea for our team, since at least half of us are graduating this year. This leads me to ask some questions before attempting a build.

Question 1: In regards to the air tanks, what kind of material could I use for pressurized air storage?

Question 2: Is it possible to use a high-pressure rated tank or such for a "rifle-style" t-shirt cannon without the need of having to carry around a storage tank?

Question 3: On the barrel part, since I DON't plan to use PVC for storage, can I use a strong duct tape-wrapped PVC pipe for just a place to load the t-shirts?

Question 4: What is the best way to design one that is safe? (We don't have a huge budget, so buying one is a bit of a problem.)

Question 5: What kind of sprinkler valve/solenoid should I use and where can I get one from?

1> Use steel or aluminum tanks rated for 3x higher than your working pressure. Other materials may be used but stay away from PVC as it fails explosively.

2> You can use a smaller High pressure tank. The compressed air will weigh the same and the tank will weigh less. Again I suggest a 3x safety margin from storage pressure. Also, you will need to regulate down from this high pressure and that may cause restriction in the air flow.

3> Duct tape does virtually nothing if the PVC fails. DO NOT USE PVC. I cannot stress more that PVC does not like the shock loads that an air cannon provides and when it fails (not if) it will fail explosively.

4> Understand the forces used and the gas laws that apply (especially that gas exerts the same force in all directions ... not just out the barrel). Design with safety in mind and always err on the side of caution.

5> You need a valve with a large orifice that unseats quickly. Many have chosen sprinkler valves for this type of use ... but I'd look closer at vane valves myself.

Good luck and play safe.

[Daniel_LaFleur]

Here's the setup. I took a two foot long, 3-inch PVC pipe, added a 3in. coupler, put a 3-to-1 1/2 reducer, then a 1 1/2 to 1 reducer, to fit the Rainbird Sprinkler Valve. The Sprinkler Valve electrical system I'll explain later.
keep in mind that the PVC IS NOT USED FOR AIR STORAGE AT ANY POINT ON THE GUN! the only time it comes in contact with air is when the gun fires, and even then it's triple-reinforced in the joint sections, and I made sure to take an extra careful amount of time while assembling it.


The PVC barrel will see a shock load that is equal to the pressure in the tanks. This shock load will be applied in under 1ms. It is this shock load that will sunder PVC as the PVC cannot expand fast enough when the shock load is applied (cannon is fired).

Again, I highly recommend not using PVC for ANY pneumatic device ... especially ones that will sustain shock loads such as air cannons.

[Spartan151]

The PVC barrel will see a shock load that is equal to the pressure in the tanks. This shock load will be applied in under 1ms. It is this shock load that will sunder PVC as the PVC cannot expand fast enough when the shock load is applied (cannon is fired).

Again, I highly recommend not using PVC for ANY pneumatic device ... especially ones that will sustain shock loads such as air cannons.

Okay. I wanted to clarify that, and it's a little easier to understand when you put in in terms of a shock load. I've got some other tubing for backup in case it wasn't going to work, with all the fittings ready. Thanks for clarifying that.

grateful, Sean :)

[rokenboker]

team 1236 here and i have built one and it works great!


here goto this page on the site


http://www.chiefdelphi.com/forums/showthread.php?t=69073

[Beener]

This is what we came up with.

http://www.chiefdelphi.com/media/img/20b/20b5efbb85cf285e5b4772c55cc30525_l.jpg

[Adama]

If in fact PVC is incredibly dangerous I have a few questions.

The discussion here has been only about air powered guns. Is there any greater or less danger in combustion guns? ( I'm aware that this would be disallowed on school grounds, its just a question of principle) I imagine that the lack of high pressure storage gives some what more safety though there is more of a spiking pressure affect that could counter act this.

Also on the topic of air cannons what are peoples opinions on the below link?

http://www.spudfiles.com/

I realize that it is the internet and not a well researched set of standards but one must question the danger involved if there has been a large community of people using these devices for years now. They have there share of accidents (as does any hobby such as dirt biking or snow boarding, etc) but it would seem that they only happen to people who didn't follow the well known safety practices and construction techniques established over time by the general spudding community. I guess that that if PVC were as dangerous as we are discussing then most of these people would have killed themselves by now.

[gorrilla]

If in fact PVC is incredibly dangerous I have a few questions.

The discussion here has been only about air powered guns. Is there any greater or less danger in combustion guns? ( I'm aware that this would be disallowed on school grounds, its just a question of principle) I imagine that the lack of high pressure storage gives some what more safety though there is more of a spiking pressure affect that could counter act this.

Also on the topic of air cannons what are peoples opinions on the below link?

http://www.spudfiles.com/

I realize that it is the internet and not a well researched set of standards but one must question the danger involved if there has been a large community of people using these devices for years now. They have there share of accidents (as does any hobby such as dirt biking or snow boarding, etc) but it would seem that they only happen to people who didn't follow the well known safety practices and construction techniques established over time by the general spudding community. I guess that that if PVC were as dangerous as we are discussing then most of these people would have killed themselves by now.


I would definately say thats a combustion gun would be even more dangerous:ahh:

PVC SHOULD NOT to be used EVER for anything being pressurised except for WATER and this should be the end of it(unfortunately it most likely wont:( )

and on the topic of alot of people using PVC, I belive there just asking for it, but its thier decision:o
Ill' give you that PVC dosent ALWAYS explode(which is why alot of people use it) but IF it does,someone COULD be seriously hurt, I dont know about you guys, but I would rather not risk having someone else injured because of me:rolleyes:

I also belive this has been said before MANY MANY times by far more experience people than me

[skimoose]

If in fact PVC is incredibly dangerous I have a few questions.

The discussion here has been only about air powered guns. Is there any greater or less danger in combustion guns? ( I'm aware that this would be disallowed on school grounds, its just a question of principle) I imagine that the lack of high pressure storage gives some what more safety though there is more of a spiking pressure affect that could counter act this.

Also on the topic of air cannons what are peoples opinions on the below link?

http://www.spudfiles.com/

I realize that it is the internet and not a well researched set of standards but one must question the danger involved if there has been a large community of people using these devices for years now. They have there share of accidents (as does any hobby such as dirt biking or snow boarding, etc) but it would seem that they only happen to people who didn't follow the well known safety practices and construction techniques established over time by the general spudding community. I guess that that if PVC were as dangerous as we are discussing then most of these people would have killed themselves by now.

This is the most reoccurring issue with air launchers and combustion "guns". PVC is extremely dangerous!!
The PSI rating printed on the pipe is for liquids NOT compressed gases of any sort. The biggest problem with PVC is that its failure, when it occurs, is catastrophic. PVC shatters into numerous sharp shards that can be propelled at dangerous levels. PVC generally will not exhibit signs of fatigue until it explodes. People have also argued that PSI is PSI, so why isn't PVC safe with compressed gas? By the very natural of solids, liquids and gases, gases will release stored energy much faster than a liquid will, even liquids can still dangerous.

As far as your logic of a lot of people using these devices and none being hurt. That is a falsehood perpetuated by the internet. I have seen posting of failures but they are few and far between because most people don't want to post their failures, only their successes, and they certainly wouldn't post if someone was injured (don't you think the lawyers would love to get their hands on that incriminating evidence). Also, in most cases these people use these devices a few times before tiring of them, or getting caught (combustion guns). They've rolled the dice a few times and lucked out. PVC failure is generally from fatigue which means each time you load and unload the pipe you stress it and each time your chances of a failure increase. Load that pipe enough times and it will certainly fail.

I personally know at least four incidents of PVC failures. Luckily, no one was seriously hurt ONLY BECAUSE OF PURE LUCK! In one case, an individual had a charges air launcher under his coat. Luckily it failed away from his body, but it completely shredded a heavy winter jacket being worn. If you saw the jacket, you'd think the person wearing it was DEAD! Pure Luck plain and simple.

Our Dewbot T-shirt air launcher is built with an all metal storage accumulator, piping, and valve system in which every component used was rated at over 150 PSI. Where we used flexible hose (after the solenoid valve) it was rated at over 180 PSI and is reinforced so that a rupture would only cause a tear in the material. The launcher tubes are made out of polycarbonate pipe which is rated at 9000 PSI and was $11/foot. That should give you some idea of how seriously we took safety when using plastic pipe, even polycarbonate.

Don't be misled by what you don't find on the internet.

[Tom Line]

pressure rated pvc pipe is perfectly fine to us as long as you dont exceed the rating

abs plastic is not pressure rated but when it fractures its like safety glass on a car YOU SHOULD NEVER USE ABS PIPE



steel pipe is the best but most people dont have lots of money for steel pipe



bottom line you can use pressure rated pipe as long as you are smart and dont exceed the rating

It terrifies me when people make posts like this without understanding they may very well be placing somebody in harms way.

I wonder what type of professional engineering or material engineering degree this person has. I wonder what license and what expertise are this person bases his statement on.

OSHA and the manufacturers say NO.

http://www.osha.gov/dts/hib/hib_data/hib19880520.html

[Mr. Freeman]

I wonder what type of professional engineering or material engineering degree this person has.

No offense, but I could ask you the very same question. I don't think you've explained what degree you hold.

[Daniel_LaFleur]

If in fact PVC is incredibly dangerous I have a few questions.

The discussion here has been only about air powered guns. Is there any greater or less danger in combustion guns? ( I'm aware that this would be disallowed on school grounds, its just a question of principle) I imagine that the lack of high pressure storage gives some what more safety though there is more of a spiking pressure affect that could counter act this.


Combustion guns use expanding gasses to propel the object, and therefore are still inherently dangerous to use PVC with. In addition, the lack of specific gas pressure control and the addition of heat will most likely cause the PVC to fatigue faster.


Also on the topic of air cannons what are peoples opinions on the below link?

http://www.spudfiles.com/

I realize that it is the internet and not a well researched set of standards but one must question the danger involved if there has been a large community of people using these devices for years now. They have there share of accidents (as does any hobby such as dirt biking or snow boarding, etc) but it would seem that they only happen to people who didn't follow the well known safety practices and construction techniques established over time by the general spudding community. I guess that that if PVC were as dangerous as we are discussing then most of these people would have killed themselves by now.

People will always do stupid things and then brag about their "success". Don't be the one that "fails".

Please take it from someone who has had a 1 liter volume, pressurized to 100 PSI, blow up on him at close range (ME). It is dangerous, very dangerous.

[Adama]

This is the most reoccurring issue with air launchers and combustion "guns". PVC is extremely dangerous!!
The PSI rating printed on the pipe is for liquids NOT compressed gases of any sort. The biggest problem with PVC is that its failure, when it occurs, is catastrophic. PVC shatters into numerous sharp shards that can be propelled at dangerous levels. PVC generally will not exhibit signs of fatigue until it explodes. People have also argued that PSI is PSI, so why isn't PVC safe with compressed gas? By the very natural of solids, liquids and gases, gases will release stored energy much faster than a liquid will, even liquids can still dangerous.

As far as your logic of a lot of people using these devices and none being hurt. That is a falsehood perpetuated by the internet. I have seen posting of failures but they are few and far between because most people don't want to post their failures, only their successes, and they certainly wouldn't post if someone was injured (don't you think the lawyers would love to get their hands on that incriminating evidence). Also, in most cases these people use these devices a few times before tiring of them, or getting caught (combustion guns). They've rolled the dice a few times and lucked out. PVC failure is generally from fatigue which means each time you load and unload the pipe you stress it and each time your chances of a failure increase. Load that pipe enough times and it will certainly fail.

I personally know at least four incidents of PVC failures. Luckily, no one was seriously hurt ONLY BECAUSE OF PURE LUCK! In one case, an individual had a charges air launcher under his coat. Luckily it failed away from his body, but it completely shredded a heavy winter jacket being worn. If you saw the jacket, you'd think the person wearing it was DEAD! Pure Luck plain and simple.

Our Dewbot T-shirt air launcher is built with an all metal storage accumulator, piping, and valve system in which every component used was rated at over 150 PSI. Where we used flexible hose (after the solenoid valve) it was rated at over 180 PSI and is reinforced so that a rupture would only cause a tear in the material. The launcher tubes are made out of polycarbonate pipe which is rated at 9000 PSI and was $11/foot. That should give you some idea of how seriously we took safety when using plastic pipe, even polycarbonate.

Don't be misled by what you don't find on the internet.

First of all I have read the entire thread and am well aware of the facts you stated in red text several times before. I wasn't speaking so much as in defense as more of an awarness of a very large community. It was an attempt to bring to light more than what had been discussed already. The internet is and can be very misleading but none the less it is present and full of more empirical data (probably positively biased) and trial and error on the subject than can be completely ignored.

On a side note I have built and operated a combustion gun for several years now. (if you can't make one you probably shouldn't have one::ouch:: ) Its stored inside away from temperature extremes, I do not fire it in extreme cold, I use weak fuel such as hairspray and I always treat it as an actual fire arm. That is why I was probing into combustion guns.

[EricH]

No offense, but I could ask you the very same question. I don't think you've explained what degree you hold.Neither have you, programmer. What materials courses have YOU had?

As for the original question, I'm pretty sure high school students don't have degrees in engineering. They may have experience or expertise in doing stupid things, but I'm not sure I'd trust that.

On the other hand, a mentor whose rookie year was 1999, even if he was a freshman in high school at the time, would most likely have an engineering degree by now and a year or so "in the field", minimum. If said mentor is in any form of mechanical, materials, civil, or possibly even industrial or electrical engineering, I would be willing to bet that he's had at least one materials course, and possibly more. There's a chance even if he's more of a computer type of engineer. If said mentor was older than a freshman in his rookie year, it's still more likely that he's had both the education and the experience.

If I had to choose between a high school student with no training other than experience in doing things that aren't necessarily safe and a mentor who's most likely had the training and the experience of doing things the safe way, but not guaranteed, I'd take the mentor every time.

[Mr. Freeman]

My point wasn't to start an argument about who has taken what classes here. It was more to emphasize that asking people rhetorical questions in an insulting manner isn't the best way to solve this PVC vs. no-PVC argument.

Anyway, in another thread about air cannons someone mentioned that what actually causes PVC to fail when using it with compressed gasses is the shock loading. I haven't seen that mentioned here, it's probably important.

[Tom Line]

My original post had a good dose of sarcasm - I get that way when I see someone putting others in harms way with no good proof.

Here are a few more resources:
http://www.articlesbase.com/technology-articles/the-importance-of-pvc-pipe-and-fittings-to-the-world-495648.html

http://www.lni.wa.gov/Safety/Basics/HazAlerts/902.asp

http://erd.dli.mt.gov/safetyhealth/brochures/compressedgassafety.pdf

Here are some wonderfully instructive videos on what happens:
http://www.crazybuilders.com/forum/showthread.php?p=29

http://www.astm.org/Standards/D1785.htm

http://www.ppfahome.org/pvc/index.html

If, by now, this discussion is not at an end, I the person here said it best:
http://www.garageofevil.com/faq/showdoc.php?id=35

If that does not answer the question as to why you should not use it for this purpose, you should add yourself as a corpse prop to your haunt now.

[Matt Howard]

Now that this thread has been completely hijacked by an Ego contest....


When I built my air cannon in high school, I had the help of my father who has worked in Water Treatment for about 30 years, so thankfully I was blessed with knowledge from above about pressure ratings.

I used 4 inch Galvanized Steel, and typically ran it at 135 PSI.

I was able to launch aluminum baseball bats about 250 yards with about a gallon of water in the barrel.

Enjoy some very dated pictures:

http://i229.photobucket.com/albums/ee71/phschallenger/44378348acanon.jpg

http://i229.photobucket.com/albums/ee71/phschallenger/44482832matcannon.jpg

http://i229.photobucket.com/albums/ee71/phschallenger/44481881124566.jpg

http://i229.photobucket.com/albums/ee71/phschallenger/444819701234.jpg

[billbo911]

Now that this thread has been completely hijacked by an Ego contest....


When I built my air cannon in high school, I had the help of my father who has worked in Water Treatment for about 30 years, so thankfully I was blessed with knowledge from above about pressure ratings.

I used 4 inch Galvanized Steel, and typically ran it at 135 PSI.

I was able to launch aluminum baseball bats about 250 yards with about a gallon of water in the barrel.

Enjoy some very dated pictures:




The wisdom to take from this post is that the pressure tank was built out of steel, not PVC. Secondly, from the looks of what was built, I would say it really didn't cost that much to build either, and could be easily reproduced.

Now my next question.
From the looks of the pictures, that shattered bat happened before it hit the ground. Take a close look a the bottom of the picture showing the canon firing. Look at the shadow, it looks like the bat has broken already. Is this correct?


BTW, I love the use of water to seal around the bat and act as a sort of Sabot! Besides, it looks AWESOME!

[Matt Howard]

It was actually somewhat expensive to build. The 4 inch galvanized steel pipe with all the fittings was about $160 at a pipe house. Also, large pipe wrenches were required to assemble it.

The result however, is something I wont have to worry about overcharging, as well as insanely durable.

I'm going to have to say, yes the bat was broken.

We Launched it across a field into the back of a concrete wall just to see what would happen. (This is what happens when freshmen and sophomores are left unsupervised with an air cannon) Turned out the bat launched far more effectively after the end had broken off, as the inside of the bat was hollow, and allowed for a sort of "rocket" effect.

Oranges are great projectiles, as they explode on impact like a paintball. Never actually tried a potato, but considering that this is more of a pneumatic "anything that will fit into the 11 foot barrel cannon"..... :D

[gorrilla]

It was actually somewhat expensive to build. The 4 inch galvanized steel pipe with all the fittings was about $160 at a pipe house. Also, large pipe wrenches were required to assemble it.

The result however, is something I wont have to worry about overcharging, as well as insanely durable.

I'm going to have to say, yes the bat was broken.

We Launched it across a field into the back of a concrete wall just to see what would happen. Turned out the bat launched far more effectively after the end had broken off, as the inside of the bat was hollow, and allowed for a sort of "rocket" effect. :)


what's the wall thicknesss?

[Matt Howard]

About a foot of reinforced concrete.

[billbo911]

what's the wall thicknesss?

About a foot of reinforced concrete.

I think he may have been asking about the pipe.

[gorrilla]

I think he may have been asking about the pipe.

In fact I was;)

and I never thought that bats could "pop" like that:eek:

[jspatz1]

Our Lunacy robot this year used a catapult to launch moon rocks up to 35ft, so it is ready to go as a t-shirt launcher with no changes! Just need to bundle up the shirts into an approximate ball.

[Matt Howard]

In fact I was;)

and I never thought that bats could "pop" like that:eek:

Lol, that somehow flew completely over my head.

I don't know the wall thickness. It's class 150 Galvanized Steel.

[dpeterson3]

Our team built one about three years ago for school. With the exception of 2 parts, the entire thing is PVC. The tank has been preasure tested up to 60 PSI with no problems. We only need about 20 psi usually, though. Our first attempt, the tank blew off. That was my fault. I didn't clean the PVC well and didn't use primer. Those are very necessary. Now it works great. If the towels (we use rally towels because they are a lot cheaper than shirts) are rubber-banded before they are loaded into the barrel, the go much farther. Our bleachers are built into a hill at about a 60 degree angle below the horziontal. From the bottom,. we can shoot over the booth with only 30 pounds of air. If you want, I can send you preformance statistics, videos, adn a few pictures on what not to do.

Good luck

[Cody Carey]

This is a double post, but I think you guys might like to read it over here, as well.
Hey all... I just wan to clear some stuff up about PVC, and there really isn't a better way to do that then to borrow Some words from a physics prof on a forum I frequent.

I can understand why Fred and others here feel a strong twinge of concern when someone in school suggests using PVC for an air tank. We've all seen explosions from pressurized tanks and pipe, and students don't typically have the experience to know how to design and test pressurized systems. Sure, we've all seen potato guns, but we don't know what it is you're really planning to build, it sounds a bit more sophisticated. And besides, potato guns have been known to explode.

The piping codes in the US apply to these systems. This would fall under ASME B31.3, Appendix A. Note appendix A refers you to the main body of the piping code for most calculations. I'll be using this as a guide to make suggestions.

Regarding materials, PVC pipe falls under ASTM D 1785 or D 2241. The fittings fall under a variety of ASTM standards including ASTM D 2464, D 2467 and D 2468. There are others. If you decide to use PVC, one thing that would help ensure safety would be to verify one of these numbers is printed directly on all the pipe and fittings you use. If they don't have these ASTM numbers printed on them, they probably don't meet the minimum standards and shouldn't be used.

Cements used for PVC pipe should meet ASTM D 2564. Verify the stuff you purchase meets this code. Follow the directions on the can.

None of the pipe should be threaded except for purchased fittings. Everything should be glued using the appropriate cement. If you cut any threads, you're doing something dangerous.

At 70 psi, you have a roughly 3 to 1 safety factor on top of the standard safety factors. The "stress allowable" for PVC at 100 F is 1.6 ksi which says the pipe is good for roughly 210 psi operating pressure. If temperature exceeds this, the pressure rating drops off very quickly, I'd not recommend it above this temperature. The code also prohibits its use below 0 F. If the plastic gets cold, which it could because of the expanding gasses doing work on whatever, wait till it is warm again before pressurizing. Cold plastic is more likely to break.

Consider what external stresses you are imposing such as bending of the pipe between supports. The pipe should be reasonably well supported over long sections.

Once you've manufactured the piping, do a pressure test on it using water. Fill with water, make sure there is no air in the system, and then pressurize to at least 200 psi, preferably 300 psi. Hold this pressure for 5 minutes, then release the pressure and verify there are no leaks or distortion of any part. If it holds this pressure, I'd feel a lot better about using it.

I'd also suggest repeating this pressure test every 100 cycles or whenever you suspect damage or leave it sitting for extended periods of time. Cyclic pressure and other uncontrolled factors could damage the piping, regular testing will help prevent catastrophic explosions.

Verify all valves you use are rated for the given pressure.

You really should have a relief device, set at about 100 psi, immediately downstream of your regulator, just in case the regulator fails.

For a pressure source, do not use any source of pressure above 150 psi. High pressure cylinders are extremely dangerous.

Off hand, I can't think of anything else to warn you about. Maybe the others here could suggest specific considerations.

In short, as long as everything is set up correctly, and safety checked multiple times, tehre is very little that can go wrong, especially while operating at 100psi and under... a 2 to 1 safety factor on top of standard is really good.

I'm not saying this is a good Idea, but people in my local offroading club have been using PVC as air tanks for portable systems for years. They mount these on bottoms of bumpers, roll cages, and other places where they are almost sure to get hit, and HARD. When I went to my first meeting and saw that, I remembered threads like this from when I frequented CD and asked if they'd ever had any blowouts or problems associated with this, and I was surprised to find that there had only been one... And it had happened when the guy forgot to put PVC cement on an end cap.

Hows that for working in the real world?

As a side note, the reason he says to test the system with liquid is because at pressure, the main difference between water and air is that air will explosively expand when a crack or weak spot is formed, and water won't. This means that if you have a leak and fill it with water, you won't have any sort of explosion, and if it holds up for five minutes at 200 psi, you know you won't have any problems below 100.


Then again, It's pretty easy just to weld up a steel tank.

[Matt Howard]

Guys, its not difficult or that much more expensive to just use steel.

I would have thought by this point of the thread everyone's opinions would have drifted that way, and I'm really surprised that it hasn't.

Steel is far stronger, safer, and tolerant than PVC is.

Long story short, if you want an air cannon, you want steel.

[Terminator]

Hey everyone,

Our team is hoping to build a t-shirt cannon this summer, but need some help.

First, to those that have built one before, or have an idea as to how to do it, could you list the pneumatic (or sprinkler) parts used, including valve/solenoid, tubing/hose, connectors, and pump? We've seen tutorials with how to do it with things like a bike pumb and manual release knob/switch, but not an electric one. If you could also link where you got it, that would be great.

Second, is there a (cheap) way to attach a digital PSI sensor to the pneumatics? We would like to adjust the PSI output from the OI, but we aren't sure if we can.

All help is appreciated.
Thanks!

Looks great. Any way that I can get the plans and list of parts from you? Any other team that has built them, please let me know.
Have any of you built a handheld launcher? Please e-mail me any information to cpbio@aol.com

[McGyver]

the Physics class at my school made a t-shirt cannon and they used a sprinkler valve to fire it, but they also used a SCUBA tank and regulator before it. as for the pressure gauge, there are digital gauges available for under $5 that just use a sensor with a variable resistance. I believe that there is a LEGO 'hack' website that has instructions on how to pirate the gauge and use it as a sensor.

[gallo26]

Wow awesome! Glad to see other teams making T Shirt cannons!

We're building our 3rd generation cannons right now into our robot. Sprinkler valves are the best to release the pressure because they can be controlled by a spike relay. Fairly cheap too.

As for the pressure, we've figured out that all you need is a normal pressure switch. So that's usually 115psi-120psi. Between the pumps and the air tank reservoir add a pressure regulator. You can regulate the pressure and know what the pressure will be at, and the OI will receive the shut off from the pressure switch as you normally would.

I don't know if that's been posted before or not, I didn't have time to read all 60+ posts on this thread, i was just too excited to post. So if someone else DID post this, I do apologize.

Bryan Gallo