Despite the fact that most air tanks are relatively inexpensive, I still decided to build my own. Most pneumatic kits from VEX (or comparable) come with a 1-1/2 x 4" aluminum air reservoir. These things are great and can hold up to ~100psi. I decided to build something slightly beefier.I have a love-hate relationship with Home Depot. I always have the sense that I'm getting ripped off. If I could just wait a few days and mail order, I could likely save a few bucks. Then on the other hand, Home Depot provides satisfaction for my compulsive "buy now" disorder. Needless to say I gave in. In this particular outing the pocket book was spared. I was able to rummage up the pieces and parts I need for under $25. 3"x24" pvc $2, 2 3" pvc caps $4, a few nylon quick fit hose adapters $4, a few feet of plastic hose $2 and a 300psi pressure gauge $7. Assembly took about 10 minutes. Now, be sure to let this sucker sit and dry before you go pressurizing it. And when that time comes, safty first, put your glasses on.
After testing is complete, it's time to power up the air muscles. Hopefully I can get a pressure switch and an air regulator installed soon.
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16 comments:
Hi David,
Great site, lots of valuable information here. Thanks for putting it up.
How has your experience been with the PVC tank? I've read on a couple of sites that it's potentially dangerous because the PVC will weaken over time (I doubt you've run into this thus far.) I've been looking for reservoir and seen suggestions about Copper or Black Pipe.
Hey Aaron, sorry for the super late delay. I did some research on PVC under pressure. Basically both schedule 40 and 80 must hold a minimum of 160psi. Also, by law, all PVC must have a pressure rating on it. I feel pretty confident that the 260psi PVC I have will withstand the 100psi I max it out at. Of course, black pipe and steel work just as well.
Can you give some more pictures of the air tank please. How has it worked is it as good as you wanted it to?
Anonymous- Sure. What angles of the tank would you like to see?
The tank works wonderfully and is constantly being "charged" and "discharged" with air at a rapid pace.
Well i guess its more that id like to see how you mounted the elbow and the valve in the side of the tank. I bought the same pieces today so that i can try and make an air tank. I might try to get elbows for the pvc and make a u shaped tank for the base of my robot but not sure yet. Have you put the tank on anything yet? Thank you.
DevilDog-
The small elbow pieces and gauge were all mounted in the tank by drilling very very tight holes and then using some special poly epoxy. Do not use PVC cement to connect your elbow pieces, etc. Reserve the PVC cement for the end caps.
Some additional photos can be found at:
http://files.davidjbarnes.com/PVC_Air_Tank/PVC_Air_Tank1.jpg
http://files.davidjbarnes.com/PVC_Air_Tank/PVC_Air_Tank2.jpg
http://files.davidjbarnes.com/PVC_Air_Tank/PVC_Air_Tank3.jpg
Also, you might want to consider getting a pressure switch. Viar makes some decent stuff: http://www.amazon.com/VIAIR-90111-Pressure-Switch-Relay/dp/B000FQ793A
Thanks, i got some epoxy ill try on it. I also got some solenoid switches for these that a friend gave me i think they are from SMC but i dont know how to wit=re them up, have you ever worked with these before?
SMC make great stuff, great prices too.
What kind of solenoids are they? Can you give me a part number and or a link? Are you interfacing the solenoids with a MCU? In either case, you'll need either a solenoid driver (5vdc logic, much like a servo) or a relay to step up your current out of the MCU pin.
Check out the Vex Pneumatics parts list here: http://www.quotientrobotics.com/2009/03/vex-robotics-pneumatic-robot-parts-list.html
Okay, i will try to give you the model numbers tommorrow because they are out in the garage, but i have a basic astamp i could useor i also wanted to know how to controll them with switches if i could.
Controlling the solenoids with a BS2 will not be a problem. You will however still need either the solenoid driver or a relay.
What kind of relay should i use?
It is going to depend on the solenoid's voltage.
Okay I have a SMC Solenoid Valve Model VZ3120
and a SMC Model VZ 3220
The solenoid VZ3120 (http://www.coastpneumatics.net/displayitem.php?keyword=VZ3120-2L-M5) is an AC valve. AC is fine, but doesn't seem optimal for a mobile robot. To control this valve from a micro, I would use this relay from SparkFun: http://www.sparkfun.com/commerce/product_info.php?products_id=101. Also, check out the relay PCB that is sold separately: http://www.sparkfun.com/commerce/product_info.php?products_id=9096
Okay, thank you for your help, hopefully i can get some of this stuff to work.
Complex control systems using valves requires an automatic control based input of an actuator. The actuator strokes the valve allowing the valve to be positioned accurately and allowing control over a variety of requirements.
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