Pneumatic Tanks

#1

hi my team will be a 5 year team now and have always had problems with pneumatics
we have just seen some teams using portable air tanks like in shops and was wondering is there anything you have to do to them before putting them on the robot other then hook it into the system

#2

For competition, using shop air or air compressed offboard the robot is not allowed. See this year’s R86 (and R85 and perhaps others). For practice/non competition purposes, essentially just make sure that you are doing things safely, e.g. not pressurizing anything over its ratings.

R86. Throughout an event, compressed air on the ROBOT must be provided by its one onboard compressor only. Compressor specifications must not exceed nominal 1.10 cfm (~519 cm3/s) flow rate @ 12VDC.

A ROBOT’S compressor may be substituted by another compressor, but a ROBOT may only have one designated compressor at a time, and all compressed air on the ROBOT must be sourced from a single compressor.

#3

Not particularly, other than adding fittings to link them to your system, since you need both inflow and outflow to the same tank. Since you’re automatically limited in the pressures you’re allowed to maintain in a pneumatic system on either the high pressure or the working pressure side, the only real advantage from using larger tanks is the increased volume of air available. That may be important if you’re driving large actuators, but is usually not an advantage for most pneumatic systems. It’s usually easier and lighter weight to just link together several of the standard Clippard plastic tanks to get more storage. You really don’t need a larger metal tank that’s designed for higher pressures than you’re allowed to use.

#4

ok are there any bigger tanks then the ones on andy mark becaus we had 8 of them hooked together and would run out at the end

#5

Any tank rated for 125 psi plus is legal.

1 Like
#6

that goes to 125 or has to be 125 and above

#7

You can use any COTs tank that is rated up to 125 PSI. We used a 4 Liter ARB tank this year which weighed a bit more I believe than that many in clippards, but with less fittings to deal with, it was worth it to help against leaks. This was the first time in a long time the team has done pneumatics (nobody is left from the last time we did pneumatics anyways) and had a couple leaks during season but nothing major, most stemmed from the fact we had a lot of Tees directly coming off our manifold almost, not allowing straight tubes. We would use the ARB tank again, and most likely will.

#8

where did you guys get the tank from

#9

Amazon.
ARB 171601 Steel Tank https://www.amazon.com/dp/B00IAAU66K/ref=cm_sw_r_cp_apa_i_I-W1CbS1QH0BN

It is NOT a steel tank as the ad lists, it is indeed aluminum.

#10

did you guys hook it up to the compressor on the robot or did you guys fill it up off board

#11

This year, offboard compressors were not legal so all air tanks had to be filled with the onboard compressor.

1 Like
#12

The biggest thing you can do to help with leaks is to have clean cuts on tubes. Don’t use scissors, use a proper tube cutter. It makes a huge difference.

7 Likes
#13

Plus minimize fittings. Avoid using union fittings if you can. If possible, using a manifold setup for solenoids rather than individuals. Leaks pretty much only happen at fittings, and while having clean cut tubes can help prevent it, just not having additional cuts is one better.

1 Like
#14

Re wrap your fittings each time too.

#15

Our team has no manifold this year due to weight limitations, and used 3 solenoids with tube connections. We had several pistons tied to each solenoid line, and three pneumatic tanks.

We also had almost no leakage - we could leave our robot pressurized overnight and come back and still have a good portion of the pressure remaining. Fittings are actually extremely reliable as long as you use plumbers tape and have straight tube cuts.

#16

Before we all start troubleshooting…

@tylerblockbuster, can you elaborate on what your problems with pneumatics have been? I know you mentioned running out of air at the end of the match even with 8 AM tanks. Sometimes that’s just a function of having a lot of pneumatics or very large cylinders, other times it’s leaks, and still other times there’s something else going on.

Would you be able to describe what cylinders you have onboard in terms of size and actuations per match (that is, how much any given cylinder is used)?

True story, but old: I once saw a team, now defunct, who used 2’ throw x 2" bore cyclinders, two of them, to open a gate and let game pieces gravity-flow out. For reference, this was back well before plastic tanks were able to be used–I want to say there was a limit on number of metal tanks that could be used as well. (My team at the time was in our second straight year of zero pneumatics–we used them before and after those two, but for whatever reason we didn’t need them that yeear.)

1 Like
#17

Remember to check for leaks in both positions of each of the pistons. Only one side of the piston is pressurized at a time, and if you don’t check both positions, you could have a leak in the other position and not know about it because you only ever use that position during a match.

There are some good calculators out there that will tell you what your stored and working pressure is for a given number of piston motions for a given size piston or set of pistons. You may want to run your design through one of those calculators to see if you are using too much air for all your systems. If you are, then, as others have suggested, you may want to look for areas where you can use smaller bore pistons or shorter stroke.

Remember that with a large amount of stored air, you will need a long time to pressurize before a match. This can be very painful if you are eliminations with relatively quick turns between matches. While adding more storage may get you to the end of the match with sufficient air, it might result in other problems. So it is best to try to design your system to use the least amount of air possible and then size your storage as small as you can. Ideally, the compressor should be able to top off the tanks during the match so that it is not running the whole match. But I have seen many times when the compressor does run the whole match.

2 Likes
#18

where would i find these calculators and also our little pistons we tried kept bending are there ways to strengthen them because if we can i could use smaller pistons

#19

So the question I have is, how were your cylinders set up? There’s lots of ways to make cylinders not bend, and the best one is to make sure that they’re only taking force along their line of travel, not laterally across it.

#20

PHD 4x4, 3/4 in. Bore, 4 in. Stroke Cylinder we ran four of these and a couple of smaller ones with one 4 ft one we only used at the end