Two Compressors
 

I have a question. Is it legal to use more than one compressor on the robot? I searched on CD and couldn't find an answer. Also when following the parts use flow chart I'm getting confused. If you consider the compressor a pnuematic item it seems to be allowed, but if you consider it a motor it isn't. We have several extra compressors since we aren't a rookie team. Does anyone have an answer. If there is an answer or an actual post I missed can someone please point it out to me.
The problem is we are using three large cylinders and the compressor and air tanks can't keep up. We even added extra lengths of tubing to increase storage. The two compressors will be wired separately with separate fuses but plumbed together. The max psi won't change but we will get increased volume to run the cylinders. This will also take the burden off of one compressor, and we also realize it will drain the battery quicker.
If anyone else has any other ideas I'm open to suggestions.

Thanks,
Jason

Re: Two Compressors
 

you may not use two compressors i know its in the rules somewhere i just dont have time to find it

Re: Two Compressors
 

im also pretty sure you can't use two cylinders.
also, there was a forum on using extra tubing as a 'kinda' air tank. it turned out that that wasn't allowed. but if you reaaally need more storagetanks, you could use extra cylinders (not tanks) as a tank. i think.

Re: Two Compressors
 

actaully it doesnt matter how much storage you have, if your compressor cant keep up with your air demand

I take it you are using the pneumatics to move an arm or something, and when you move it back and forth a lot the tanks run dry?

in that case you want the hose between the compressor and the tanks as short as possible, so it have the least amount of resistance (more airflow) and you want to regulate the pressure to the cylinders as low as possible for the task you are performing, to use the least amount of air - also you might consider using a cylinder with a smaller diameter, that wont use as much air as a large one (if you dont need all that force)

BTW - putting extra cylinders in your system WONT give you more capacity because they are past the regulators, you would have to put them on the high pressure side of the regulator to store air - and that is against the rules.

Putting extra cylinders in your system will keep your pressure from dropping as low as it would without them, but it wont let you cycle your clinders any faster, because the only air coming into the system is through the compressor. If you 'need' 60 psi then you cant get it by using extra cylinders as storage.

Re: Two Compressors
 

KenWittlief, you're right. i was actually considering using more cylinders as tanks. good thing i posted a mistake :D thanks!

Re: Two Compressors
 

That is not entirly true. Although the cylenders would only store 60 PSI, they would have increased volume on the system. More volume means that the pressure that exists when the active cylender is extended will be more. More volume will always help.

Re: Two Compressors
 

no - if you need 60 psi on your active cylinders, then the extra cylinders will only be holding 60 psi - so they cant source any air that wont have to be replaced by the compressor - so it will take LONGER for your regulated side to get back up to 60 psi

cause the compressor will have to fill the cylinder that you moved and the unused ones that are just sitting there. Without the extra cylinders the pressure would have dropped lower in a smaller volume of space, and the compressor would fill the space faster (due to the lower backpressure). With the extra cylinders in there, the pressure wont drop as low, so the compressor has to pump the same amount of air back in, but at a higher back pressure.

To use extra cylinders as storage you would have to use two regulators - putting the extra ones at 60psi, and using the active ones at something less, probabally 30psi for the extra ones to do any good.

and that will still only help you if you dont use the pnuematics for a while, then you use them alot for a minute, then you dont use them for a while again.

Re: Two Compressors
 

now that I think of it, you are better off using a larger diameter cylinder at a lower working pressure than you are using a small diameter at a high pressure

because the compressor can pump more volume of air at the lower pressure - so that approach would let you cycle the cylinders more frequently.

if you are running larger cylinders at 30 PSI then the tanks can drop to 32 psi or so before your applied force starts to drop - and the compressor can get more volume at 30 than at 60

if you are running them at 60, then the compressor will start to fall behind at 62 psi,and will have a harder time keeping up with the demand.

Re: Two Compressors
 

i thought you are only aloud to use two storage tanks and then as many cylnders as you want

doesnt it say somewhere you can use only whay you are supplied wiht
ex
given two motors = only aloud two motors
2 storage tank = aloud only two storage tank
etc

Re: Two Compressors
 

I just want to thank everyone for their answers. Today was the first time we really got to test our robot with all the systems on it (currently 134#) pulling itself up to the bar. We noticed the compressor had to run almost continuously to keep up. We are aware it is slightly overweight since no weight reduction has been done yet. We didn't want to remove any "realestate" yet in case we have to change anything or remount anything in an area we milled out. We also shortened the tubing to normal lengths to neaten up the robot and very minor weight reduction. We also played around with psi and found out 40#'s is the lowest we can go. The reason I posted this is we were considering adding two compressors to increase volume which in turn would decrease system recharge time if we could get the weight down enough.

Re: Two Compressors
 

If you read rules <R01> <R54> and <R70> it is clear that only one compressor (pump) may be used on a robot.

:)

Aidan

Re: Two Compressors
 

For the purposes of your question, I believe that the compressor would be considered under the electronics/motor-pump thread of the parts use flowchart. Per the flowchart, multiple compressors would not be allowed (ie the second compressor did not come in the kit, and it would be an additional motor/solenoid/pump/actuator, and then lead to the "No, it cannot be used" answer. Since you are on a veteran team, you also know that in the past FIRST has made it pretty clear that you cannot use multiple pumps.

You should post the question to FIRST for the official answer, but I am fairly sure that it will not be allowed.

-dave

Re: Two Compressors
 

I agree with Dave that using a second kit pump would not be allowed.

However, FIRST has said that an off-the-shelf vacuum pump could be used as long as it's powered by a kit motor. Could an off-the-shelf compressor be used if it's powered by a kit motor?

That sounds like a good question to post on the Q&A.

Re: Two Compressors
 

i don't know if this is right or not, but by using a vacuum pump will not increase any air right? so things won't explode. maybe not. cuz the relief valve(is that what its called?) is ON the kit compressor

Re: Two Compressors
 

It's official, you're only allowed one compressor on the robot. I had the question posted to FIRST to get a definite answer and they responded.