Legal compressors?

[Maine951]

My team is trying to look away from the small compressor. The am-2005 on andy mark. We have gone through 2 of them last year and 1 in the previous year. We don't want to go to the bigger compressor that has been with first due to the weight of it. Are there other legal compressors we can use? Or is it any compressor as long as it doesnt go over the cfm?

[jee7s]

Per R79:

R79
Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12VDC, 1.05 cfm flow rate.

So, if it's powered by 12VDC with max flow rate of 1.05cfm, you're in business.

But, the better question is why do you have compressor failures? My team has used the same compressor for three years now. It's a Viair...I assume that's what you mean by "small compressor". Are you overheating it? I've run into a couple teams that ran the compressor well past its duty cycle (the Viair Spec says 9% -- yes, that's NINE percent) who ran into trouble. One large fan blowing on the top heatsink goes a long way to keeping that motor cool.

[DonRotolo]

Originally Posted by jee7s

One large fan blowing on the top heatsink goes a long way to keeping that motor cool.

FWIW, it isn't the motor that gets so hot, it is the compressor cylinder (head & piston).

[Joe Ross]

The Thomas 215 compressor also meets the CFM requirements.

[yash101]

Originally Posted by DonRotolo

FWIW, it isn't the motor that gets so hot, it is the compressor cylinder (head & piston).

That makes sense because when you compress gasses (and solids/liquids), each molecule has heat. When there are a ton of molecules in one place, the heat adds up until it is unbelievably high. Entropy takes away most of the heat via the heat sink. However, active cooling is something that can just almost always aid in passive cooling! The motor will typically be a quite efficient one that shouldn't get too hot. The problems start occurring when the motor is so close to the piston that the heat is moved to the [cooler] motor because of entropy. This is similar to what happens in the air conditioner. The gas is compressed, taking away the heat. that way, in the condensor, it is decompressed, leaving you with supercooled gas to cool the air using!

[Nirvash]

Originally Posted by yash101

That makes sense because when you compress gasses (and solids/liquids), each molecule has heat. When there are a ton of molecules in one place, the heat adds up until it is unbelievably high. Entropy takes away most of the heat via the heat sink. However, active cooling is something that can just almost always aid in passive cooling! The motor will typically be a quite efficient one that shouldn't get too hot. The problems start occurring when the motor is so close to the piston that the heat is moved to the [cooler] motor because of entropy. This is similar to what happens in the air conditioner. The gas is compressed, taking away the heat. that way, in the condensor, it is decompressed, leaving you with supercooled gas to cool the air using!

As long the the compressor manufactures used proper high temperature bearings, any heat transfer between the head, piston rod and eccentric bearing is negligible. The failure mode for most compressors is either the cup (part that glides and seals between the piston and the piston sleeve) wearing prematurely due to heat, or the sleeve flaking due to being overheated which damages the cup.
It is worth to note, that with someone who knows what they are doing, these parts are easy to replace.

[Trent B]

If you haven't I would take advantage of positioning one of the large papst fans provided in the kit of parts at the top heatsink. It made the difference between near instantaneous burns and being uncomfortable to hold onto for a couple of seconds last year in our pneumatic intensive robot.

It definitely presents a strong case for active cooling, and our compressor was (and still is) reliable for 2 competitions, 2 off-seasons and a build-season scrimmage.

[sanddrag]

We've gotten them hot enough to melt pneumatic tubing about an inch away from the head, but we've never had one fail, even running the robot almost nonstop for several hours.

[colin340]

i want to say in 2012 the holycows????? ran a car seat one, that inflated a lumbar support.

[Cory]

We have used these two compressors:

http://www.gd-thomas.com/productlist.aspx?id=10124&tp=p (the Thomas 215 that Joe mentioned)

http://www.gd-thomas.com/productlist.aspx?id=10120&tp=p

[Mike Schreiber]

Originally Posted by Cory

We have used these two compressors:

http://www.gd-thomas.com/productlist.aspx?id=10124&tp=p (the Thomas 215 that Joe mentioned)

http://www.gd-thomas.com/productlist.aspx?id=10120&tp=p

Any particular reason for this? Advantages/Disadvantages?

[Cory]

Originally Posted by Mike Schreiber

Any particular reason for this? Advantages/Disadvantages?

They are substantially lighter than the previous KOP compressors.

[Jon Stratis]

Originally Posted by Nirvash

It is worth to note, that with someone who knows what they are doing, these parts are easy to replace.

and doing so would make the compressor illegal for use on a competition robot, per R76: "All pneumatic COMPONENTS must be used in their original, unaltered condition." Repairs are technically alterations, and there's no way for a third party (ie an inspector) to know if you have sufficient knowledge/experience to perform the repairs and result in a functionally equivalent and safe compressor.

[Nirvash]

Originally Posted by Jon Stratis

and doing so would make the compressor illegal for use on a competition robot, per R76: "All pneumatic COMPONENTS must be used in their original, unaltered condition." Repairs are technically alterations, and there's no way for a third party (ie an inspector) to know if you have sufficient knowledge/experience to perform the repairs and result in a functionally equivalent and safe compressor.

Ah, I work with electronics too much and forget that repair rule didn't extend beyond electronics.
Sadly restrictive there, but a rebuild kit is about half the cost of the compressor new, so there isn't too much savings anyway.

[Rosiebotboss]

Be advised if youuse a "non KOP" compressor that meets R79, make sure you bring the manufacturer's data sheet to your competition to prove to the inspector that the 12VDC and 1.05 cfm is not exceeded.