R68: One and only one compressor
 

The way I see it, R68 is extremely clear that a second compressor (such as another ViAir on the cart, or in the pit, or a shop [120 V AC] compressor) anywhere at the competition is just not allowed.

Am I mis-reading this rule?

Anyone want to take bets on how many teams attempt to use more than "one and only one" compressor at competition?

Re: R68: One and only one compressor
 

I'm betting 1/20. That seems to be the average rate of teams I have seen trying to use a globe motor / more than one compressor / other illegal part in the past. Teams that haven't read the manual in the past will most likely continue not doing so at similar rates.

Of course, I may be surprised this year.

Re: R68: One and only one compressor
 

There has always been a debate about additional compressors and the way I understand the rule is you may only have 1 compressor supply the air for the robot. That counts for pre-match, post-match, during a match and in the pit.


What I think the rule allows is for teams to use a shop compressor for tools and other thing besides the robot.

Re: R68: One and only one compressor
 

Anyone know why this is a rule?

Re: R68: One and only one compressor
 

I think it will actually be very low this year, compared to previous years. Prototypes and process pics/vids I've seen so far are much more heavily reliant on motors than in the past... I'm guessing we'll see fewer teams with pneumatic s than normal.

Re: R68: One and only one compressor
 

Part of it is probably fairness, so teams with fewer funds or rookies have the same opportunities as teams that have been around a dozen years. Keep in mind rookies get a compressor in the rookie KoP, so we know that every team has access to at least that one, even if it is old.

Beyond that, I would say there's a big argument to be made for safety, simplicity and inspectability. We need to be able to ensure a system at competition is properly set up and controlled. We don't want compressors being run manually by hooking them straight to a battery. We don't want teams to have the ability to create a dangerous over-pressure situation just for a small advantage on the field. Having a regulated and fixed set up with one compressor and other required parts makes it a lot easier to ensure every team is being safe, and a lot easier to ensure everything is set up legally.

Keep in mind this is not a new rule. It's been in place as long as I've been Inspecting. For example, in 2010 (Breakaway) R75 stated " Compressed air for the pneumatic system on the ROBOT must be provided by one and only one compressor."

Re: R68: One and only one compressor
 

Don, I think there are a couple of points where I might differ with your interpretation of R68. Here is the rule:

R68
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.

First, in the event that a team suffers a complete failure of the robot compressor would you disallow them from replacing it with a like for like unmodified compressor from the spare parts station or from their own parts drawer?

Second, your interpretation fails to give any meaning to the words "on the ROBOT". IMO the rule is worded to clearly indicate that the stored compressed air in a robot's pneumatic tanks is to be provided by that robot's on-board or off-board compressor not by some other source. The purpose of the rule is, I believe, to disallow the use of a compressor identical to that of the robot's on-board compressor to fill the pneumatic tanks pre-match while keeping the on-board compressor cool and fresh for the match.

Finally, as worded, R68 clearly prohibits the use of a shop compressor for supplying compressed air to "the ROBOT" due to the voltage and flow rate specifications. Shop compressors are not prohibited from being present in the pits under this rule.

Re: R68: One and only one compressor
 

Interesting. In previous years, we have been told to remove our portable shop compressor from the venue.

Re: R68: One and only one compressor
 

Can't speak to your particular experience but electrical power limitations are present at some venues due to concerns about tripping breakers in the pits.

Re: R68: One and only one compressor
 

I highly doubt that! Spare parts are specifically permitted.

Yep, I see it the same way.

Correct. However, if a team were to be found to be using a shop compressor to fill their robot, OR if the venue had an issue (noise or power supply), the LRI would probably head around to all the teams with shop compressors to ask them very nicely to remove their compressors from the venue. And if a team failed to stop using their shop compressor to fill the robot after being asked once, I could certainly see them being told to remove the compressor from the venue immediately (as well as a possible red card for either uncivil behavior or for uninspected/illegal robot on the field).

Re: R68: One and only one compressor
 

Last year, I specifically asked a Q&A question about this. You can absolutely have more than one air compressor at a competition just like you can have more than 6 CIM motors at a competition. You can only have 6 CIMs on your robot at one time and you can only use one air compressor to put air into your robot...but you can have backups and you can use a different air compressor for different matches.

People always claim that this rule is clearly worded and yet there is always a discussion about interpretation.

Re: R68: One and only one compressor
 

I don't read it that way at all, for multiple reasons. First and foremost, the robot rules govern robots, not tools, except when a rule mentions a tool being used to affect a robot. General event rules governing what you may use as a tool fall are found in the administrative manual, and it contains no prohibition on compressors used as tools. (Obviously, for other reasons, you can't use some kinds of compressors at all.)

If the tool is intended to be used to affect a robot (e.g. to fill the robot's tanks), there's still no violation. The rules do not prohibit thoughtcrime.

If the tool is used to affect a robot in an illegal way, they should fail inspection; if no gameplay is involved, there is no penalty for that, other than the opportunity cost of having to get it reinspected. So if a team uses a compressor illegally, and is caught, they can refill legally to the officials' satisfaction, whether or not the offending device remains in the building (and assuming that it's not a materials/schedule issue that concerns what may be brought to an event).

If the tool is used to affect a robot that is involved in gameplay, the gameplay penalties can be invoked—but even then, none of them prescribe that the offending device be removed from the building.

Re: R68: One and only one compressor
 

The tangential issue of spare parts under R68 is also a bit complicated (and has been discussed in the context of previous years rules).

As the relevant rules are mostly unchanged, my contention remains that assuming you can bypass part quantity limits to install a spare (this is clearly past and present practice regarding motors, for example), there is uncertainty as to whether air already legally stored in the tanks ceases to comply with R68, and thus R24.

Basically: if you are entitled to bypass the R68 limit of 1 to install a spare compressor, what necessarily prohibits you from bypassing the same limit as a result of the same act to use the air supplied by the first one? It's the same clause of the same rule, and yet to prohibit the air would be to enforce and overlook it simultaneously.

Re: R68: One and only one compressor
 

Q&A responses from previous years do not have bearing on the current year.

If you want further clarification post a question to the current Q&A.

Re: R68: One and only one compressor
 

How would you replace a compressor without dumping the air first? Sure, it's possible with an off board compressor, but an on-board one, which covers probably 99% of the compressors I see at competition...

Re: R68: One and only one compressor
 

Easy, just pinch off the feed line between the compressor and tank(s). A pair of smooth jaw vice grips works or even folding the tubing back on itself to pinch it off. Just a word of caution is in order, that it is possible to weaken the pinched line which may cause it to burst later. Kind of reminds me of the white air tanks that would blow up under any kind of impact.

Re: R68: One and only one compressor
 

I wish they would allow you to fill your system up to 120 without using your on-board compressor...would save some abuse and that extreme heat.
-Ronnie

Re: R68: One and only one compressor
 

I suppose I can give a small list of things that I believe do not meet this rule as written. This is by no means all inclusive but it is most definitely things that I believe are illegal and that I have seen in use at events in just the last two years.

Items that I see as violations of current and past pneumatics rules...
1. Uncontrolled shop compressors.
2. Large storage tank (5 gallon +), filled by unknown compressor and used to then fill robot storage.
3. Robot compressor on cart connected to a robot battery and run indefinitely.
4. Shop compressor stored behind a curtain and used during queuing to fill robot.
5. A jumper cable to bypass robot control of on board compressor and connect directly to robot battery.
6. Bypassing pressure switch and running compressor continuously in queue.
7. Compressor of varying type, on robot cart connected to car battery and used in addition to robot compressor with no pressure control.
8. Legal robot compressor on cart, used in addition to on board compressor.
9. A separate cRio and robot battery used to run the robot compressor.

While some of these incidents were also accompanied by resetting of the over pressure valve, most did have that protection in place and working on the robot. In some cases, observed pressure was in excess of 150 psi.
Regardless of your opinion on the subject, this rule intends that any air stored on your robot comes from one legal compressor of the type specified. That air is generated from the one legal compressor that is mounted on your robot or if none is mounted on the robot then one can be used that is off board. In all cases, the one compressor must be run using a robot battery, controlled by the robot's RoboRio by sensing the one legal pressure switch to determine system storage pressure of 120 psi max. The pneumatic system of your robot is legal to use when it is inspected and approved by the inspector (subject to reinspection at any time by Head Ref, FTA, and/or Inspector). The intact pneumatic system as inspected is the only legal means of providing air storage on your robot. If you are unsure at competition, please ask the LRI for advice.
If it helps, this rule can be interpreted as "only those items that are inspected are legal for use on your robot". All of those items listed do not meet that criteria.

Re: R68: One and only one compressor
 

Does this constitute an official interpretation of the rule?

Re: R68: One and only one compressor
 

What does this mean?

Re: R68: One and only one compressor
 

We got hassled about doing this even though we had witnesses that were event officials watch us suffer through filling a 1 gallon spare air tank with the robot compressor a few years back. All it takes is another team to complain thinking it is unfair for offboard storage to be not worth the benefits. We really didn't see any harm in doing that as it technically followed the rules, but New Hampshire was called and they said storing air off the robot was not okay.

Re: R68: One and only one compressor
 

John,
As always the Q&A is the decider. The above list is items that I have personally seen that were also deemed illegal in the past.

Adam,
Uncontrolled is exactly what I saw, no method used for shutting off the compressor. It ran until a pop-off valve operated. The original owners had bypassed the switch because of some issue. The leaking air was one of things that alerted event people of the compressor.

BTW, LRIs are not the only people that have to be satisfied at an event. We merely interpret the robot rules of Section 4. UL Safety people, event staff, venue staff and FIRST staff present at the event, all can and will step in when safety concerns are present.

Re: R68: One and only one compressor
 

I'm surprised that if headquarters feels it's illegal to store air off the robot that they wouldn't state it more clearly in the manual. Did you get the impression that they made their ruling based on safety, or was it for some other reason?

Re: R68: One and only one compressor
 

Pete,
R74 & R75 essentially show that.

Re: R68: One and only one compressor
 

As I read R68, and other associated rules in the manual surrounding compressors I see absolutely no rules preventing a team from having a compressor in their pit that is not used for the robot.

Emphasis mine. As far as I can tell, it is ONLY up to either the VENUE to disallow the use of a shop compressor for non robot powering service or the event staff if they deem that a team is unsafely using it (such as using it to clean off their tables, etc.) I have not found any other tournament rules that explicitly disallow a team from bringing a shop air compressor into their pit for purposes other than filling their robot's air tanks.

- Nick

Re: R68: One and only one compressor
 

It is stated more clearly this year - R70 states:
Can't be much clearer this year!. Previous years, it was not stated clearly, but implied through the pneumatic diagrams and list of components for on board/ off board setups.

Re: R68: One and only one compressor
 

It was clarified last year during Q&A for 2014. Pneumatic rules have always been very restrictive & rigidly interpreted. Didn't stop exploding tanks. :ahh:

Re: R68: One and only one compressor
 

Emphasis mine. It's still very clear to me that you can have an air compressor in your pit for shop tools, and not the robot.

-Nick

Re: R68: One and only one compressor
 

Thanks Jon! There have been a few rules in this year's manual that are far clearer than they previously were. Very happy about that :) I must have skimmed over R70 since we do all our pneumatics onboard anyway.

Re: R68: One and only one compressor
 

I agree Nick. My original post was unclear in that I was discussing air on the robot only.

Shop air depends on the venue; many are power-limited and even a small compressor could pop a breaker, although some have plenty of power and are OK with big compressors used for tools and harassing freshmen.

The point is, air on the robot is to be supplied by only one compressor. You can't use a second compressor to add air to the robot, regardless of how much better for your robot you feel it will be.

Re: R68: One and only one compressor
 

Thanks for clarifying Don. Totally agree.