R68: One and only one compressor

[Tem1514 Mentor]

Originally Posted by Jon Stratis

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...

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.

[RonnieS]

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

[Al Skierkiewicz]

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.

[JVN]

Originally Posted by Al Skierkiewicz

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.

Does this constitute an official interpretation of the rule?

[AdamHeard]

Originally Posted by Al Skierkiewicz

1. Uncontrolled shop compressors.

What does this mean?

[MrBasse]

Originally Posted by Al Skierkiewicz

2. Large storage tank (5 gallon +), filled by unknown compressor and used to then fill robot storage.

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.

[Al Skierkiewicz]

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.

[pntbll1313]

Originally Posted by MrBasse

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.

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?

[Al Skierkiewicz]

Pete,
R74 & R75 essentially show that.

[Nick Lawrence]

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.

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.

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

[Jon Stratis]

Originally Posted by pntbll1313

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?

It is stated more clearly this year - R70 states:

"Stored" air pressure on the ROBOT must be no greater than 120 psi. No stored air pressure intended for the ROBOT may be located off-board the ROBOT.

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.

[FrankJ]

Originally Posted by pntbll1313

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?

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

[Nick Lawrence]

Originally Posted by R70

"Stored" air pressure on the ROBOT must be no greater than 120 psi. No stored air pressure intended for the ROBOT may be located off-board the ROBOT.

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

[pntbll1313]

Originally Posted by Jon Stratis

It is stated more clearly this year - R70 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.

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.

[DonRotolo]

Originally Posted by Nick Lawrence

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.

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.