[Bill Tompkins]

This will be my only post, and I am only going to comment on the rules and the need to comply with them.

[R73] Compressed air on the Robot must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12V, 1.05 cfm flow rate, 120 psi maximum working pressure. Off-board compressors must be controlled and powered by the Robot.

• Whether or not anyone feels these are valid or needed rules they are in fact, the rules. Rules are put in place by FIRST for the safety of everyone and to keep the matches competitive. In NASCAR you could go faster and further with a bigger engine and fuel tank but it is against the rules. You are given a bunch of parts and set of restrains (rules). You are then asked to build a robot and compete in adherence of these rules. This is the game.

• Relief Valves (16-004-011) help prevent over-charging but too often these do not work probably and can be tampered with. As part of the robot’s inspection the safety Relief Valve is checked. However, it can be changed easily with a wrench. In addition, the Relief Valve does have limitations in its ability to release pressure. If you are adding pressure faster than the Relief Valve can release it then you have an explosion. A FIRST specification for on-board and off-board compressors is 1.05cfm. The picture of the compressor shown in this thread has 4 to 5 times that flow rate. The Relief Valve and pneumatics systems used in FRC are designed to safely operate at the 1.05 flow rate. Exceeding this could be dangerous.

• A feedback path to the robot is required in order to shut the compressor down when the pressure gets too high. The Pressure Switch (SM-2B-115R/443) is designed to electrically open at 115psi and close at 95psi. This is also checked at the robot inspection. However, without feedback to the off-board compressor the entire volume of the compressor could be dump into the robot at high pressure and rate.

• Pressure gages have been known to stick. They are mechanical in nature and sometimes malfunction. This is the reason for the secondary protection of the Pressure Switch and the Relief Valve and the need to have feedback to any off-board sources. Just visually watching an air gage and assuming the pressure reading is correct is inherently dangerous.

• Items not part of the KOP are required to be inspected for compliance to the rules and safety. If an off-board compressor not part of the KOP were to be used it should have been inspected, its operation demonstrated, noted on the inspection sheet and would become part of the BOM. It also becomes part of the maximum unit cost restriction.

Sorry, the second sentence should have read, "If a compressor not part of the KOP were to be used it should be inspected, its operation demonstrated, noted on the inspection sheet and would become part of the BOM. "

• When charging the air tanks the battery is drained. The larger the on-board air storage capacity the larger the drain on the battery and the longer it takes to charge the tank. This is a design consideration trade-off. You choose to have the added air capacity knowing your battery and air charge time will be inhibited. This is the reason why off-board compressors need to run of the robot’s battery. Not doing so gives a team an unfair advantage.

Answering a question in one of the responses, Yes, you do have the option of changing batteries between matches (assuming you have them available).

• The time periods between finals matches are timed. You have the option of using timeouts if additional time is required. If your robot cannot be serviced in this allowed time period then you just have to do the best you can. This goes for everything from broken wheels and chains to battery changes and air charging. The design trade-off mentioned above gives you more air to work with on the field but lengthens your air charging time. Given the short time period between finals matches you may not have the time to fully charge you tanks. However, supplementing this with an additional air source is a violation of the [R73].

• "Compressed air on the Robot must be provided by one and only one compressor". This part of the rule is pretty clear.

In closing, this “seemingly needless rule” is designed to keep things safe and competitive. We can debate (which I am not) whether breaking this and other rules gave a team an unfair advantage or whether they could have won without it. The fact is, having a secondary compressor on the field does violate the rules for all the reason mentioned above.

‘On the field’, the LRI reports to the FTA and the Head Referee about safety concerns and rules violations. If in question, the LRI could request a re-inspection of the Robot, gather materials needed to support a claim, request documentation of parts used, review the team’s BOM and check the team’s initial inspection report. When findings are complete the LRI then reports back to the FTA and Head Referee. In situations where a team has violated a rule or ruling multiple times the problem would probably be elevated to FIRST HQ. However in the end, the Head Referee has the last word on the field.