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#1
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Re: Off robot air compressor
This is one of the most heated items of the robot build over the last few years. Many people have brought up safety and related issues and a variety of other topics of what might be and what could be and what might fail. So, as an inspector and someone who has used both high and low pressure air supply for a variety of different tasks here are some things to consider...
I have seen injuries caused by failures of tubing due to over pressure, I have seen pressure regulators fail as open circuit, dumping high side pressure directly into the system. I have seen hoses flailing through the air under pressure, one actually knocking over a production line. I have found pressure relief valves that fail to open and pressure vessels that fail for any of a number of reasons. I have, as inspector, seen teams who thought it was OK to plug the compressor directly to a battery and watch the pressure guage and yank the power when they thought it was the right time. I have come across at least one team who had a car battery in their compressor rig with a switch and nothing else (breakers or fuses and certainly no pressure control). I have seen teams bring the 1/2 horsepower compressor out of their garage (capable of powering air tools) with a 2-1/2 gallon tank, to fill their robot and used the exhaust valve to regulate the pressure applied to the system. I have seen teams who didn't know how to plumb in the pressure guage and so left it off, same for the pressure exhaust valve. I have seen teams who did not know how to terminate tubing or to know that it was securely seated in the fittings. All of this and I am not even mentioning the use of pistons in dangerous ways. In fairness, I have seen equally destructive practices on mechanical systems and electrical systems. That is why we inspect. Nasa is an organization that "backs up the back up" as so many others where safety is concerned. In this case, the pressure switch and RC/spike combination is backed up by the pressure relief valve on the compressor which in turn is backed up by the inspection team performing a check that all works as normal. So with these experiences in mind I do not see the rules for compressor use on or off the robot as excessive. |
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#2
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Re: Off robot air compressor
Al, that last post covers the topic very well.
I only want to add, for the benefit of those who may not have met Al at an FRC event yet, that he is one of the most experienced and graciously professional volunteers associated with FIRST. The view that he expresses above is directly in line with the stated intention of FIRST, reinforced by increased support in recent seasons, to make safety the top priority. Because of this am confident that the off-robot compressor rules (conservative as they may be) will be applied as written at all 2007 FRC events. All teams should plan and design their robots accordingly. |
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#3
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Re: Off robot air compressor
Quote:
So, Al, I imagine it would be a bit awkward to connect and disconnect the compressor lead wires to and from the Spike Relay on the robot every time a team wants to charge up their system. If a team mounted a suitable 2-way quick disconnect connector (like the red Anderson connectors only not nearly as beefy) somewhere convenient near the periphery of the robot and ran red and black pigtail leads back from the connector to the Spike, would that be a legal setup? Just curious. 48 hasn't used pneumatics since 2003, and I haven't had the opportunity to observe how teams with offboard pumps legally charge up their systems. If the quick connector were legal, along with the air line from the pump, which would plug into the manual dump valve mounted to the accumulator, you'd have one power and one air connection. Plug in, open the valve, turn the robot on, charge up to full pressure, close the valve, power down the robot, remove the pump, and you're done. Correct? Last edited by Travis Hoffman : 11-01-2007 at 14:51. |
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#4
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Re: Off robot air compressor
Quote:
-dave |
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#5
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Re: Off robot air compressor
Quote:
The Anderson people make connectors for #10 wire that are small and the shells snap together to form as many contacts as you want and come in a vareity of colors. They are also available through the usual sources, Terminal Supply and Powerex. We have used them for years to make our robot modular. As to the rest of your post, YES. Tether, connect pump electrical and hose, open the exhaust valve, power the robot, wait until the pump is shut off under RC control, close the exhaust valve, shut down the robot and disconnect the electrical and hose from the outboard compressor. Check the pressure guage to make sure you are at no more than 125 PSI and go win a match. |
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#6
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Re: Off robot air compressor
Quote:
We also had a 2005 OI with a spare tether cable mounted to the frame holding the off-board compressor, so we didn't need to connect the "real" OI in order to get the robot to power up and run the compressor. The compressor frame had a spot to carry a battery as well; the drive team would charge up the pneumatics using the "pit" battery and quickly swap in a fully-charged "competition" battery. |
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