Originally Posted by Al Skierkiewicz (Post 1385290)

OK, to be a stickler here, the Pneumatic Rules also include the 2014 FRC Pneumatics Manual which lists the specifications for the switch as "This switch is normally closed. The switches will open at approximately 115 psi and will not close again until the pressure drops to approximately 95 psi." In addition paragraph 4 of Section 4, "In addition, another intent of these rules is to have all energy sources and active actuation systems on the ROBOT (e.g. batteries, compressors, motors, servos, cylinders, and their controllers) drawn from a well-defined set of options. This is to ensure that all Teams have access to the same actuation resources, and to ensure that the Inspectors are able to accurately assess the legality of a given part."
For those reasons, adjustable pressure switches are deemed illegal, in particular any switch that can be set to a pressure higher than 115 psi. Throughout section 4.10 the Nason Pressure switch is shown as the pressure switch. BTW, I am betting that the OP is using a standard robot pressure gauge that may or may not be accurate. Tapping on several (hundred) over the years have caused them to change pressure displayed.

Originally Posted by FrankJ (Post 1385298)

Where in the rules is the pneumatic manual referenced? It seems to be more guidance than a rule. If it going to be taken as rule then it needs to be incorporated into the rules at least by reference so team know they are a rule.

R81 only says stored pressure needs the be below 120 PSI.
The Robot inspection checklist under power on checks specifies the compressor turns at about 120 PSI.
The Q&A Q459 specifically allows pressure switches to be calibrated if intended to be so by the manufacture.
All of this seems to be in conflict with pneumatic manual.

Using cheap non calibrated gauges to verify pressure settings, particularly safeties is a separate thread.

Originally Posted by Alpha Beta (Post 1385261)

Q258 Allows any pressure switch that meets the pneumatic rules.

Q459 Allows switches to be callibrated per manufacturer-provided instructions. It does not allow the end user to adjust a switch that the manufacturer did not intend to be adjustable.

R88 calls out the requirements for the pressure switch. The adjust-ability of the switch is not specified.



Doing a quick control-F search on the game manual, the only time the word Nason showed up was in the word Panasonic when referencing allowable batteries. When searching Q&A only 258 and 459 mention the word Nason. Where does the phrase "must be the same or equivilant to the Nason pressure switch." come from. I can't seem to find it.

I heard there was an inspector who successfully got adjustable pressure switches removed from a robot at Champs. Clearly it was not a universal interpretation amongst inspectors, as we ran with this.

Originally Posted by ArtemusMaximus (Post 1384967)

Can pressure switch be replaced with this pressure sensor and then calibrate within the code?
http://www.digikey.com/product-searc...ds=734-1003-ND

Originally Posted by Steve W (Post 1385908)

The inspector was actually Big Al and Frank was also in on the decision I believe.

Originally Posted by Al Skierkiewicz (Post 1386244)

The pressure switch that is being discussed was resettable in seconds, without tools, to a max of 145 psi. For those reasons and others that I discussed with the team, it neither meets the rules, the Q&A nor the intent.

Originally Posted by Al Skierkiewicz (Post 1386429)

Art,
We are not saying that the team intended to increase pressure, nor are we saying that they would recalibrate the relief valve. Inspectors do need to make interpretations all the time. This is only one of a hundred + that I made this season. A few were... Are tywraps suitable fasteners for springs? Can a team use barbells for ballast? Is a 16 pound mallet legal for a ball shooter? Can I use a leg lamp from the Christmas Story as a kicker? Can I bring in my protobot and my alternate drive base in addition to my bagged robot? Can I use a ratchet wrench as a mechanism for my shooter release device? Can I use an electro magnet that we rewound for use at 12 volts? When I replace the nylon stockings on my leg lamp that are damaged during a match, is that a repair or modification? Can I put this "mini=sun" on my robot to help my vision system? Can I make a 300 volt power supply to power the neon lights our sponsor would like to see on the robot? Can I write my own protocol software, I don't like that which is provided? These are in addition to the questions asked on the Q&A.

Originally Posted by Al Skierkiewicz (Post 1386491)

Might be more like:

R78
If pneumatic COMPONENTS are used, the following items are required as part of the pneumatic circuit and must be
used in accordance with this section, as illustrated in Figure 4-15.
A. Compressor
B. Pressure Relief Valve, calibrated for release at 125 psi.
C. Pressure Switch, Nason #SM-2B-115R/443 or identical specification (115-120 psi), non-adjustable, equivalent.
D. Pressure Vent Plug
E. “Stored” Pressure Gauge (upstream from Primary Regulator)
F. “Working” Pressure Gauge (downstream from Primary Regulator)
G. “Working” Pressure Regulator

For everyone, the part number shown above is the device sold by AndyMark and the part number refers to a set point of 115 psi. The data sheet specifies the set point at +/- 1 psi with a differential (hysteresis) of 8-16%. That translates to turn compressor back on when the pressure falls below 97-107 psi.
While it is hard to see due to the formatting of the pdf, remember...
R81
“Stored” air pressure on the ROBOT must be no greater than 120 psi.