I have seen a lot of threads this season about the 90 series compressors. Since the GDC is saying that they will not answer questions about specific components, I figured I would see if anyone here have more information about their legality.
The part that I am questionable about is that the maximum working pressure is only 120 PSI. R66 states that all pneumatic components must have a working pressure of at least 125psi. Does this mean we can not use these compressors?
Viair 92 specs
12-Volt
Permanent Magnetic Motor
Duty Cycle: 9% @ 100 PSI
Max. Working Pressure: 120 PSI
Amp Draw: 10 Amps
Inlet Filter Assembly Included
Inline Check Valve
Dimensions: 7.50" L x 2.10" W x 4.30" H
Net Weight: 2.50 lbs.
In addition to the items included in the KOP, pneumatic system items specifically permitted on 2011 FRC ROBOTS include the following items. All included items must be “off the shelf” COTS pneumatic devices rated by their manufacturers for working pressure of at least 125psi and burst pressure of 250psi, and used in their original, unaltered condition (except as required for assembly with other components).
I just found a conflict in the rules. R66 says a working pressure of 125 while R69 says a working pressure of 120psi. I will have to post in the Q & A about this.
Compressed air for the pneumatic system on the ROBOT must be provided by one and only one compressor. This compressor may be either the compressor from the KOP, or an equivalent compressor that does not exceed any of the KOP compressor performance specifications (specifically: nominal 12v, 1.03 cfm flow rate, 120psi maximum working pressure). Compressed air shall not come from any other source. Off-board compressors must be controlled and powered by the ROBOT.
I can see why you question this rule. Look at the system as supply and load. On the supply side is the compressor should not exceed 125 psi. All components on the load side of the system must be rated for at least 125 psi, and the pneumatic lines cannot exceed a certain inside diameter. This guards against over pressurizing the system that can cause burst of a component. I believe you are right in questioning “least” being used for the compressor. I think you should ask the question, quote the rule and emphasize the word “least”.
Does this rule mean that we can use a compressor that exceeds 125 psi?
I don’t believe this is their intent, and the main regulator will keep the system below the max pressure. But think what happens if that regulator fails, and the compressor produces higher pressures than the components can handle. Nice catch!:yikes:
Max intermittent pressure rating for the 90 series is 200psi.
120 psi maximum is what our robots are restricted to (by our properly set main regulator).
125 psi or greater is what the individual components have to be minimum rated for so we’re sure they don’t burst.
Our safety pressure relief valve vents excess pressure above 125psi.
This can be frustrating but you need to read <R66>:
In addition to the items included in the KOP, pneumatic system items specifically permitted on 2011 FRC ROBOTS include the following items. All included items must be “off the shelf” COTS pneumatic devices rated by their manufacturers for working pressure of at least 125psi and burst pressure of 250psi, and used in their original, unaltered condition (except as required for assembly with other components).
The 92C was supplied in the KOP therefore it is legal regardless of the manufacturer’s specifications. The 90C is being provided by you and you must provide documentation that it has a rated working pressure of at least 125 PSI.
I agree that, from an engineer’s and mentor’s perspective, it should be legal but, in order to get a uniform ruling by all inspectors at all events, someone needs to ask the GDC if a max intermittent pressure rating is sufficient to qualify under (working pressure of at least 125psi)…
The GDC ruling was that a compressor of identical specs may be used in place of the 090C, since the 092C and 095C only differ in their use of an external filter or a different bracket they are fine. If you are worried about passing inspection go to Viar’s website and do a screen print of the spec page for the 090C and the the one you are using.
The problem I have now is that technically, neither the 90C or 92C compressors actually are in compliance with R66.
In addition to the items included in the KOP, pneumatic system items specifically permitted on 2011 FRC ROBOTS include the following items. All included items must be “off the shelf” COTS pneumatic devices rated by their manufacturers for working pressure of at least 125psi and burst pressure of 250psi, and used in their original, unaltered condition (except as required for assembly with other components).
The working pressure of the compressors is 120psi and the only rating I found for the burst pressure was 200psi.
