[EricH]

<R66-B> is your friend. (Also note <R66-C>.)

<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” COTSpneumatic devices rated by their manufacturers for working pressure of at least 125psi and used in their original, unaltered condition (except as required for assembly with other components).
[...]
B. Solenoid valves with a maximum ⅛” NPT port diameter, and a maximum Cv of 0.32 (if non-KOP valves are used, the team will be required to provide part documentation validating that the valves meet these constraints).
C. Solenoid valves that are rated for a maximum working pressure that is less than 125psi rating mandated above are permitted, however if employed, an additional pressure relief valve must be added to the low pressure side of the main regulator. The additional relief valve must be set to a lower pressure than the maximum pressure rating for the solenoid valve.

Instead of posting and waiting two hours for someone to see and respond, it may have been faster to read the Game Manual, Section 4.3.11, Pneumatic System.