Legality of using a pressure sensor on the high pressure circuit?

[Kevin Selavko]

There is a pressure sensor included in the First Choice Kit of parts

Also

Pressure Switch
We have included a pressure switch manufactured by Nason. 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. This will allow you to turn off the compressor once
you are up to 115psi, saving power in the battery. It must be wired directly to a digital
input and ground port on the Digital Sidecar. No specific GPIO port is designated for the
pressure switch. The cRIO must be programmed to react to the GPIO port that is connected to the
pressure switch. The cRIO will activate the designated Spike Relay to turn the compressor “on” and
“off”. There is no default program in the cRIO to control the compressor power. Do not put the pressure
switch in series with the power supply to the compressor.

-http://www.usfirst.org/sites/default/files/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2013/2013FRCPneumaticsInfo_RevC.pdf

The only pneumatic system items permitted on 2013 FRC ROBOTS include the items listed below.
...
F. Pressure transducers, pressure gauges, and connecting fittings,

-R78 F