[Bill_B]

Abrakadabra,
The pneumatic system can also get pressurized if an actuator is moved by its mechanical linkage being thwacked during a collision, for instance. Since you're going with off-board compressor, I presume that your actuators are not very big, so this isn't necessarily a problem for you. But you know rule makers. Cover the whole spectrum of possibility, if possible. I would put the relief valve into the robot's circuit even if the rules didn't require it. See [R72]