Proportion-Air’sQB3 electronic pressure regulator uses replaceable o-rings as seats andseals. All o-rings and seals are replaceable or exchangeable for new ordifferent elastomers. The o-rings for the intake and exhaust valves areset into a special grove that captures the o-ring but leaves it room tomove slightly and seal correctly for positive shutoff. The QB3incorporates an electronic pressure sensor that senses the downstreampressure at the work port for accurate regulation. The device accepts azero to 10 V or four to 20 mA command signal and provides an analogoutput that corresponds to the actual pressure.