[Kevin Sevcik]

To clarify my statement for everyone, you have to really look at the diagram on how the regulator works. There's two servo controlled valves in the regulator. Those valves control pressure in a chamber above the plunger in the regulator. That chamber acts like the spring in a mechanical regulator. Here's what happens in the different situations, I think:

Power loss: Servo valves close and stop operating. Chamber maintains pressure. Regulator does the standard relieving regulator thing at last setpoint pressure.

Control signal loss: Per data sheet, exhausting servo valve opens, sets chamber pressure to 0 psi, which makes it like a fully closed mechanical regulator. 0 psi output.

Power loss and Control signal loss: Probably depends on the order and mechanics of those servo valves. I'd guess the likely outcome is a slight decrease in setpoint, and then it maintains that pressure. I guess if the command signal drifts up before power loss, maybe a slight increase in setpoint?

The latter would be the most concerning for me. I wouldn't want this as a main regulator in case a weird wiring fault, short-circuit, or something put a bad voltage on the control line. It looks like 5V is the midpoint in the 1-145 psi range, which would be ~70 psi, so a wiring short on your analog output would put you out of spec. A bad wiring short might put it at max range and dump 120 psi into your system. With mechanical regulators, inspectors can at least be fairly confident that once they're set, they're not going to randomly change. That's not really the case with an electronically controlled regulator.