Creating the Lightest Pneumatic System

[FrankJ]

Hi Ed:
Aside from being a supporter of First AutomationDirect is a next day delivery for you & they have good stock.
The AutomationDirect valves are legal this year (Cv.78) The nominal pressure rating is 20-115 PSI. The way I read the rules means a separate relief valve unless you have something that says otherwise.

R77-D. Solenoid valves that are rated for a maximum working pressure that is less than 125 psi 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,

One reason to use a double solenoid valve is for spring center. The center position can either block or connect the A & B ports. So the cylinder will stop or flop when the solenoids are not powered. Another reason would if you want the valve to stay in the position last set rather than a spring return to the "off" position.