Ray,
Those are the ball valves I was talking about. They have some useful characteristics:
1) The valve body is made of metal, not plastic.
2) The ball valve is full flow
3) The ball valve will tolerate higher pressures
1), 2) and 3) mean that the values are well suited to hot climates like Arizona, where the sun will break down plastic. A potential issue is the electronics and plastic electronics housing, but that can be mitigated by shade, paint and a valve box.
4) The ball valve is cheaper than plastic valves when bought through Alibaba.
5) It is, as you mentioned, a “fail close” design.
6) No rubber diaphragms to repair constantly. If a system contains a lot of valves, this is a regular chore, especially at higher water line pressures.
For those of us who have to implement a system with a lot of valves, ball valves like these are worth looking at. Pair them with a two-wire control system and the result is an easily manageable and scalable system.