I found this in a utility box in the front yard of a residential inspection. It does not appear to be downstream of the water meter between the meter and the home, but of course I could not verify.
Are these typically owned and maintained by the water department? If not, do they require maintenance? Do they have an average life span?
I was referring to installing the service line, saddle tap off the main, run copper tubing to the meter box/curb stop, then into the home/building. Never put any type of air relief valve on any of them.
Now if you are talking about irrigation systems, I’ve installed many types and brands of vacuum breakers, but they were always above ground. Minimum 24" above the highest sprinkler head.