u/jicamakick

I have a large system that has a high point elevation wise that keeps failing. I repaired a 4” mainline and replaced a 2” valve. The 90 before the valve was blown to pieces. So I repaired with schedule 80 fittings (shoulda done that from the beginning) and took more care when recharging the system and it failed again. I made sure to bleed out all the air, ran zone in question many times throughout the day. But it’s a big system, on a 19 acre park with 50+ valves and NO isolation valves which sucks. So to make a repair, I have to drain the entire main. My solution is to install an automatic relief valve because I believe air is somehow getting into the system, collecting at this high point, and busting the fittings. Thoughts? Advice on arv types? Brands? Installation?