A potable water line supplies makeup water to a chemically treated boiler system and the connection is under continuous pressure. Which backflow prevention device is required?

Giải thích

Treated boiler water is a high hazard (health hazard) contaminant and the connection is under continuous pressure, which calls for a reduced pressure principle assembly. A double check assembly is only acceptable for low hazard, non-health, continuous pressure applications. An atmospheric vacuum breaker cannot be used under continuous pressure at all, and a hose bibb vacuum breaker is for hose outlets and protects only against back-siphonage.