NAC445A.6725. Cross-connections and backflow: Use of vacuum breakers.

     1. An atmospheric vacuum breaker or pressure vacuum breaker may be used only for protection against pollution or contamination under conditions of backsiphonage.

     2. If an atmospheric vacuum breaker is used:

     (a) The vacuum breaker must be installed not less than 6 vertical inches above the highest point of the downstream piping.

     (b) Any associated shutoff valve must be installed upstream from the vacuum breaker.

     (c) The vacuum breaker must not be subjected to operating pressure for more than 12 hours in any 24-hour period.

     (d) Flow from the protected fixture must be to the atmosphere.

     3. If a pressure vacuum breaker is used, the vacuum breaker:

     (a) Must be installed:

          (1) Upstream from the terminal shutoff valve; and

          (2) Not less than 12 vertical inches above the highest point of the downstream outlet, valve or piping.

     (b) Must not be installed at a location where backpressure will occur.

     (Added to NAC by Bd. of Health, eff. 2-20-97)