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Question: 05-18 Code Section: 7 Date:

OBC 2006 Reference:

Question: What is an acceptable backflow prevention valve for an underground sprinkler system at a residence?

Interpretation: (On. Reg. 403/97) If it is determined from the installation of the lawn sprinkler system that the hazard is moderate and that protection is against back siphonage only, then the device required would be an Atmospheric Vacuum Breaker, a Double Check Valve Assembly or a Pressure Vacuum Breaker. However, if the degree of hazard is assessed at severe (ie. chemical systems included), then a Reduced Pressure Principle Backflow Preventer or a Pressure Vacuum Breaker would be required.

An example of a moderate hazard submitted by one of the committee members was that sprinkler heads were raised above adjacent ground and another member suggested that it was dependant on which side of the solenoid the backflow preventer was located under pressure or not?

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