RP Backflow Device
When installing a new backflow or replacing a domestic backflow prevention assembly, please refer to Standard Drawing W-39 Reduced Pressure Backflow Device; for a fire service, please refer to Standard Drawing W-28: Fire Service-RPDA.
3" Fire Hydrant Meter
When using a 3" Fire Hydrant Meter, please refer to Standard Drawing W-40. A 3" Meter will require a backflow device if the water truck does not have an air gap, a hose will be hooked up and strung out along the ground or if there is any question on the usage of water and potential contamination to the public drinking water system.