1)Why do I need my "Backflow Prevention Assembly" tested annually? a. Backflow Prevention Assemblies and Devices break or wearout, just like the parts of a car. Backflow is the hydraulic condition that can cause an RP to stop working in the described normal flow pattern. Backflow can happen by either backpressure andor backsiphonage (b). Backpressureis a condition where a greater pressure is generated on the downstream than the upstream side of the assembly. This condition can happen for many reasons,pumps, thermal expansion, etc. By having your Backflow Prevention Assemblytested annually, you will help to ensure that the drinking water supplied toyour home remains safe. Because of this many lower mainland cities have createdthis By-law to help insure the safety of your drinking water. We have CertifiedTechnicians on our staff that have attended rigorous training, and are able totest your Backflow Prevention Assembly. Certified Technicians can inspect,test, repair or replace all Backflow Prevention Assemblies and Devices.
2) Why have I never had to test my Backflow before? a. When your Backflow was installed it was tested prior to plumbing inspection, but because of the volume of Backflow preventers being installed and the large number ofexisting Backflow preventers in various lower mainland cities it is not easyfor municipalities to keep you informed of when your Backflow is due to betested. However, due to increased awareness of the importance of protecting ourwater many cities are taking better steps to inform people when their annualtest is due.
3) What is a Backflow preventer? a. A Backflowpreventer is a means of mechanism to prevent Backflow. The basic means ofpreventing Backflow is an air gap, which either eliminated a cross-connectionor provides a barrier to Backflow. The basic mechanism for preventing Backflowis a mechanical Backflow preventer, which provides a physical barrier toBackflow. The principal types of mechanical Backflow preventers are thereduced-pressure principle assembly, the pressure vacuum breaker assembly, andthe double check valve assembly. A secondary type of mechanical Backflowpreventer is the residential dual check valve.
4) What is a reduced principle (RP) assembly? a. An RP is amechanical Backflow preventer that consists of two independently acting,spring-loaded check valves with a hydraulically operating, mechanicallyindependent, spring-loaded pressure differential relief valve between the checkvalves and below the first check valve. It includes shutoff valves at each endof the assembly and is equipped with test cocks. An RP is effective againstback pressure and backsiphonageand may be used to isolate healthor non-health hazards.
5)What is Backsiphonage? a. Backsiphonageis a condition that causes a sub-atmospheric pressure to be applied to theupstream side of the assembly. Backsiphonage can happen for several reasons;one of the more common is excessive water demand in the distribution system.
6) What is an air gap? a. An air gap is a vertical, physical separation between theend of a water supply outlet and the flood-level rim of a receiving vessel.This separation must be at least twice the diameter of the water supply outletand never less than one inch. An air gap is considered the maximum protectionavailable against back pressure Backflow or backsiphonage, but is not alwayspractical and can be easily bypassed
7) What is a double check valve assembly? a. A DCVA is a mechanical Backflow preventer that consists oftwo independently acting, spring-loaded check valves. It includes shutoffvalves at each end of the assembly and is equipped with test cocks. A DC iseffective against back pressure Backflow and backsiphonage but should be usedto isolate only non- health hazards.
