Methods Used to Prevent Backflow 2
There are several backflow control methods that may be used for comparable degree of hazards. For example, an air gap or reduced pressure principle assembly or pressure vacuum breaker assembly can be used for high heal hazard cross-connections situations, since they are all approved for such installations. The pressure vacuum breaker can only be used for indirect cross-connections — backflow backsiphonage control.
Therefore, when choosing a backflow control method, the best use of the method should be considered. There is no best backflow control method. There is only the backflow control method that works best for controlling that particular cross-connection. When choosing the backflow control method, additional factors should be taken into consideration, such as but not limited to the following:
- interruption in piping system creating a loss of pressure
- regulatory and code requirements
- creation of a cross-connection incident
- temperature both water and air
- inlet and outlet piping size
- location of backflow control method
- characteristics of the downstream water quality or chemical makeup
- characteristics of the water supply – pressure, velocity, quality and quantity
- drainage issues
- servicing requirements
- tolerance and installation requirements
- hydraulics such as thermal expansion and water hammer
- fluctuating water supply pressure
- safety requirements
- regulatory and code requirements
- mechanical or non-mechanical method
- cost or expense
- manufacture and industry requirements or standards
- and the need to periodically inspect and test to ensure proper operation and protection
There are several manufacturers of devices and assemblies and they strive to design the devices and assemblies to meet the established standards for operation. Devices/assemblies, with the exception of the barometric loop, are manufactured to meet basic industry standards and they come in a variety of shapes and sizes. The device or assembly functions the same no matter what size or shape. All backflow methods shall comply with the industry standards to be approved.
The American Society of Sanitary Engineers (ASSE) has standards for both devices and device assemblies. The American Water Works Association (AWWA) has standards for the double check valve assembly and the reduced pressure principle assembly only. The University of California Foundation for Cross-Connection Control and Hydraulic Research (FCCCHR) has standards for all of the testable device assemblies and publishes a list comprised of backflow prevention assemblies, which have successfully completed a laboratory and field evaluation. Backflow prevention devices and device assemblies installed to prevent backflow shall meet these standards to be approved for use. Device/assemblies not approved by one or more of the industry recognized organizations shall not be used for cross-connection control.
State regulatory authorities will specify in the rules, regulation, or policies that backflow prevention device assemblies are approved for use by one or more of the above-mentioned industry recognized organizations.
The Reduction of Lead in Drinking Water Act was enacted on January 4, 2011 to amend Section 1417 of the Safe Drinking Water Act (SDWA or Act) respecting the use and introduction into commerce of lead pipes, plumbing fittings or fixtures, solder and flux. The Act established a prospective effective date of January 4, 2014. Exemptions to Section 1417 are pipes, pipe fittings, plumbing fittings or fixtures, including backflow preventers, that are used exclusively for non-potable services such as manufacturing, industrial processing, irrigation, outdoor watering, or any other uses where the water is not anticipated to be used for human consumption (SDWA 1417(a)(4)(A). Backflow preventers installed for hydraulic purposes on service lines for service line protection shall be lead free. Backflow preventers installed for cross-connection control do not have to be lead free.