Description
The "RP" device, as it is commonly referred to, is a backflow prevention device which is used to prevent "backflow" of foreign liquids and other matter into the potable supply of water which could result in contamination. Backflow can occur when the pressure on our system is less then the pressure on a customer's system. For example, if a fire department were to draw too much water while fighting a fire, it would reduce the pressure in the area's water main below that which exists in, say an industrial building, thus back-siphoning chemical mixtures from the building into the water main. This could contaminate that area's water. While uncommon, pressure differentials can happen and protective devices must be used as required by law to protect the water supply.

The RP device, which actually prevents the backflow of water, stays open when water is flowing in one direction only. If a change of direction occurs, as it would during a major reduction in pressure, the RP device would close and prevent a contamination backflow.

Health Department Requirements
In addition to state regulations governing the requirements for backflow prevention devices, the Deparment of Public Health also requires that controls be in place for hazardous operations under private control in order to safeguard the water supply.

Fire-flow Requirements and Effects
RPZ devices, while very effective in protecting the water supply from backflows, can cause reductions in pressure and fire-flow capacity.

Fire-flow capacity is regulated by fire departments, fire marshals, fire underwriting agencies and other regulating agencies. Their requirements may affect the size and makeup of a project, the cost of fire and liability insurance, and ultimately your bottom line.

We realize that it is important to prevent backflows for health reasons and to maintain good fire protection.

Maintenance Responsibility
The operation and maintenance of water facility structures on private property are generally the proprietor's responsibility. This may include general maintenance of the structure, painting, street maintenance, repair of main breaks and interruptions of water service, related damages and insurance. Backup and administration to respond to any related emergency would also be required

 

Backflow Prevention Devices
  • Air gap
  • Atmospheric vacuum breaker (AVB)
  • Chemigation valve (primarily used in agriculture)
  • Check valve although not a legally approved method of backflow prevention.
  • Double check valve, or double check valve assembly (DCVA)
  • Pressure vacuum breaker assembly (PVB)
  • Reduced Pressure Principle Backflow Prevention Assembly (RP), RP Assembly, or RPZ (Reduced Pressure Zone)


    A double check valve or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination. It consists of two check valves assembled in series usually with a ball valve or gate valve installed at each end for isolation and testing. Often, test cocks (very small ball valves) are in place to attach test equipment for evaluating whether the double check assembly is still functional.

    The double check valve assembly is suitable for prevention of back pressure and back siphonage, but is not suitable for high hazard applications. It is commonly used on lawn irrigation, fire sprinkler and combi-boiler systems.