Backflow Preventers

Backflow is the undesirable reversal in the flow of water from a real or potential source of contamination back to the potable (or clean) water supply. Consider having a garden hose in a bucket of soapy water at your home, and having backflow event occur causing that soapy water to "backflow" into the drinking water portion of your home. Various types of backflow preventers exist for different applications and health hazard conditions, check state and other local administrative codes or other regulation on the correct backflow to use. The most common are reduced pressure backflow preventer and double backflow preventer valves. Backflow preventers are primarily used in sewer, wastewater, residential, sprinkler and irrigation backflow applications.

Backflow Prevention Devices | Sewer

The term "Cross-Connection Control" is essentially is referring to backflow prevention. The definition of a Cross Connection is "A cross connection is the actual or potential connection between a non-potable substance or source." Local authorities will dictate what types of backflow preventers may not be used depending on the backflow risk and health hazard. Sewer, irrigation, wastewater and residential are the main areas. There are two types of backflow, the first is back pressure where the pressure in the downstream piping is greater than the supply pressure, this is caused by a pump or elevation of water in a high rise building, the other type of backflow is back siphonage which is caused by sub-atmospheric pressure in the water system piping.

You must have a Sewer Backflow Prevention Device on your sewer system. In most places this is the law, everywhere else it’s just the smart thing to do. Almost everywhere the local authorities will dictate that certain types of backflow preventers may not be used with irrigation and sewer systems because they do not provide adequate protection. In some cases, the authorities will dictate the exact type of backflow preventer you MUST use.

Danfoss Flomatic manufactures:

• Backflow Preventers
• Backflow Prevention Devices
• Reduced Pressure Backflow Preventer
• Double Backflow Prevention Valves
• Sewer Backflow Prevention Devices
• Wastewater Backflow Prevention Devices
• Residential Backflow Prevention Devices

See below for more Backflow Preventer Valve variations

Air Gap Adapter Size(s): 1/2 to 8 in. (15 to 200 mm)

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	DCV Double Check Valve Assembly Size(s): 2 1/2 to 10 in. (65 to 250 mm)	View Details Submit RFQ
	DCVE Double Check Valve Assembly Size(s): 3/4 to 2 in. (20 to 50 mm)	View Details Submit RFQ

	RPZ Reduced Pressure Zone Assembly Size(s):2 1/2 to 10 in. (65 to 250 mm)	View Details Submit RFQ
	RPZE Reduced Pressure Zone Assembly Size(s): 3/4 to 2 in. (20 to 50 mm)	View Details Submit RFQ
	RPZE II Reduced Pressure Zone Assembly Size(s): 1/2 to 1 1/2 in. (15 to 40 mm)	View Details Submit RFQ
	RPZSS II Reduced Pressure Zone Assembly Size(s): 1/2 to 3/4 in. (15 to 20 mm)	View Details Submit RFQ
	RPZESA Reduced Pressure Zone Assembly Size(s): 3/4 to 2 in. (20 to 50 mm)	View Details Submit RFQ

PVB Pressure Vacuum Breaker Assembly Size(s): 3/4 to 2 in. (20 to 50 mm)

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Test Kit TK 1 This backflow prevention assembly test kit is designed for field testing of all brands of reduced pressure principle, double check and pressure vacuum breakers.

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SDC Single Detector Check Size(s): 4 - 6 in. (100 - 150 mm)

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AVB Atmosperic Vacuum Breaker Size(s): 1/2 to 2 in. (15 to 50 mm)

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CB20 Carbonated Beverage Backflow Preventer Size(s): 3/8 in. (10 mm)

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HB8 Hose Connection Vacuum Breakers Size(s): 3/4 in. (20 mm)

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	8080 Dual Check Valve Size(s): 3/4 to 1 in. (20 to 25 mm)	View Details Submit RFQ
	8080E Dual Check Valve Size(s): 1/2 to 1 in. (15 to 25 mm)	View Details Submit RFQ

8200 Dual Check Valve with Atmospheric Vent Size(s): 1/2 to 3/4 in. (15 to 20 mm)

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Backflow Prevention Devices | Wastewater | Residential

Various types of backflow preventers exist for different applications and health hazard conditions, check state and other local administrative codes or other regulation on the correct backflow to use. The following backflow preventer types are available in all sizes:

Reduced Pressure Backflow Preventer - Model RPZ, RPZE and RPZE II - The Reduced Pressure Principle Assembly (RP) is the best mechanical means of preventing backflow pressure and back siphonage. These are made for non-health hazard or high-hazard conditions and are designed to protect against back siphonage or backpressure. These assemblies are the most expensive backflow prevention devises but are the best way to protect against cross connections while in operational conditions. The unit must be installed 12 inches (300 mm) above ground and no more than 30", check with local authorities. The RP assemblies may spit out water of relief port for a variety of reasons so they must have a floor drain if being installed inside a building. Some of the reasons for spitting or flow from relief valve ports are if they detect backflow, inlet/outlet pressure fluctuations, dirt, or debris on first check valve or relief valve. Check trouble-shooting guides. It is also recommended that a strainer be installed with a RP device due to the sensitivity of the check valves and relief valve ports to dirt or debris.

Double Check Backflow Preventers - Model DCV, DCVE - The Double Check Valves are used in non-health hazard (pollutant) conditions only and are designed to protect against backflow pressure and back siphonage. They are basically a device with TWO check valves inline designed to prevent backflow. These units may be buried in valve boxes and do not have a relief valve port like the RP device. Check with local authorities for required installation heights and some do not allow the use of a DCV.

Dual Check Valve - Model 8008, 8080E - The Dual Check Valve or double backflow prevention valve is basically a stripped down Double Check Valve without shut off valves and test cocks. They are non-testable and are typically used by water companies and installed after a water meter to prevent the meter from running backwards and low protection against backflow. This piece of equipment is the center of controversy with many backflow authorities and should never be confused with Double Check Valves. Check with local authorities for required installation, as most do not recognize these as backflow prevention devices.

Atmospheric Vacuum Breaker - Model AVB - The atmospheric vacuum breaker is one of the least expensive backflow prevention assembly. The AVB is a non-testable unit and are good for back siphonage only for non-health hazard or health hazard conditions. They must be installed downstream from any shut off valves and cannot be under pressure for more than 12 hours. If an AVB is used backflow prevention on a irrigation system you must install one AVB after every valve for each zone in the system. It must also be installed at least 6 inches (150 mm) higher than the highest outlet in the system (some AVB manufacturers, and some local officials, require that they be installed 12 inches (300 mm) higher than the highest outlet). Some municipalities do not allow the use of AVB’s. These units will NOT prevent backflow pressure and can only protect against back siphonage.

Pressure Vacuum Breaker - Model PVB - A pressure vacuum breaker is similar to a Atmospheric Vacuum Breaker but can be installed before the shut off valves thus allowing you to install only one of them in a system. It must also be installed above ground and it must be 12 inches (304 mm) higher than the highest outlet in system. Check with local authorities for required installation heights and some do not allow the use of a PVB at all. A PVB backflow preventer may spill or spit water out from under the cap, so it should always be installed in a location where water spillage is ok. These units will NOT prevent backflow pressure and only protect against back siphonage.