Backflow Preventers(Low Pressure)

Backflow Preventers(Low Pressure)

Basic information
Basic information
This valve can strictly prevent the occurrence of backflow pollution, is a safe device to ensure the hygiene of drinking water. 
Features
Features
1. More superior streamline design, energy - saving effect;
2. Discharge control device and outlet are designed without obstacles to reduce fluid resistance;
3. More sensitive check effect, low opening pressure;
4. The top is provided with a lifting ring for easy installation.
Principle
Principle
When the inlet pressure is lower than the outlet pressure, the valve closes and the drain valve opens automatically, and it is always in the open state. The middle chamber is the same as the atmosphere, realizing air partition, and the partition performance is safe and reliable. When the water supply stops, the sealing force of the first and second check valve disc will increase automatically, effectively improving the sealing reliability. 
Installation and Commissioning
Installation and Commissioning
Butterfly or gate valves should be installed on both sides of the low resistance backflow preventer. Filters should be installed at the inlet and expansion or soft joint should be installed at the outlet. The discharge outlet of the drainer shall be additionally installed with the outlet pipe, which shall be downward directed to a place greater than or equal to 100mm above the intake port of the collector well. No valves shall be allowed in the middle. For specific use, please consult ZhengFeng Valve Group.

Part

Material

Standard

Body

Ductile Iron

EN 1563/DIN 1693

Bonnet

Ductile Iron

EN 1563/DIN 1693

Stem

Stainless Steel 431

EN10088-1/ASTM A959

Seat

Stainless Steel 431

EN10088-1/ASTM A959

Diaphragm

EPDM / NBR

ISO 4633

Disc

Stainless Steel 431

EN10088-1/ASTM A959

For the materials options not listed, consult factory.

ZhengFeng manufactures valves in more than 50 different alloys.

Product scope, Standards & Materials
Size Range: 2"~12"
Pressure Rating: 10bar ~ 25bar
Face to Face Dimensions: AMSE B16.10, EN558-1
Flange End Dimension: AMSE B16.1/16.42, AS4087, EN1092-2
Coating: Fusion Bonded Epoxy Coating
Inspection and Test: ISO 5208 / EN 12226-2

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