Double check backflow preventer

Backflow preventer is mainly used to prevent the medium in the pipeline from backflow due to pressure inversion, applicable to water, air and non-corrosive liquids, widely used in municipal water supply, building water supply and drainage, fire-fighting and industrial circulation system. Working temperature is generally 0 ℃ to 80 ℃, special materials can withstand higher temperatures. It is suitable for normal pressure to low and medium pressure working conditions. The main function is to realize double protection through the internal non-return and pressure relief structure to prevent backflow of contaminated media. Commonly used materials include copper alloy, stainless steel and ductile iron, compact structure, easy maintenance, to protect the system water quality safety and operational stability.

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products

Double check backflow preventer

Model: DH41X / HS41X

Subtitle: Two-stage backflow preventer/fouling isolation valve

Double check backflow preventer is an efficient equipment to prevent fluid backflow, widely used in drinking water, fire-fighting systems, industrial pipelines and sewage treatment and other fields. The device is mainly used to prevent backflow of water in the water supply pipeline, to avoid contamination of the water source or harmful substances in the system backflow back to the water supply network, to ensure the safety of water quality....

Classification:backflow preventer

Working conditions:waterwork, water treatment plant

Product Overview

Double check backflow preventer is an efficient equipment to prevent fluid backflow, widely used in drinking water, fire fighting system, industrial pipeline and sewage treatment and other fields. The equipment is mainly used to prevent backflow of water in water supply pipelines, to avoid contamination of water sources or harmful substances in the system backflow back to the water supply network, to ensure the safety of water quality. It is suitable for piping systems of water, sewage, oil and slightly corrosive liquids.

The Double Check Backflow Preventer doubly protects the piping system by means of two independent check valve assemblies. Once backflow is detected, the two check valves will automatically close, effectively preventing backflow from occurring. Product advantages include compact structure, superior sealing performance, sensitive response, low flow resistance, and is suitable for a variety of water quality environments. The equipment is made of corrosion-resistant materials to ensure that it maintains efficient performance in long-term use. The main function of the double check backflow preventer is to safeguard the safety of the water source and piping system, and to prevent pollution sources from entering the water supply system. Widely used in the need to prevent backflow and water quality protection occasions, is to ensure that the water supply system healthy and reliable operation of the ideal equipment.

Main characteristics

Dual check valve design: First check valve: prevents backflow under atmospheric conditions. Second check valve: acts as a backup barrier in case of failure of the first check valve. Pressure relief chamber (optional): automatically relieves intermediate pressure to prevent contamination.

Low resistance to flow: optimized flow path minimizes pressure drop (Cv ≥ 1.2 at DN50). Ideal for high-flow systems requiring energy savings.

Durable materials: Bronze (C83600): lightweight and corrosion-resistant for general use. Stainless Steel (304/316L): Excellent resistance to chlorides and acids. Ductile Iron (EN-GJS-400-18): Heavy duty construction for industrial applications.

Compliance and Safety: Complies with ASSE 1015, EN 1717 and ISO 5208. Leakage class VI (zero leakage under test conditions).

Ease of Maintenance: Modular design allows for quick inspection and seal replacement. Test plugs that can be field tested without disassembly.

Product Advantages

Fail-safe: Dual check valves provide redundant protection against backflow.

Energy saving: low pressure drop, reducing the load on the pump.

Versatile: Suitable for water, air and non-corrosive fluids.

Compliance Ready: Pre-certified for global regulatory requirements.

Comparison of similar products

hallmark	backflow preventer	General check valve
reflow protection	Redundancy (two check valves)	single barrier
security level	High (in accordance with ASSE 1015/EN 1717)	Basic (generic)
appliance	Critical systems (potable water, fire protection)	Non-critical systems
(manufacturing, production etc) costs	Higher initial cost	Lower initial costs

Medium of use

Water/hot water

working condition

waterwork, water treatment plant

summarize

Double check valve backflow preventers are essential for safeguarding water quality in drinking water and industrial systems. Its double valve design, compliance with strict standards and durable construction ensure reliable backflow prevention in high-risk environments. Whether used in municipal water networks, fire protection or industrial processes, this valve offers unrivaled safety and performance.

Product Parameters

Nominal diameter	DN50 to DN300 (2" to 12")
Nominal pressure	PN10 to PN25 (EN 1092) / Class 150 to 300 (ASME B16.34)
Applicable temperature	-20°C to 120°C (EPDM seals)
Valve Material	Bronze (C83600), 304/316L stainless steel, ductile iron (EN-GJS-400-18)
sealing material	EPDM, NBR, or PTFE (FDA-compliant options available)
connection method	Flanges (EN 1092/ASME B16.5)