Backflow preventer

Descripción general del producto

The Copper Double Check Backflow Preventer is a compact anti‑backflow device featuring a high‑quality brass body and two independent check valves connected in series with no intermediate relief chamber. It is specifically designed to prevent low‑hazard, non‑health‑threatening media (such as slightly contaminated water, air conditioning water, industrial recirculating water, etc.) from flowing back into the upstream potable water supply. This device is a double check valve (DC) type, conforming to EN 1717 and ASSE 1015 standards, and is suitable for low‑risk (non‑toxic, non‑carcinogenic) backflow prevention applications.

Compared with reduced pressure zone (RPZ) backflow preventers that incorporate a relief chamber, this product offers extremely low flow resistance, no water discharge, no water waste, and simple installation. The body is forged or cast from brass (CW617N or HPb59‑1) with female threaded ends. Available in nominal diameters from DN15 to DN65, it is widely used in small to medium bore piping systems for residential and commercial buildings, air conditioning, boiler makeup water, landscape irrigation, and similar applications.

Product Structure

The Copper Double Check Backflow Preventer mainly consists of the following parts:

1. Body: Forged or precision cast brass (CW617N, HPb59‑1, or DZR dezincification‑resistant brass). Female threaded ends (NPT, BSPT, BSPP, or G threads).

2. First Check Valve (upstream): Spring‑loaded lift type check valve with a rubber soft seal (NBR/EPDM).

3. Second Check Valve (downstream): Same construction as the first, installed in series within the body to provide dual sealing redundancy.

4. Spring Assembly: Stainless steel (304/316) coil springs providing initial closing force and rapid response.

5. Test Cocks (optional): Test ports located in the chamber between the two check valves (brass or stainless steel) for field verification of each check valve’s sealing performance.

6. Bonnet: Removable brass bonnet for easy maintenance and cleaning of internal cartridges.

All internal parts can be accessed from the bonnet side. With no intermediate relief chamber, the flow path is simple and pressure loss is minimal.

Function

1. Prevents Backpressure Backflow: When downstream pressure exceeds upstream pressure, both check valves close simultaneously, using spring force and reverse pressure to create a dual seal, stopping backflow.

2. Prevents Backsiphonage: When upstream pressure drops sharply to a negative condition, both check valves close quickly, cutting off any siphon backflow from downstream media.

3. Low Resistance Operation: With no intermediate relief chamber, the flow path is unobstructed, and pressure loss is typically ≤ 0.15 bar, making it suitable for continuous flow systems with significant energy savings.

4. Redundant Sealing Protection: Two independent check valves provide fail‑safe protection – even if one disc is slightly blocked by debris or its seal ages and leaks, the other stage maintains sealing, preventing backflow.

5. No Water Discharge: Unlike RPZ types, this product does not discharge water during normal operation, resulting in no water waste and no need for drain piping.

6. In‑Line Testing: The sealing integrity of each check valve can be tested individually using the test cocks without removing the valve from the pipeline.

7. Any‑Angle Installation: Springs provide initial sealing force, allowing horizontal or vertical installation (vertical requires upward flow).

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Working Conditions

1. Applicable Media: Tap water, air conditioning cooling water, heating hot water, industrial recirculating water, swimming pool makeup water, irrigation water, fire protection water, lightly contaminated water (non‑fecal, non‑toxic chemicals).

2. Temperature Range: 0°C to +80°C (standard EPDM seals); –20°C to +120°C (FKM seals).

3. Clase de presión: PN10, PN16 (Class 125, Class 150).

4. Diámetro Nominal: DN15, DN20, DN25, DN32, DN40, DN50, DN65 (1/2″ – 2½”).

5. Installation Position: Horizontal (recommended) or vertical (flow upward).

6. Typical Applications:

   1. Residential and commercial building domestic water inlet pipes (preventing backflow from household to municipal mains)

   2. Air conditioning chilled water/cooling water makeup lines

   3. Small boiler and solar water heater makeup

   4. Landscape irrigation take‑off points

   5. Swimming pool and ornamental pond makeup water

   6. Fire protection system auxiliary water connections

   7. Non‑direct contact process makeup water in food plants

 Summary

The Copper Double Check Backflow Preventer, with its high‑quality brass corrosion‑resistant body, series dual check valve redundant design, extremely low flow resistance, no water discharge, and easy threaded installation, is a cost‑effective anti‑backflow solution for low‑health‑hazard (non‑toxic contamination) applications. Compared with reduced pressure zone (RPZ) types, it has no intermediate relief chamber, resulting in lower pressure loss, no water waste, and simpler installation – making it particularly suitable for continuous flow systems with strict pressure drop requirements in small to medium bore pipelines.

The product meets international and national backflow prevention standards and is widely used in residential, commercial, irrigation, and industrial makeup water systems. For pipeline systems that need to prevent non‑health‑hazard backflow while pursuing low operating costs, the Copper Double Check Backflow Preventer is an ideal core protection device.