Backflow preventer

Product Overview

The Threaded Low Resistance Backflow Preventer is a compact anti‑backflow device consisting of 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.

Compared with reduced pressure zone (RPZ) backflow preventers that incorporate a relief chamber, this product offers extremely low flow resistance (typically ≤ 0.15 bar pressure loss at full open), no water discharge, no water waste, and simpler installation. The valve features a high‑quality brass or stainless steel body with female threaded ends, conforming to EN 1717 (DC type) and ASSE 1015 standards. It is widely used in low‑risk backflow prevention applications such as residential buildings, commercial air conditioning, boiler makeup water, and landscape irrigation, with nominal diameters from DN15 to DN65.

Produktstruktur

The Threaded Low Resistance Backflow Preventer mainly consists of the following parts:

1. Gehäuse: Forged or precision cast body in brass (CW617N) or stainless steel (CF8/304). Female threaded ends (NPT, BSPT, BSPP, or G threads).

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

3. Second Check Valve (downstream): Same construction as the first, installed in series 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 for field verification of each check valve’s sealing performance.

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

Compact overall length, light weight, no relief chamber, optimized flow path for minimal pressure loss.

Funktion

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 (spring‑assisted type): Springs provide initial sealing force, allowing horizontal or vertical installation.

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Arbeitsbedingungen

1. Anwendbare Medien: 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. Temperaturbereich: 0°C to +80°C (standard EPDM seals); –20°C to +120°C (FKM seals).

3. Druckstufe: PN10, PN16 (Class 125, Class 150).

4. Nenndurchmesser: DN15 – DN65 (1/2″ – 2½”).

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

6. Typische Anwendungen:

   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

Zusammenfassung

The Threaded Low Resistance Backflow Preventer, with its advantages of 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.

The product is available in high‑quality brass or stainless steel bodies, offers strong corrosion resistance, and can be installed horizontally or vertically. Widely used in residential, commercial, irrigation, and industrial makeup water systems, the Threaded Low Resistance Backflow Preventer is an ideal core protection device for pipeline systems that need to prevent non‑health‑hazard backflow while pursuing low operating costs.