防倒流装置

Product Overview

The Integral Stainless Steel Threaded Low Resistance Backflow Preventer is a compact anti‑backflow device featuring an all‑stainless‑steel one‑piece body with two built‑in check valve cartridges (no intermediate relief chamber). It is specifically designed to prevent low‑hazard, non‑health‑threatening media from flowing back into upstream potable water supplies. Unlike split‑body designs or traditional backflow preventers with test cocks, this product uses an integral one‑piece valve body with no external test ports or removable bonnet, resulting in a more compact structure, fewer sealing points, and lower leak risk.

The device offers extremely low flow resistance (≤ 0.15 bar pressure loss at full open), no water discharge, and no water waste. It has female threaded ends for easy installation. The all‑stainless‑steel construction (CF8/304 or CF8M/316) provides excellent corrosion resistance, high temperature capability, and a hygienic surface finish. Conforming to EN 1717 (DC type), it is especially suitable for corrosive media, high‑purity water, food, and pharmaceutical applications in small‑bore pipelines, with nominal diameters from DN15 to DN65.

Product Structure

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

1. Integral One‑Piece Body: Precision cast or forged stainless steel, material CF8 (304) or CF8M (316). One‑piece construction with no split connections, no bonnet, and no external test ports. Female threaded ends (NPT, BSPT, BSPP, or G threads).

2. First Check Valve Cartridge (upstream): Built‑in spring‑loaded check valve integrated inside the body, non‑removable.

3. Second Check Valve Cartridge (downstream): Installed in series with the first, integrated into the same body, providing dual sealing redundancy.

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

5. Seals: NBR, EPDM, FKM, or PTFE seals integrated inside the cartridges.

Structural Features:

1. No bolts, no bonnet, no test cocks

2. One‑piece forged or cast body with no external leak paths

3. Dual check valve cartridges pre‑assembled and non‑field‑serviceable

4. Short overall length, light weight, direct threaded connection to piping

Function

1. Prevents Backpressure Backflow: When downstream pressure exceeds upstream pressure, both built‑in check valve cartridges 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 cartridges 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.

4. Redundant Sealing Protection: Two independent check valve cartridges provide fail‑safe protection – even if one cartridge slightly leaks, the other stage maintains sealing, preventing backflow.

5. No Water Discharge: During normal operation, no water is discharged to the atmosphere, eliminating water waste and the need for drain piping.

6. Maintenance‑Free Design: The integral construction has no external serviceable parts, requiring no field adjustment or maintenance. At the end of service life, the entire unit is replaced.

7. Corrosion & High Temperature Resistance: The all‑stainless‑steel construction resists acids, alkalis, salts, seawater, chlorides, and many chemicals.

Working Conditions

Why stainless steel? In the following conditions, conventional brass backflow preventers would corrode, dezincify, or contaminate the media, making stainless steel mandatory. The integral design is particularly suitable for space‑limited installations where on‑site testing is not required.

1. Applicable Media:

   1. Corrosive media: dilute acids, dilute alkalis, salt solutions, seawater, chlorinated water, chemical solvents

   2. High‑purity water: deionized water, reverse osmosis permeate, water for injection (WFI), purified water

   3. Food & beverages: fruit juice, dairy products, syrup, beer, CIP cleaning fluids

   4. Pharmaceutical water: process water, rinse water

   5. High‑temperature water / steam condensate (above 80°C)

   6. Oils and chemicals (copper‑sensitive media)

2. Temperature Range: –20°C to +200°C (depending on seal material)

3. Pressure Rating: PN10, PN16, PN25 (Class 150, Class 300)

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

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

6. Typical Applications:

   1. Small‑bore corrosive media makeup lines in chemical plants

   2. Sampling and instrumentation lines in seawater desalination plants

   3. Point‑of‑use branches for purified water / WFI in pharmaceutical plants

   4. CIP cleaning branches in food & beverage production lines

   5. Deionized water makeup lines in electroplating plants

   6. Laboratory high‑purity water systems

   7. Boiler chemical dosing branch lines

   8. Instrument air and water sample lines

Summary

The Integral Stainless Steel Threaded Low Resistance Backflow Preventer, with its integral one‑piece body, all‑stainless‑steel corrosion‑resistant construction, series dual check valve cartridges, extremely low flow resistance, no water discharge, and maintenance‑free threaded installation, is the ideal anti‑backflow solution for small‑bore applications involving corrosive media, high‑purity water, and hygienic environments.

Compared with split‑body or test‑cock equipped alternatives, the integral design has no external leak paths, allows faster installation, and lowers maintenance costs – making it especially suitable for space‑limited installations where on‑site testing is not required or where sealing reliability is paramount. In chemical makeup lines, pharmaceutical purified water point‑of‑use branches, food CIP branches, and laboratory high‑purity water systems, the Integral Stainless Steel Threaded Low Resistance Backflow Preventer provides reliable, long‑lasting, maintenance‑free backflow protection.