Axial flow check valve

Product Overview

The Axial Nozzle Check Valve is a spring‑assisted check valve featuring a Venturi/nozzle‑type flow path, with a disc that moves axially along the direction of media flow. Its core design incorporates a nozzle/Venturi shape inside the body, which accelerates and decelerates the flow in a streamlined manner, significantly reducing turbulence and pressure loss. The disc closes rapidly under the combined action of spring force and reverse media pressure, completing closure before reverse flow occurs, thereby completely eliminating water hammer and slamming noise.

Compared with traditional check valves, the axial nozzle check valve offers extremely low flow resistance (pressure loss only 10%–20% that of swing check valves), faster closing speed, and virtually zero water hammer impact. This valve is widely used in applications with high demands on energy efficiency and water hammer protection, such as high‑pressure pump discharges, long‑distance water transmission lines, petrochemical plants, power stations, seawater desalination, and water treatment systems. The valve features flanged connections and is available in ductile iron, carbon steel, stainless steel, and other materials, with nominal diameters from DN50 to DN1200 and pressure ratings up to Class 2500.

Product Structure

The Axial Nozzle Check Valve mainly consists of the following parts:

1. Body: Cast or forged body with a Venturi/nozzle flow path, available in ductile iron (QT450‑10), carbon steel (WCB), stainless steel (CF8/CF8M), etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. The internal flow path first contracts and then expands, creating a nozzle effect.

2. Disc: Streamline disc or cylindrical disc that moves axially along the flow direction. The sealing face can be hardfaced with Stellite or covered with rubber/PTFE.

3. Spring: Stainless steel coil spring or disc spring providing initial closing force to maintain sealing at zero flow.

4. Guide Mechanism: Axial guide ribs or a guide sleeve inside the body ensure smooth axial movement of the disc without tilting or jamming.

5. Seat: Located at the nozzle throat or outlet side, either a metal seat (Stellite hardfaced) machined in the body or an inserted soft seat (PTFE, PEEK, NBR, EPDM).

6. Stop Device: Limits the maximum disc opening to prevent over‑travel.

7. Access Cover: Removable bonnet or end cover for internal part inspection and replacement.

Compact construction with a nozzle flow path that makes media flow smoother, resulting in extremely low pressure loss.

Function

1. Prevents Backflow: Forward flow pushes the disc axially open; reverse flow or flow stoppage makes the disc close rapidly under spring force and backpressure, stopping backflow.

2. Extremely Low Flow Resistance: The Venturi nozzle flow path eliminates abrupt flow changes and eddies. Pressure loss when fully open is only 10%–20% of that of traditional swing check valves, providing exceptionally high energy savings.

3. Non‑Slam Closing (Water Hammer Elimination): The disc closes before reverse flow occurs, with extremely fast closing speed, eliminating the slamming noise and water hammer pressure waves common in traditional check valves.

4. Rapid Response: The spring provides instantaneous closing force; combined with the axial straight‑stroke design, response time is in milliseconds, especially suitable for high‑pressure, high‑frequency start‑stop, or systems with rapidly changing flow velocity.

5. Zero Leakage Sealing: Soft sealing options provide bubble‑tight sealing; metal sealing also meets low leakage standards.

6. Low Opening Pressure: Optimized spring stiffness, opening pressure typically 0.003–0.015 MPa.

7. Flow Disturbance Resistance: The axially symmetric design makes the disc insensitive to flow disturbances, ensuring stable operation even under pulsating flow.

Working Conditions

1. Applicable Media: Water, raw water, seawater, sewage, oil, chemical media, gas, steam, etc.

2. Temperature Range: –29°C to +200°C (soft seated); –29°C to +550°C (metal seated, material dependent).

3. Pressure Rating: Class 150, 300, 600, 900, 1500, 2500 (PN16 – PN420).

4. Nominal Diameter: DN50 – DN1200 (2″ – 48″); larger sizes available on request.

5. Installation Position: Horizontal pipeline (recommended); vertical (flow upward) also acceptable.

6. Typical Applications:

   1. High‑pressure centrifugal/plunger pump discharges (energy saving and water hammer protection)

   2. Long‑distance water transmission lines (reducing pumping energy consumption)

   3. Seawater desalination high‑pressure reverse osmosis inlets

   4. Petrochemical plant pump discharges

   5. Power plant boiler feedwater and cooling water systems

   6. Water hammer‑sensitive systems (e.g., high‑rise building water supply, precision instrument cooling)

   7. Compressor and gas pipelines (low flow resistance requirements)

Summary

The Axial Nozzle Check Valve, with its unique advantages of Venturi/nozzle low‑resistance flow path, spring‑assisted axial closing, millisecond rapid response, and zero water hammer impact, is the preferred anti‑backflow device for high‑pressure, high‑flow, and energy‑efficient piping systems. Its flow resistance is only 10%–20% of that of traditional swing check valves, significantly reducing pumping energy consumption.

At the same time, the disc closes before reverse flow occurs, completely eliminating water hammer hazards and protecting pipelines and equipment. This valve is especially suitable for applications sensitive to both energy efficiency and water hammer protection, such as long‑distance water transmission, high‑pressure pump discharges, seawater desalination, and petrochemical plants. For pipeline systems that pursue maximum energy savings, system safety, and smooth operation, the Axial Nozzle Check Valve is an ideal core component.