蝶式止回阀, 水用止回阀

Product Overview

The Micro Resistance Slow Closing Check Valve is an energy‑saving check valve specifically designed for pump discharge applications, featuring a slow‑closing function. It combines the low flow resistance characteristics of a swing check valve with a hydraulic damping device. During forward flow, the disc opens to a large angle with minimal resistance; when the pump stops or backflow occurs, the disc first closes rapidly for most of its travel, then closes slowly for the remaining travel, thereby greatly reducing water hammer pressure peaks and protecting the pump and pipeline system. This valve is widely used in municipal water supply, industrial recirculating water, high‑rise building water supply, fire protection systems, and agricultural irrigation where water hammer protection is required. The valve features flanged connections and is available in ductile iron, carbon steel, or stainless steel, covering sizes from DN50 to DN1200 and larger.

Product Structure

The Micro Resistance Slow Closing Check Valve mainly consists of the following parts:

1. Body: Cast or fabricated body 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.

2. Disc: Streamlined swing disc rotating around a top or eccentric pin shaft; single‑disc or dual‑disc design available. The sealing face can be rubber‑covered or hardfaced.

3. Pin Shaft: Stainless steel or corrosion‑resistant alloy pin shaft ensuring smooth disc movement.

4. Seat: Machined metal seat or inserted soft seat (rubber/PTFE) in the body.

5. Slow Closing Device (core component): Typically a hydraulic damping cylinder or piston‑type damper mounted externally on the body, connected to the disc shaft via a linkage. The device is filled with hydraulic oil and allows adjustable closing time.

6. Control Valve / Needle Valve: Located in the oil circuit of the slow closing device, used to set the slow closing speed (typically adjustable from 2 to 60 seconds).

7. Micro Resistance Mechanism: Double‑offset or streamlined disc design; when fully open, the disc lies flat along the flow path, providing an extremely low resistance coefficient.

Compact structure with independently adjustable slow closing device for easy maintenance.

Function

1. Prevents Backflow: Forward flow automatically opens the disc; pump stop or reverse flow makes the disc close under gravity, backpressure, and the slow closing device, stopping backflow.

2. Water Hammer Elimination (Slow Closing Function): Disc closing is divided into two stages – a fast‑close stage (approx. 80%–90% of travel) quickly stops most of the reverse flow, preventing severe water hammer; a slow‑close stage (remaining travel) smoothly dissipates residual water hammer energy.

3. Micro Resistance / Energy Saving: When fully open, disc resistance is minimal, with pressure loss typically below 0.02 MPa, significantly reducing pumping energy consumption.

4. Adjustable Slow Closing Time: By adjusting the needle valve, the optimal slow closing time (generally 3–60 seconds) can be set according to pipeline length, flow rate, head, etc.

5. Low Noise Operation: The slow closing function avoids the slamming noise typical of traditional check valves.

6. In‑Line Maintenance: The slow closing device can be independently removed and serviced without taking the valve off the pipeline.

Working Conditions

1. Applicable Media: Clean water, raw water, seawater, sewage, cooling water, oil, mildly corrosive liquids, etc.

2. Temperature Range: 0°C to +80°C (standard EPDM seals); high‑temperature version up to +120°C (FKM) or higher (metal seated).

3. Pressure Rating: PN10, PN16, PN25, PN40 (Class 150, Class 300).

4. Installation Position: Horizontal pipeline (recommended); vertical (flow upward) also acceptable if the slow closing device functions properly.

5. Typical Applications:

   1. Municipal water supply pump station discharges

   2. High‑rise building secondary water supply systems

   3. Industrial recirculating cooling water pump discharges

   4. Fire protection pump discharges

   5. Agricultural irrigation pumping stations

   6. Wastewater treatment plant lift pump discharges

   7. Heating station makeup water systems

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Summary

The Micro Resistance Slow Closing Check Valve, with its unique advantages of low flow resistance for energy saving, two‑stage slow closing for water hammer elimination, and adjustable slow closing time, is an ideal device for preventing water hammer and backflow at pump discharges. It solves the severe water hammer problem of ordinary check valves while being more economical and reliable than dedicated water hammer arresters. By properly setting the slow closing time, the valve can be perfectly matched to the pressure fluctuation characteristics of different pipelines, ensuring safe operation of pumps and piping systems. Whether in municipal pump stations, high‑rise water supply, or industrial recirculating systems, the Micro Resistance Slow Closing Check Valve provides smooth, quiet, long‑lasting anti‑backflow protection with low energy consumption. For pump discharge pipelines that demand system safety and operational efficiency, the Micro Resistance Slow Closing Check Valve is an indispensable key component.