Butterfly Check Valve

Product Overview

The Hydraulically Controlled Slow Closing Check Valve is a multi‑function check valve that actively controls the opening and closing process of the disc via a hydraulic system. Unlike ordinary check valves that close passively by media force, this valve uses an external hydraulic power unit or hydraulic cylinder to execute opening and closing actions according to a preset time program, achieving multi‑stage control such as “fast open – slow open – fast close – slow close” to precisely eliminate water hammer.

It is widely used in large pump discharges, long‑distance water transmission projects, high‑lift pumping stations, nuclear and thermal power plants, municipal water supply, and other applications with extremely high water hammer protection requirements. The valve features flanged connections, with body materials of carbon steel, ductile iron, or stainless steel, and nominal diameters up to DN2000 and above.

Product Structure

The Hydraulically Controlled Slow Closing Check Valve mainly consists of the following parts:

1. Body: Cast or fabricated body in carbon steel (WCB), ductile iron (QT450‑10), stainless steel (CF8/CF8M), etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc.

2. Disc (Butterfly/Swing Disc): Streamlined design, available in butterfly or swing type. The sealing face can be hardfaced or covered with rubber/PTFE.

3. Shaft: Stainless steel or corrosion‑resistant alloy heavy‑duty shaft supporting disc rotation.

4. Seat: Metal seat (Stellite hardfaced) or soft seat (rubber/PTFE); bidirectional sealing optional.

5. Hydraulic Actuator: Includes hydraulic cylinder, piston rod, rocker arm, or linkage. The cylinder is typically single‑acting or double‑acting to open and close the disc.

6. Hydraulic Power Unit (external or integrated): Includes oil pump, motor, tank, solenoid valves, pressure control valves, accumulator, etc., providing power and control signals to the cylinder.

7. Electrical Control System: PLC or relay control cabinet that receives pump start/stop signals and controls solenoid valves according to preset programs for automatic operation.

8. Position Indicator & Limit Switches: Provide valve position feedback and set switching points for fast close, slow close, full open, and full closed positions.

9. Accumulator (optional): Provides backup pressure in case of power failure or hydraulic system malfunction, enabling fail‑safe closing.

Robust structure with independent hydraulic system and high control accuracy.

Function

1. Prevents Backflow: Regardless of pump operating status, the hydraulic system ensures the disc is fully closed when the pump stops, stopping backflow.

2. Water Hammer Elimination (Multi‑Stage Closing): The closing process is divided into “fast close” and “slow close” stages:

   1. Fast close stage (approx. 70%–80% of stroke): Quickly stops most of the reverse flow, preventing pump reverse rotation.

   2. Slow close stage (remaining stroke): Closes slowly, smoothly dissipating water hammer pressure waves.

3. Controlled Opening Program: The opening process can also be divided into “fast open” and “slow open” to avoid sudden pressure drop during pump start‑up, protecting the pipeline.

4. Pump Interlock Control: Receives pump start/stop signals and automatically executes the program without manual intervention.

5. Fail‑Safe Protection: In case of power failure or hydraulic malfunction, the accumulator provides one or more closing actions to ensure safe valve closure.

6. Position Adjustment: Can maintain any opening degree during operation (throttling function) for flow or pressure regulation.

7. Remote Monitoring: Can be connected to a SCADA system for real‑time feedback of valve position, oil pressure, fault alarms, etc.

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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 (soft seated); –29°C to +425°C (metal seated, material dependent).

3. Pressure Rating: PN6, PN10, PN16, PN25, PN40, PN64 (Class 150, 300, 400, 600).

4. Installation Position: Horizontal pipeline (recommended); vertical installation requires customization.

5. Typical Applications:

   1. Large municipal water supply pump stations (long‑distance transmission)

   2. High‑lift pumping stations (mine drainage, water diversion projects)

   3. Thermal power plant circulating water pump discharges

   4. Nuclear power plant cooling water pump discharges

   5. Petrochemical plant large pump discharges

   6. Water conservancy and water transfer projects

   7. Large wastewater treatment plant lift pump discharges

Summary

The Hydraulically Controlled Slow Closing Check Valve, with its advanced features of hydraulic active control, multi‑stage opening/closing program, pump interlock, and fail‑safe protection, is the most reliable solution for water hammer protection in large, high‑lift, and long‑distance pumping stations. It not only precisely eliminates pump‑stop water hammer but also avoids sudden pressure drop during pump start‑up through a slow‑open function, comprehensively protecting the pump and pipeline system.

Compared with micro resistance slow closing check valves (passive type), the hydraulically controlled version offers higher control accuracy, wider applicability, and greater adaptability to complex operating conditions. For critical pumping stations with DN200 and above, high head, or long pipelines, the Hydraulically Controlled Slow Closing Check Valve is the core equipment ensuring system safety, and an ideal choice for automated pump station management.