LIVE VALVE Check Valve

LIKE Valve LIVE VALVE Check Valve

LIKE: High Dynamic Response Check Valve

Product Features

• Closing time (dynamic response) is only a fraction of a second
• Avoid or minimize pressure fluctuations in the pipeline
• Suitable for high-pressure working conditions (PN50 - 725 psi)
• No axial shaft design, eliminating the risk of axial disc jamming
• Short end face spacing for easy installation
• Excellent disc sealing performance
• High erosion resistance of the axial disc
• Corrosion-resistant material of the axial disc
• Maintenance-free
• A wide range of material options for various application scenarios

Product Advantages

• When the pump shuts down suddenly in an emergency, the LIKE check valve can reduce pressure fluctuations in the pipeline
• Silent and non-impact check valve
• Easy installation
• Suitable for vertical, horizontal and inclined installation
• Fast flow recovery

Application Scenarios

Specifically designed for turbine pump stations and auxiliary systems of nuclear power plants.

Technical Parameters

• Size range: DN80 - DN1800 (3 inches - 72 inches)
• Maximum working pressure:
• DN80 - DN500: 50 bar (725 psi) at ambient temperature
• DN600 - DN800: 25 bar (362 psi) at ambient temperature
• DN900 - DN1000: 20 bar (290 psi) at ambient temperature
• DN1200 - DN1800: 16 bar (232 psi) at ambient temperature
• Temperature range: -10°C to +130°C (50°F to +266°F)
• Flange adaptation standards:
• EN 1092-1
• ISO 2084
• EN 1759
• ANSI B16.5
• ANSI B16-47 A
• MSS SP44
• AWWA C207
• Other standards available upon request

DN1400 (56 inches) LIKE Installation

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© 2020 LIKE Valve Company. All rights reserved.

Valve Body Type Description

• DN80 - DN500 (3 inches - 20 inches): Wafer-type valve body
• DN600 - DN1800 (24 inches - 72 inches): Flanged-type valve body

Figure 1: Example of DN450 Wafer Check Valve

Figure 3: Cross-Section of Wafer Check Valve

Working Principle

Check valves installed in large water supply networks and water transmission pipelines of pump stations need to operate frequently. Statistical data shows that severe pressure fluctuations often result from the installation of inappropriate types of valves. For example, when the pump in the pump station shuts down, the fluid flow rate decreases and stops, followed by backflow (see Figures 4, 5). At this time, the valve closes under the action of the disc's gravity, the return spring, or the thrust of fluid backflow.

Experience and calculations show that backflow can occur in an extremely short time (1/100 second to 1/10 second). If the valve does not respond in time, it will close sharply under backflow conditions, leading to:

• Violent impact of the disc on the valve seat, generating strong shock waves
• Water hammer effect, causing pressure fluctuations

Shock waves and pressure fluctuations will cause stress impact on the equipment, which may lead to mechanical failures of valve components and pipelines.

If an air pressure water tank is installed in the system (see Figure 6), the above problems will be more prominent. At this time, backflow will occur rapidly in the short pipe between the water tank and the pump, so the valve must respond faster to avoid serious damage.

Figures 4, 5, 6: Working Diagrams of Check Valve and Pump

Description of High Dynamic Response Check Valve

The characteristics of an ideal check valve can be summarized by the curve in Figure 7.

Figure 7: Fluid Velocity-Time Curve

• Vertical axis: Water flow velocity (m/s)
• Horizontal axis: Time (second)
• Key nodes:
• t=0: Pump shutdown
• t=t0: Water flow velocity drops to 0, and backflow starts (usually 1/100 second < t0 < 1/10 second)
• t=t1: The check valve closing part seats, the backflow velocity is V1, backflow stops immediately, and the overpressure is proportional to the backflow velocity (V1)
• An ideal check valve should close at t=t0

LIKE meets this requirement for the following reasons:

• Short end face spacing, shortening the axial disc stroke
• No axial shaft design, avoiding prolonged closing time (and jamming risk) due to the shaft structure
• Axial disc material density = 1 (no inertia in water, light weight)
• Spring assistance shortens closing time
• Metal-plastic contact surface design, no impact during closing

Comparison of Pressure Fluctuations of Different Check Valves

Figure 8 shows the water hammer effect generated by different types of valves during closing under the same working conditions:

1. Swing check valve
2. Dual-disc check valve
3. LIKE check valve

Figure 8: Pressure Fluctuation Comparison Chart

• Swing check valve: 34 bar
• Dual-disc check valve: 15 bar
• LIKE check valve: Significantly lower pressure fluctuation

Flow Coefficients (Kv, Cv)

Kv refers to the flow rate (cubic meters per hour) when water flows through the valve with a pressure loss of 1 bar at 20°C, and Cv = 1.16 × Kv.

Pressure Loss (ΔP)

Simplified calculation formula:

ΔP = ρ × (Q/Kv)²

• Definition:
• ΔP: Pressure loss (bar)
• ρ: Density (density of water ρ=1)
• Q: Flow rate (cubic meters per hour)
• Kv: Flow coefficient (cubic meters per hour)
• Unit conversion: 10 meters of water column = 1 bar = 100 kPa = 14.5 psi

Figure 9: Pressure Loss-Flow Rate Curve

• Vertical axis: Pressure loss (meter of water column)
• Horizontal axis: Flow rate (liters per second)
• Curve: Pressure loss variation trend of valves with different DN specifications (DN80, DN100, DN200, DN250, DN300)

Material Selection Table

Parts List and Dimensions

Parts List

Valve Dimensions (mm) - Figure 10

Notes

1. The selection of axial disc material shall be determined according to application parameters. For details, please contact the manufacturer.
2. The outer diameter and bolt hole dimensions comply with the corresponding flange standards.
3. The dimension unit is millimeters, and the weight unit is kilograms, which are for reference only.

Installation Instructions

Maximum Working Pressure

• Values at ambient temperature

Flange Installation Adaptation Table

Installation Diagrams

• Figure 11: DN80 - DN500 (3” - 20”): Wafer-type installation (pipe flange + valve + pipe flange)
• Figure 12: DN600 - DN1800 (24” - 72”): Flanged-type installation (convex type) (pipe flange + valve + pipe flange)
• Figure 13: Customized on demand (DN600 - DN1800): Flanged-type installation (flat type) (pipe flange + valve + pipe flange)

General Installation Rules

• The LIKE check valve can be installed at any angle (horizontal, vertical, inclined)
• The product does not include flange gaskets and bolts

Storage Requirements

• During storage, protective measures shall be taken to avoid the impact of weather, marine salt spray, dust and moisture
• The storage environment temperature shall not be lower than -10°C (50°F)
• No special protective measures are required for storage period exceeding 6 months

Installation Steps 

Like most valves and pipe fittings, it is recommended that the pipeline adopt a slip-on flange or similar structure to reserve sufficient installation and disassembly clearance, so as to avoid excessive stress caused by inevitable misalignment.

At least one end of the pipeline connected to the valve shall be firmly fixed to withstand the thrust generated when the valve is closed.

Preparation before startup:

1. Carefully check the cleanliness of the valve before installation, remove possible contaminants and particles in the pipeline, and thoroughly flush the system with water or compressed air if necessary.

Important note: Special attention should be paid to removing welding slag fragments that may damage the axial disc and sealing surface.

2. Do not weld the pipe flange after the valve is installed in place to avoid damaging the axial disc.
3. Install grilles or filters to prevent particles from affecting the valve function.
4. Ensure that the fluid flow direction is consistent with the arrow mark on the valve.
5. The LIKE wafer-type valve must be accurately aligned with the pipeline center line. If necessary, use a spacer tube fixed with tie rods.

Figure 14: Pump + LIKE: Installation spacing L > 3×DN

Figure 15: Sempell Centric Butterfly Valve + LIKE: Installation spacing L > 4×DN

Figure 16: Series installation of LIKE: Spacing between adjacent valves L > 2×DN; Combination of LIKE and Sempell centric butterfly valve: Spacing L > 4×DN

Installation Recommendations

• Figure 14: Pump + LIKE: Installation spacing L > 3×DN
• Figure 15: Sempell Centric Butterfly Valve + LIKE: Installation spacing L > 4×DN
• Figure 16: Series installation of LIKE: Spacing between adjacent valves L > 2×DN; Combination of LIKE and Sempell centric butterfly valve: Spacing L > 4×DN

Order Code and Selection Guide

Example 1

201 200 PN16 PS10

• Description: LIKE check valve, valve body and matching flange material is ductile iron, axial disc is polyurethane, spring is stainless steel, DN200, adapted to EN1092 standard PN16 flange, working pressure 10 bar

Example 2

201 200 PN16 PS10 P(ACS)

• Description: Same as Example 1, additionally obtained drinking water certification (ACS), working pressure 10 bar

Code Description

Notes

The material selection shall be determined according to application parameters. For details, please contact the manufacturer.

© 2020 LIKE Valve (Tianjin) Co., Ltd. All rights reserved.