Manual control valves are control components in pipeline fluid transport systems. They are used to change the cross-sectional area of the passage and the direction of medium flow, and have functions such as guiding, shutting off, regulating, throttling, checking back, diverting, or overflowing and relieving pressure.
Valves used for fluid control range from the simplest shut-off valves to various valves used in extremely complex automatic control systems. They come in a wide variety of types and specifications, with nominal diameters ranging from extremely small instrument valves to industrial pipeline valves with diameters up to 10m.
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Manual control valve Performance Advantages:
1. Improved Heating Supply: Branch lines and heating points using manual regulating valves can adjust flow according to design conditions to achieve optimal temperature operation. These valves offer better regulation than gate valves and globe valves, exhibiting near-linear regulation performance. Therefore, uneven heating in various buildings is significantly reduced.
2. Energy Saving: Temperature and pressure imbalances in the heating network can cause excessive flow in some branches, leading to overheating in some buildings and forcing residents to open windows, thus saving energy.
3. Improved Hydraulic Conditions: Manual regulating valves control flow according to rated flow, reducing excessive flow in the network and improving the original deterioration of hydraulic conditions.
Manual control valve Basic Principles
Manual regulating valves change the flow area by rotating or pulling the valve stem, which moves the valve core within the valve body. As the valve core position changes, the cross-sectional area of the fluid passage changes, thus affecting flow rate, pressure, or temperature:
Flow Control: A larger opening results in a larger flow rate; a smaller opening results in a smaller flow rate.
Pressure Regulation: Indirectly affects system pressure by limiting flow rate.
Temperature Control: In heat exchange systems, indirectly controls temperature by adjusting flow rate.
Manual control valve Core Structure
Valve Body: The passage that carries the flow of the medium; the material must be suitable for the characteristics of the medium (e.g., corrosion resistance, high temperature resistance).
Valve Core: The key component that directly controls the flow area; its shape design determines the flow characteristics (e.g., linear, equal percentage).
Valve Stem: Connects the valve core to the operating mechanism, transmitting the operating force.
Operating Mechanism:
Handwheel: Rotates the valve stem by rotating the handwheel (e.g., gate valve, globe valve).
Handle: Directly pushes, pulls, or rotates the handle (e.g., butterfly valve, gate valve).
Worm gear: Used in large-diameter valves to achieve labor-saving operation.
Manual control valve Application Scenarios
Industrial Sector:
Chemical, Petroleum, and Natural Gas: Regulating pipeline flow and controlling reaction conditions.
Electric Power: Regulating steam and cooling water flow to maintain equipment operating temperature.
Water Treatment: Controlling water flow and chemical dosage.
Building Sector:
HVAC: Regulating hot and cold water flow to control indoor temperature.
Fire Protection Systems: Manually controlling fire water flow.
Residential Sector:
Household Water Supply: Regulating faucet flow.
Gas Appliances: Controlling gas stove flame size.
Manual control valve Advantages and Disadvantages
Advantages:
Low cost: No electric or pneumatic actuators required, simple maintenance.
High reliability: No electronic components, low failure rate.
Strong applicability: Can handle high temperature, high pressure, and corrosive media.
Disadvantages:
Limited adjustment accuracy: Relies on manual operation, difficult to automate.
Labor-intensive operation: Large-diameter valves require significant operating force, necessitating the use of worm gears or similar devices.
Manual control valve factory
