First, the gate valve
Gate valves, also known as gate valves or sluice valves, are one of the most commonly used types of valves in piping systems. They provide a tight seal and are ideal for applications where full flow is required without restriction.
The working principle of a gate valve involves a flat or wedge-shaped gate that moves perpendicular to the flow direction. When the valve stem is turned, the gate lifts or lowers, allowing or blocking the flow of the medium. This makes it an effective shut-off device in pipelines.
Advantages include low fluid resistance, minimal erosion on the sealing surfaces when fully open, bidirectional flow capability, durability, and suitability for both small and large sizes. However, gate valves have some drawbacks such as a larger height requirement, longer opening and closing time, and difficulty in maintenance, especially for large diameter valves.
Gate valves can be classified based on the stem type (rising or non-rising), the gate structure (parallel or wedge-shaped), and whether they have a single or double gate.
Second, the globe valve
Globe valves are another widely used type of valve, typically with a nominal size below 100mm. They function similarly to gate valves but differ in that the closing member (disc) moves along the centerline of the seat. This design allows for better control of flow and pressure.
Globe valves are easy to manufacture, maintain, and durable. However, they have directional flow requirements and tend to have higher flow resistance and less effective sealing compared to other valve types.
Common types include straight-through, right-angle, direct current, and balanced designs. In engineering applications, flange-mounted (J41H) and internally threaded (J11H) versions are frequently used. These valves must be installed in the correct direction and should not be reversed.
Third, the ball valve
Ball valves are a more modern type of valve that has gained popularity due to their efficiency and reliability. The working principle involves a spherical disc with a bore that rotates 90 degrees to either allow or block the flow. This makes them ideal for quick shutoff applications.
Compared to gate and globe valves, ball valves offer advantages like compact size, excellent sealing (zero leakage), and ease of operation. They are widely used in industries such as petrochemical, power generation, and aerospace.
However, ball valves can be difficult to maintain, especially if the internal components become damaged. There are two main types: floating ball and fixed ball valves.
Fourth, the butterfly valve
Butterfly valves are among the most commonly used valves in heating systems. Their simple design and lightweight construction make them easy to operate and install.
The working principle involves a disc that rotates around a central shaft within the valve body. By rotating 90 degrees, the disc opens or closes the passage, making it suitable for both shutoff and flow regulation.
Advantages include a simple structure, light weight, good sealing performance, and cost-effectiveness. However, when fully open, the disc may be exposed to media erosion over time.
In heating projects, three eccentric metal-sealed and rubber-sealed butterfly valves are commonly used.
Fifth, the check valve
Check valves, also known as non-return valves or one-way valves, are essential in preventing backflow in piping systems. They operate automatically by relying on fluid pressure or the weight of the disc to open or close.
These valves are often installed at pump outlets to prevent water hammer and protect equipment. Common types in heating systems include horizontal lift (H41H), single-lobed swing (H44H), and double-lobed butterfly (H77H).
Sixth, the regulating valve
Regulating valves, also called throttle valves, are used in secondary heating networks to control flow distribution and achieve thermal balance. They resemble globe valves in structure but differ in how the flow area is adjusted.
The valve disc functions like a stopper in a thermos bottle, adjusting the flow area as it moves. A scale on the valve stem indicates the flow setting. While the straight-through type (T41H) is common, it has high flow resistance and should not be installed vertically.
As technology advances, balancing valves (PH45F) have largely replaced traditional regulating valves due to improved flow characteristics and reduced resistance.
Seventh, the balancing valve
Balance valves are an improved version of regulating valves. They feature a direct-flow channel and a polytetrafluoroethylene (PTFE) valve seat, which reduces flow resistance and enhances sealing.
They also offer a shut-off function, making them ideal for variable flow systems in heating stations. Balancing valves are directional and can be installed horizontally or vertically.
Eighth, the self-operated balancing valve
Self-operated balancing valves, also known as flow control valves, use a spring and diaphragm mechanism inside the valve to regulate flow automatically. If the flow increases, the mechanism adjusts to reduce the flow area and restore the set value.
These valves are commonly installed at branch points in heating systems to eliminate hydraulic imbalance, improve system efficiency, and ensure economic operation. They must be installed in the correct direction and cannot be reversed.
Ninth, the safety valve
Safety valves are critical for protecting systems from overpressure. When the pressure exceeds the set limit, the valve automatically opens to release excess pressure. Once the pressure returns to normal, it closes automatically to maintain system integrity.
Safety valves come in different types, including spring-loaded, lever-type, and pulse-type. They can be classified based on the degree of opening (micro-open or full-open) and the method of discharge (closed or open type).
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