Characterized Ball Valve

Figure 1: Belimo characterized control valve

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Characterized ball valves are modified ball valves designed specifically for fluid control. The bore shape in a characterized ball valve can be customized to a 'V,' 'U', or parabolic shape to suit the application's specific requirements. They are used for controlling and modulating flow, offering stability and precision. Characterized ball valves are particularly useful in applications like HVAC systems, where maintaining consistent temperatures is crucial for comfort and energy efficiency. Their main features are:

• Equal percentage flow characteristic: A characterized ball valve controls the flow of liquid or gas consistently as it opens and closes, maintaining a steady temperature or pressure.

• Excellent control stability: The special disc inside the valve helps control flow smoothly and evenly. This can increase the lifespan of the actuator.

• Eliminates multiple pipe reduction: Certain systems might need to use smaller pipes to control flow as smaller pipes inherently restrict flow, which can help achieve a certain level of control. However, using smaller pipes can also lead to increased pressure drops and energy losses. A characterized ball valve can precisely control flow rates without solely relying on smaller pipes.

Read our v-port ball valve article for more information on the design and applications.

Standard ball valve vs characterized ball valve

Standard ball valves

Ball valves are excellent for on/off applications. However, they are not designed to modulate or regulate the flow steadily. They allow large fluid flow (high Cv or Kv) relative to their size, making them unsuitable as modulating control devices. This makes it difficult for ball valves to maintain or modulate a consistent temperature, as they can't steadily control the amount of hot or cold medium passing through. For example, for a ball valve that regulates hot water to control the temperature of a system, the abrupt changes in flow could lead to sudden temperature fluctuations, making it difficult to maintain a stable temperature.

In a regular ball valve, the bore through the ball is typically round; it aligns with the pipeline when the valve is fully open (Figure 2 left). When the valve is partially open, the flow path becomes restricted by the circular shape of the bore, meaning even a slight movement of the valve can result in a significant change in the flow rate.

Characterized ball valve

Characterized ball valves have specialized bore shapes for more controlled and predictable flow characteristics (Figure 2 right). The characterized ball valve combines the shut-off capabilities of a ball valve with a characterized disc, ensuring an equal percentage flow characteristic. An equal percentage flow characteristic implies:

• A flow behavior where each increment of valve position change delivers a constant percentage change in flow rate, providing precise and stable control over wide load changes.

• A steady thermal output (how hot or cold something gets) that varies linearly based on how much the valve is opened.

A characterized ball valve allows for greater control and precision in managing the flow rate, especially under varying load conditions. This improves system efficiency, stability, and responsiveness, making it ideal for applications with large load changes.

Figure 2: Normal ball valve disc (left) and the special disk pattern in a characterized ball valve (right).

Standard and characterized ball valve flow profiles

Standard ball valve

Figure 3: The flow profile and heat emission in a standard ball valve: ideal flow (A), standard ball valve flow (B), and resulting heat output in a standard ball valve (C)

Figure 3 shows the flow and heat emission relationship when a standard ball valve opens incrementally.

• A: Ideal flow characteristic. The flow and heat emission do not increase abruptly with changes in the valve opening.

• B: Standard ball valve flow characteristics

• C: Resulting heat output in a standard ball valve

The resulting heat does not vary linearly (increases abruptly) with the valve opening (flow) degree. For example, the heat output is 'P' in a valve that is 40% opened.

Characterized ball valve

Figure 4: The flow profile and heat emission in a characterized ball valve: a characterized ball valve's flow profile (A) and linear heat output (B)

Figure 4 shows the flow and heat emission relationship when a characterized ball valve opens incrementally.

• A: A characterized ball valve's equal percentage flow profile

• B: Linear heat output

In a characterized ball valve that is 40% opened, the resulting heat dissipation is P1, which is much less than P (in the case of a standard ball valve). The resulting heat output varies linearly with the degree opening (or flow).

Characterized ball valve vs globe valve

The main advantage of a globe valve over a standard ball valve is its superior flow control capability. The Cv values of characterized ball valves match those of globe valves of the same size, meaning they can control flow as effectively. However, characterized ball valves have the following advantages over globe valves:

• Higher pressure resistance: Characterized ball valves can withstand higher pressure than globe valves of similar size. This is due to their streamlined design, which minimizes pressure drop and enhances structural integrity.

• Leak-proof: Unlike globe valves, characterized ball valves offer a leak-proof seal, which allows a small amount of leakage and low-pressure drops.

FAQs

What is a characterized ball valve?

A characterized ball valve is a special type with a shaped disc or insert to achieve more precise flow control or alter the valve's flow characteristics.

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When should I use a characterized ball valve?

Use a characterized ball valve when you need precise flow control or when you wish to customize the valve's flow characteristics.

Product features of ball valve:
1. The three-way ball valve adopts an integrated structure in structure, with a four-sided valve seat sealing type, fewer flange connections, high reliability, and a lightweight design.

2. The three-way ball core is divided into T type and L type, with long service life, large circulation capacity and low resistance.

3. The ball valve is divided into two types: single-acting and double-acting according to the action type. The single-acting type is characterized in that once the power source fails, the ball valve will be in the state required by the control system.

Advantages of ball valve:

1. The fluid resistance is small, and its resistance coefficient is equal to that of a pipe section of the same length.

2. Simple structure, small size and light weight.

3. It is tight and reliable, and the sealing surface material of the ball valve is widely used in plastics and has good sealing performance. It has also been widely used in vacuum systems.

4. It is easy to operate and open and close quickly. It only needs to rotate 90° from fully open to fully closed, which is convenient for remote control.

5. The maintenance is convenient, the structure of the ball valve is simple, the sealing ring is generally movable, and it is convenient to disassemble and replace.

6. It has a wide range of applications, with a diameter ranging from a few millimeters to a few meters, and can be applied in high vacuum or high pressure.

This type of valve is a high-pressure ball valve commonly used in existing mines. It bears high pressure and adopts a U-shaped card quick connection method. It can be quickly installed and disassembled in the daily production and use of the mine, and is convenient to use.

The ash unloading ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. The ash unloading ball valve can be divided into floating ball type, fixed ball type, and elastic ball type. The ash unloading ball valve is mainly used to cut off or connect the medium in the pipeline. It can also be used for fluid adjustment and control. The ash unloading ball valve Compared with other valve types, it has angular stroke output torque, opens quickly, is stable and reliable, and is widely applicable. The working principle of the ash unloading ball valve is to make the valve unblocked or blocked by rotating the valve.

Electric ball valve structure is composed of only a few parts, saving data; small size, light weight, small installation size, electric ball valve structure diagram, small driving torque, pressure regulating valve, easy and agile operation, only need to rotate 90° Fast opening and closing; and also has a good flow regulation effect and sealing characteristics at the same time, in the application of large and medium caliber, medium and low pressure, electric ball valve is the dominant valve form. When the electric ball valve is in the fully open position, the thickness of the butterfly plate is the resistance when the medium flows through the valve body, so the pressure drop that occurs through the valve is small, so it has better flow control characteristics. Electric ball valves have two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be embedded in the valve body or attached to the periphery of the butterfly plate. Valves with metal seals generally have a longer life than valves with elastic seals, but it is difficult to achieve a complete seal. Metal seals can adapt to higher operating temperatures, while elastic seals have the disadvantage of being limited by temperature. If the electric ball valve is requested to be used as a flow control, it is important to accurately select the size and type of the valve. The construction principle of the electric ball valve is particularly suitable for manufacturing large diameter valves. Electric ball valves are not only widely used in general industries such as petroleum, gas, chemical, and water disposal, but also used in cooling water systems of thermal power stations. Commonly used electric ball valves include wafer type electric ball valves and flange type electric ball valves. Wafer type electric ball valve uses double-head bolts to connect the valve between two pipe flanges. Flange type electric ball valve is equipped with flanges on the valve. The two flanges on the valve are connected to the pipe flanges with bolts. The strength performance of the valve refers to the ability of the valve to withstand medium pressure. The valve is a mechanical product that is subjected to internal pressure, so it must have sufficient strength and rigidity to ensure long-term use without cracking or deformation. Pneumatic ball valve is composed of ball valve and pneumatic actuator. Pneumatic actuator is divided into double-acting pneumatic actuator and single-acting pneumatic actuator. Through solenoid valve control, ball valve switching action is realized. The pneumatic ball valve can realize intelligent control, quickly open or close the pipeline, and can effectively control and manage the pipe network.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

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