Ball valves are widely used in plumbing and piping systems, in fact, they are one of the most common valve types. In case you aren’t familiar with them, a ball valve is a quarter-turn valve with a ball closure element. The ball has a hole through its center, which allows fluid to flow through the valve when it opens. A 90-degree turn places the surface of the ball in the flow path, preventing flow through the valve and providing effective shutoff. A stem attached at the top of the ball extends outwards through the top of the valve, connecting to a handle or actuator, allowing for valve operation.
Ball valves come in many designs: standard port, full port, multi-port and v-port (for flow control). Ball valves are known for their durability, versatility, performance and cost effectiveness. Quality ball valves can maintain their performance after many operating cycles, seal tightly, handle high pressure, hot and cold temperatures, and require little maintenance.
Apollo FNPT threaded ball valve with lever
Ball valves are popular in industrial applications, with high-pressure designs rated up to 10,000–15,000 psi (roughly 700–1,000 bar) and specialized metal-seated valves rated for temperatures up to 1,200°F (650°C). Read our article about the types of ball valves to learn more about different ball valve designs and configurations. You might not know that, while ball valves are typically used for shut-off, or on-off applications, they can also be used as flow control valves.
Flow control with ball valves
Standard, ‘off the shelf’ ball valves aren’t the best flow control valves, however they still find widespread use because of their cost effectiveness. Coming in standard (reduced port) and full port configurations, these valves may be used for applications that don’t require precise flow regulation and fine flow adjustment.
V-port ball valves are specialized ball valves designed for flow control applications. These valves possess a unique design: a V-notch or similar contoured shape on the ball (or seat)m which gives V-port ball valves an equal percentage flow characteristic. This allows for stable and precise flow control.
V-port ball valves may be fitted with actuators and integrated with a plant's control system, providing a complete process control valve solution.
Advantages of ball valves for flow control
Below are some advantages of using ball valves as flow control valves:
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Ball valves have a high turndown ratio (that is the ratio of maximum to minimum flow).
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Offers low flow resistance and a low pressure drop across the valve.
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Quarter-turn design ensures a fast acting device.
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Can operate at high pressure and temperature ranges.
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Minimal leakage when fully shut.
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The sealing surface is self-cleaning.
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Represents a relatively small size, light-weight and cost effective valve solution.
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Multiple material, connection and actuation options are available.
Disadvantages of ball valves for flow control
Disadvantages of using ball valves as control valves include:
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Poor throttling capability, particularly at low flows.
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Valve internals are worn down at small valve opening positions, due to high velocity.
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Imprecise flow adjustment and regulation, does not allow for fine control of fluid flow.
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Quick opening and closing can result in pressure surges.
Here’s where V-port ball valves come into play. They are specially designed for flow control applications, offering precise control and adjustment, combined with the durability and reliability associated with ball valves.
How does the v-port ball valve control flow?
A already discussed, the v-port design allows for more precise and controlled flow regulation. It produces an equal percentage flow characteristic, meaning equal increments of ball rotation produce an equal percentage change in the existing flow rate — giving fine control at low openings and larger changes at high openings. This is desirable for accurate, precision flow control.
AVCO stainless steel V-port ball valve with different ball geometry options
As a v-port ball valve is opened, the small end of the v-shaped opening allows fluid flow through the valve at high velocity. Valves are supplied with specialized trims or hardened materials to cater for these conditions. The flow rate through the valve continues to increase almost linearly as the valve is turned to the fully open state. A variety of v-port shapes are available to suit application requirements, with the most common being 30°, 60°and 90°.
V-port ball valves retain the advantages of standard port ball valves, such as leak-tight sealing, quick operation and durability. They also have far better flow control capabilities, making many of them comparable to globe valves for general process throttling, though needle valves remain the preferred choice for fine, low-flow precision metering. V-port ball valves find use in a broad range of applications including chemical processing, oil and gas, mining, pulp and paper, agriculture, water treatment, and power generation.
Final Thoughts on Control Ball Valves
Understanding ball valve capabilities is crucial in selecting a valve that works best for your application. Standard and full port ball valves are best suited to on-off duties. While they may be a cost-effective option for flow control, they are typically not suited to flow control in an industrial setting. V-port ball valves offer precise and predictable flow control performance, with a high flow capacity and low pressure drop across the valve. V-ported ball valves are sometimes available with drop-in form factors, allowing for easy replacement of standard ball valves.
If you’re still not sure which type of ball valve suits your application, if you need help with valve selection, or if you have any technical questions, be sure to get in touch with a valve professional.
