All Ball Valves

A ball valve is an extremely durable stop valve that is designed for On/Off function. They provide tight shut-off and high capacity flow with just a quarter turn to operate. The position of the handle immediately indicates whether the valve is open or closed. In the open position there is virtually no obstruction to flow, and head loss through full bore ball valves is almost negligible. Along with being easy to monitor, ball valves have an advantage in that the seat performs a self-wiping action, preventing build-up of foreign particles within the valve.

A ball valve is a shut-off or stop valve that controls the On/Off flow of a liquid or gas. It does this by means of a rotating ball, which when rotated a quarter turn (90 degrees) on its axis provides either high capacity flow or tight shut-off. The position of the handle on the outside of the valve indicates whether it is open or closed.

Ball valves are extremely durable and can be made from a range of materials depending on their intended application, including brass, bronze, stainless steel and PVC. There are three types of ball valves:

• Full Port - the hole in the ball is a minimum of 90% of the size of the hole in the pipe, allowing for maximally unrestricted flow.
• Standard Port - has a port size of between 80% and 90% of the pipe size, providing slightly restricted flow.
• Reduced Port - has a port size of less than 80% of the pipe size and is usually a full size smaller than the pipe, e.g. a reduced port 20mm ball valve will have a 15mm port.

Depending on the application, ball valves can be fitted with various driving devices such as electric, pneumatic and hydraulic actuators.

Ball valves have many advantages including:

• Simple – they have a simple structure and small weight and volume and are easy to install.
• Versatile – they can handle many kinds of liquids and gases at a wide range of pressures and temperatures, making them suitable for a wide range of applications.
• Efficient – they have very low fluid resistance and the Full Port valve has practically none.
• Easy to operate - the simple On/Off operation from full open to full closed is convenient for quick and simple control of gases and fluids .
• Self-cleaning - the seat performs a self-wiping action, preventing a build-up of foreign particles.
• Durable - they have a long service life and provide a reliable seal even when the valve is not in use for long periods.

The body of ball valves may be manufactured from a wide variety of materials, including standard or dezincification resistant brass, stainless steel in a range of grades to suit different applications, PVC, bronze, carbon steel, cast iron or other materials.

A ball valve has a ball and stem and a handle or operating mechanism attached to the stem, which is turned a quarter turn (90°) to rotate the ball on its axis to either block or unblock the flow.

A gate valve has a gate attached to a stem and a wheel that is turned to lower or raise the gate to block or unblock the flow. It takes more than a 360° turn to fully open or close it.

Ball valves and gate valves are both used to control the flow of liquids and gases, but there are some important differences between them that make each more suitable for particular applications:

• Speed - with just a quarter turn (90°) needed, ball valves are best for applications with emergency shut-off requirements.
• Pressure – gate valves are better for high pressure applications where the fast action of a ball valve might create a water hammer (shock wave).
• Actuator – because its status is clear from the position of the handle, a ball valve is better for applications where visual monitoring is required.
• Size – a gate valve can be better for applications with tight installation spaces, as a ball valve’s handle may require more room to operate.
• Flow capacity – gate valves are better for applications requiring larger flow capacities, as they are available in larger diameters than ball valves.
• Seal – applications such as natural gas lines would benefit more from the use of ball valves, which provide a tight seal, even after long periods of time.
• Cleanliness - gate valves are better for food, beverage and pharmaceutical applications, because ball valves are difficult to clean and may cause contamination.
• Cost – because ball valves are superior to gate valves in a number of ways, they are more expensive to buy. But because they are more durable, they are also more economical in the long-term.

A normal 2-way ball valve has a single straight hole through which fluid or gas passes and it is primarily a shut-off valve for stopping and starting the flow.

A 3-way ball valve on the other hand, has three connections or ports, allowing for much more complex flow control processes that a 2-way ball valve simply can’t accomplish. These include the ability to:

• Switch the flow between two sources
• Combine the flow from two sources
• Divert the flow to another destination
• Alternate the flow between two destinations
• Split the flow from one source to two different destinations.

There are two different kinds of 3-way ball valves:

• L-pattern – this is a diverter valve that allows the change of flow from one port to another by turning the valve handle 90 degrees. This changes the position of the ball inside the valve and also the drawing source.
• T-pattern – this is a mixer valve that can be used to direct fluid to more than one location at the same time. When the ball is in the open position, fluid passes through the valve at full pressure to a primary destination, while also travelling to a second destination at a slightly lower pressure.

3-way ball valves have stops built into their handles or on their mounting pads to prevent the valve from being turned more than 90 or 180 degrees at a time. This limiting of movement allows for more control over the amount of fluid that is being diverted or combined.

The main advantage of a 3-way valve is its cost-effectiveness. It is able to do the work of two 2-way ball valves, operating as both a control and a shut-off valve. Consequently, it is used widely in applications such as the heating, ventilation, air conditioning and cooling (HVAC), mining and industrial sectors.

Ball valves are highly versatile valves that are widely used in a number of industries including oil and natural gas, manufacturing, chemical storage and residential plumbing.

They have a wide range of applications including:

• Flow and pressure control and shut-off for corrosive fluids, slurries, liquids and gases
• Fluid shut-off in upstream oil and gas production facilities, both onshore and offshore
• Fluid shut-off from compressed air lines to high pressure hydraulic systems
• Low point drains and high point vents in liquid, gaseous, and other fluid services
• Cooling water and feed water systems
• Drinking water applications for flow and pressure control (they must be WaterMark approved for use in Australia)
• With natural gases, liquified petroleum gases, manufactured gases and air.
• For mains and branch line shut offs in residential plumbing
• For connecting instruments via instrument tubing
• In high temperature and high pressure applications.

Ball valves also have a number of advantages over other types of valves including:

• Bubble-tight sealing
• Fast opening and closing
• Compact size and lightweight
• Versatile multi-port design options, reducing the number of valves required
• Reliable sealing, even in dirty media
• A simple structure that’s easy to install and operate
• Low pressure drop and relatively high flow capacity
• A multitude of types and configurations to choose from
• Excellent durability over many years of service, requiring minimal servicing and repairs
• Available in different configurations to suit specific ranges of pressures and temperatures.

Ball valves have few disadvantages including:

• Control of flow limited to on and off, unless specially adapted balls are used
• Water hammer effect when the ball moves quickly to closed position
• Easily damageable seats in presence of unfiltered particulated media
• Inadequate for food management, unless the cavity is appropriately filled
• Subject to severe damage with low temperature water, unless specifically designed for that purpose

Overall, ball valves are versatile and have many advantages that make them the number one choice for a myriad of different environments and applications.

Ball valves are designed to allow either complete flow or total shut-off and are not designed to control the flow of substances at different rates (throttling). If a valve is kept in a semi-on or off position, there is a high risk of damage to the edge of the ball opening. Globe or needle valves are a better choice when precise and reliable flow control is required.