What is the common port on a 3-way valve?

13 Apr.,2024

 

What is a 3-Way Valve?

A 3-way valve has three ports. The 3-way ball valve is one of the main 3-way valves, which can be used to maintain fluid or gas flow through a piping system. The valve has a primary flow path, which connects two ports, and a secondary flow path, which connects the main flow path to the third port. The fluid or gas flow can be redirected as needed by opening and closing the valve in various ways.

Brass 3-way ball valve

Why do we need a 3-way valve?

The 3-way valve is vital in many fluid and gas handling systems because it allows for precise flow, direction, and pressure control. Some of the key benefits and uses of 3-way valves include:

  • Diverter or mixing applications:

A 3-way valve can divert the flow of a fluid or gas between two different output ports or mix two various liquids or gases into a single output port.

  • Regulating flow rate:

The flow capacity of a gas or fluid can be regulated by controlling the opening and closing of the various flow paths in a 3-way valve.

  • Reducing installation cost:

A single 3-way valve can often replace two separate valves, reducing the installation cost and space requirements.

  • Simplifying control systems:

3-way valves can be combined with sensors and controllers to create more complex and automated control systems.

  • Providing fail-safe operation:

In some applications, 3-way valves can be designed to fail in a safe position, reducing the risk of damage or injury.

How does a 3-way valve work?

3-way flow types

A 3-way valve provides three different pathways for fluid or gas to flow through, each of which can be controlled to either block or allow flow. The valve typically consists of a central body with three ports: one inlet and two outlet ports. The main flow path connects the inlet port to one of the outlet ports, while the secondary flow path connects the main flow path to the other outlet port.

When the valve is in the sealed position, both the primary and secondary flow paths are blocked, and no fluid or gas can flow through the valve. When the valve is in open condition, one of the outlet ports is connected to the inlet port via the main flow path. In contrast, the other outlet port is connected to the inlet port via the secondary flow path.

Adjusting the valve’s position allows the fluid or gas flow to be redirected between the two outlet ports or shut off entirely. Sometimes, a 3-way valve may mix two streams of fluid or gas by partially opening both outlet ports and allowing them to combine in the main flow path. 

What are the types of 3-way valves?

The T-port and L-port valves are known as three-way valves due to their T shape body with 3-parts. Both divert flow to and from the various parts. Yet, the L port valve permits one action, whereas the T port valve facilitates another. Here are the main types of three-way valves:

T-port valve:

bronze t lf port valve

This type of valve has a T-shaped bore, allowing flow through the valve in three directions. This valve can mix, divert, or bypass fluid flows.

How does the T-port valve work?

A T-port three-way valve is a type of valve that has a T-shaped bore or flow path. It allows flow through the valve in three directions and can be used for mixing, diverting, or bypassing fluid flows.

The valve has three ports: the inlet port, the outlet port, and the standard port. The common port is connected to the T-shaped bore, where the fluid or gas flow is controlled.

T-port three-way valves can be designed with different actuation mechanisms. When the valve is actuated, a disc or plug inside the valve rotates or moves to redirect the flow path to the desired port.

The T Port Valve is typically used to direct flow in both directions. Fluid is continuously required to multiple locations, passing through the valve body and the side port at a slightly lower pressure.

t port

L-port three-way valve:

This type of valve has an L-shaped bore and can be used to divert fluid flow between two ports or mix two different fluid streams.

Working of L-port three-way valve

Most of the time, the L Port valve is used to make the flow from two different sources flow in an identical direction. For instance, when emptying tanks, you can draw fluid from the next tank to the same line by turning the handle to switch the source.

L and T port comparison

Maintenance of three-way valve

Proper maintenance of a 3-way valve is vital to ensure its reliable and safe operation. Here are some general maintenance tips for 3-way valves:

  • Regular inspection:

Periodic inspection of the valve body, stem, and other components can help identify any signs of wear, damage, or leaks. Any abnormalities should be addressed promptly.

  • Lubrication:

The valve stems, and seat may need lubrication to reduce friction and wear. Use the manufacturer’s recommended lubricants and apply them according to the recommended schedule.

  • Cleaning:

Cleaning the valve internals may be necessary to remove any buildup of sediment or debris that may cause clogging or damage to the valve components.

  • Actuator maintenance:

Regular maintenance, including checking the air or hydraulic pressure, can help ensure proper valve operation if the valve has an actuator.

  • Calibration:

If the valve has position indicators, they should be calibrated periodically to ensure that they are providing accurate readings.

  • Replacement of worn parts:

Suppose any valve components are worn or damaged during the inspection. In that case, they should be replaced promptly to prevent further damage or failure of the valve.

3-way cartridge valve

Properties of 3-way ball valve

A 3-way ball valve is a type of valve that has three ports or openings in the ball, allowing for flow redirection between multiple pipes or systems. Here are some properties of 3-way ball valves:

  • Versatility:

3-way ball valves can be used for various applications, including diverting flow, mixing flow, or isolating flow between two systems.

  • Minimal leakage:

The design of the 3-way ball valve ensures minimal leakage, providing a tight seal that minimizes the risk of leaks or drips.

  • Low maintenance:

3-way ball valves are relatively low-maintenance due to their simple design and few moving parts, making them a reliable and cost-effective solution.

three-way ball valves
  • High temperature and pressure resistance:

3-way ball valves are suitable for high-temperature and high-pressure applications, making them ideal for various industries.

  • Corrosion-resistant:

Depending on the material used in construction, 3-way ball valves can resist corrosion, making them suitable for harsh or corrosive environments.

  • Easy to operate:

3-way ball valves are generally easy to use, with simple handle or lever mechanisms for opening and closing the valve.

  • Multiple port options:

Depending on the application, 3-way ball valves can be designed with different port configurations, such as T-port or L-port.

  • Buying guide for 3-way ball valve

If you are looking to buy a 3-way ball valve, here are some factors to consider:

  1. Valve Type:

Different types of 3-way ball valves exist, including L-port and T-port valves. Determine the type of valve that best suits your application needs.

  • Valve Size:

Choose a valve size appropriate for your system’s flow rate and pressure requirements.

  • Material:

Consider the fluid or gas being conveyed through the valve and choose a material that is compatible with the liquid or gas. Materials used for 3-way ball valves include brass, stainless steel, and PVC.

  • End Connections:

Determine the type of end connections that will be needed for your application. Common end connection types include threaded, flanged, and welded.

  • Port Configuration:

Decide on the port configuration of the valve, including the inlet, outlet, and standard ports. Ensure the valve you choose has the port configuration matching your application requirements.

  • Actuation:

Determine the actuation mechanism needed for your application, including manual, electric, pneumatic, or hydraulic.

  • Cost:

Consider the cost of the valve and compare prices from different valve manufacturers or suppliers.

  • Application Specifics:

Consider any other specific requirements for your application, such as temperature or pressure limitations, flow direction, or the need for special features like locking handles or stem extensions.


To understand the "T"-port and an "L"-port 3-way valves and what makes them different, it's important first to establish what each of these terms mean. By clearly defining each term, the difference in directional flow purpose will be easier to understand. First, let's define exactly what a diverter valve does.

In simple comparison, a 3-way valve has one more port than a 2-way valve. But why? A two-way valve allows fluid to enter the valve from one port, and exit through the other. Having a third port, allows fluid an alternate path of travel, either when exiting or entering the valve. This permits fluid to either exit the valve from more than one point, or enter the valve from more than one point.

Several industrial applications use 2-way valves that provide on/off fluid service. Applications that require constant flow utilize 3-way valves, which contain three connection ports, having A, B and AB labels. 3-way valves can divert fluid flow to two directions or mix fluids from two different sources.

When using 3-way valves for mixing, fluids enter the valve body through ports A and B. The service fluids with different physical or chemical properties mix within the valve body before transmission through the outlet port AB. 3-way mixing valves are vital for combining liquids or gases with different temperatures and pressure, before sending them through the outlet with the desired properties.

For 3-way diverting valves, port AB acts as the inlet, while ports A and B become the outlets. Turning the spindle directs the flow to the left or right, upwards or downwards, depending on the orientation of the piping system. When flow moves from AB to A, the valve blocks fluid flow to port B. Changing the position of the spindle redirects the flow of fluids from AB to B and blocks the flow to port A.

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3-way valves are available in two internal structures. They are either L-type (L-port) or T-type (T-port) valves. The internal structures of the valve determine the flow patterns past the valve body. The T-port design is suitable for distributing common inlets to different destinations and the L-port design facilitates mixing from multiple sources to common outlets. 3-way valves, like the 2-way counterparts, can use actuators that improve their responsiveness and enhance precision in different industrial applications.

The multiport configurations of 3-way valves make them cost-effective alternatives to using multiple 2-way valves with complex automation. A single 3-way valve can provide directional fluid control and shut off. These valves offer reliable fluid service in heating and cooling applications, steam and boiler applications, chemical mixing processes, hydraulic and pneumatic applications. 3-way valves are also suitable for use as by-pass valves in pipe systems having primary and secondary loops.

L-Port Versus T-Port 3 Way Valves

There are different multi-port valves available in the market, ranging from 3-way ball valves, 3-way globe valves, 3-way butterfly valves and 3-way gate valves. 3-way ball valves are the most popular due to their simple design, ease of actuation and durability. The control of fluids past these valves depends on:

  • The pipe set up: is the pipe system horizontal or vertical?

  • The direction of handle rotation

  • Design of the port: L-port or T-port?

The subsequent discussions regarding L-port and T-port designs refer to 3-way ball valves. Valve manufacturers provide arrows on the valve handles that mimic the fluid flow paths through the control mechanism. These marks indicate flow directions.

L-Port Valves

The L-port, L-pattern valve allows the convergence of fluid from two different inlet ports without ever using the same inlet port and directs it to a common outlet. They have two inlets and one outlet port. L-port valves can provide fluid diversion service in some applications. Assume inlet ports (A and B) are horizontal, and the lower port (AB) is the outlet. The initial flow is from the inlet port (B) to the outlet (port AB).

Possible Flow Positions (A, B, C and D) In The L-Port Valve

Shifting the valve lever or the actuator through 90° clockwise changes flow direction from port A to common outlet AB.

Turning the lever through another quarter-turn moves the valve through 180°. At this point, the 3-way valve shuts off the flow of fluid past the valve. Some L-port valves can move through 360°, providing two shut-off positions. In a vertical L-port orientation, the outlet port (AB) is always in an open position.

Applications of L-port Valves

The versatility of L-port valves implies that they can provide shut-off, directional control, fluid diversion or bypass where necessary. A typical application of L-port valves (vertical or horizontal) is alternating sources of fluids in a process.

T-Port Valves

T-port valves primarily divert fluids from one source to different outlets or mix two sources to a single outline. The valves split or divide the flow of fluids into two directions. Flow enters the valves through one inlet and flows to two destinations.

T-port or mixer valves can have all three ports open at once. The T-pattern allows the service media to flow in two opposite directions or a straight-through flow. The common port is always open if the T-port valve is vertically-configured.

Possible Flow Positions (A, B, C and D) In The T-Port Valve

Turning the valve lever or actuator through a quarter-turn diverts the flow of fluids to either direction - like an L-port valve. T-port valves cannot provide an "all ports closed" configuration. Three-way valves can have lock handles that prevent the flow control mechanisms from exceeding the 90° turns, however, they can also have 180° or 360° rotation. Limiting the motion of the ball or flapper offers better control over the volumes of fluid to divert or mix within the valve body.

Applications of T-port Valves

T-port valves can provide constant fluid flow service, media mixing and sampling. They are also suitable for use as bypass valves. Some general industrial applications of T-ported valves include:

  • Merging fluid flow from two different sources. For instance, in a piping system in a beverage production line, the valve may serve as a primary combination point for fluids coming from a pure water line and a juice concentrate storage tank.

  • Diverting flow from a single source to two different destinations at once. It’s important to keep the pressures of the inlets balanced and higher than the outlet port in order to allow for a smooth mixing process

  • Changing flow between two storage tanks or destinations (when used like an L-port valve)

Tips For Selecting and Maintaining 3 Way Valves

There are a few guidelines that pipeline engineers and designers should consider when selecting 3-way valves for different industrial applications. Some critical tips include:

  • Choose the appropriate valve sizes. Undersizing the 3-way valve will increase the pumping costs of the system. Oversizing the valve reduces pumping costs but will cause control inaccuracies. Valve movements at the beginning and the end of travel will have minimal effects on the distribution of fluids past the ports.

  • Evaluate the physical and chemical qualities of the service fluids. If using the valve for mixing, the valve material and sealing components must be compatible with the service media. Valve materials must adhere to statutory regulations and certification standards

  • The pressure and temperature ratings of the 3-way valves should accommodate the flow conditions and variations of the service fluid.

  • Confirm the connection types of the 3-way valves to ensure they are compatible with the existing pipelines. When choosing the valves, select a connection method that will simplify the maintenance of the piping system, valves and actuators. 3-way valves having flanged connections are easier to maintain and replace than their welded counterparts.

  • Also, consider the actuation mechanisms. What type of actuators will meet the requirements of the piping system?

Conclusion

The multiport configurations of 3-way valves allow better flexibility and control in different industrial applications. The valves have different internal designs that give them unique performance characteristics. The capability of a single 3-way valve to handle the diverse flow applications implies that fewer valves are required. It reduces the cost of installation, operations and maintenance. If you’re unsure in your selection, make sure to consult a valve engineer at ValveMan.com to help you make the right decision.

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Jason Welsford is the third-generation owner of the FS Welsford Company and a highly regarded expert in the valve industry. Under his leadership, ValveMan.com has grown into a leading online platform for valves and valve-related products. Leveraging his extensive knowledge of business operations and various valve systems, Jason offers tailored solutions across diverse sectors. Known for his collaborative approach and leadership skills, he consistently ensures successful project outcomes. With a commitment to innovation and excellence, Jason continues to shape the future of the valve industry.

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