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Introduction
This article takes an in depth look at PVC Ball Valves.
You will learn more about topics such as:
What is a PVC Ball Valve?
Types of PVC Ball Valves
PVC Ball Valve Structure
Benefits of PVC Ball Valves
And much more…
Chapter One – What is a Ball Valve?
A PVC or polyvinyl chloride ball valve is a plastic on and off valve that has a rotary ball with a bore where turning the ball a quarter turn can stop the flow of a fluid. They are highly durable, cost effective and can be used to control the flow of water, air, corrosive chemicals, acids, and bases. PVC ball valves have exceptional resistance to low temperatures and pressure with lower mechanical strength. As with all ball valves, PVC ball valves stop the flow by rotating a ball 90°.
At the heart of PVC ball valves is a rotating ball referred to as a rotary ball. A stem at the top of the ball is the mechanism for turning the ball, which can be done manually or automatically depending on the design of the valve. The valve is open when the handle is parallel to the pipe and closed when the handle is perpendicular to the pipe.
PVC ball valves are made of nonflammable plastic that can endure temperatures of -14°C to -140°C. They have many of the same uses as traditional ball valves with a light weight body, compact structure, ease of installation, and the ability to adapt to a wide range of applications.
Chapter Two – Types of PVC Ball Valves
The different types of PVC ball valves are designed to fulfill specific uses. They are classified by their number of ports, types of seats, body assembly, ball access, and the size of the bore. The determining factor for the choice of type of ball valve is the application, which is defined by the pressure, size, temperature, number of ports required, end connectors, and configuration.
PVC ball valves are manufactured from a vinyl resin, which is a thermoplastic material that changes physical properties when heated or cooled. As with all thermoplastics, PVC is an environmentally friendly plastic that can be melted and reshaped several times. Aside from its use in the manufacture of PVC ball valves, PVC is widely used in the production of piping.
PVC Ball Valve Types
Automatic Valves
Automatic PVC ball valves can be two or three way. They have a pneumatic or electric actuator that can be manually controlled with a remote or have a spring mechanism. Automatic actuated PVC ball valves are designed to trigger the ball on the valve to open or close to release or stop media flow and can be used with a wide variety of media from water to gas and oil.
Check Valves
PVC ball check valves are used where backflow could damage the system or cause contamination in filtration and pumping systems. They are an automatic ball valve that releases pressure in a system. PVC check valves are trunnion and are turned off by pressure when the pressure reaches a certain level. They are used in chemical processing, water treatment, and chemical cooling processes. Unlike typical PVC valves, check valves do not have a stem or handle and have a rather simple structure.
Flanged PVC Ball Valve
The uniqueness of flanged PVC ball valves is their connection type, which is a flange. They have a high flow rate because they are normally full bore. Flanged PVC ball valves can have two, three, or four ports, are lightweight, and are easy to install. The thickness of the flange varies according to the pressure of the application. PVC flanged ball valves are connected using bonding glue or bolts with a gasket.
Floating PVC Ball Valve
With a floating PVC ball valve, the ball is suspended in the flow and held in position by compression of its seats. The shaft is connected at the top of the ball and allows a smooth positioning from open to closed with a quarter turn of the handle. When the ball is turned, it is pressed against its seats, which stops the flow. The ball floats inside the valve body, which gives the valve its name.
Full Port PVC Ball Valve
With a full port PVC ball valve, the opening in the ball matches the diameter of the pipeline. Since the hole in the valve is the same size as the pipeline, when the valve is open, the media flow is unrestricted without any form of pressure drop. Full port PVC ball valves are considered to be recovery valves for systems that require low pressure drop and a high flow coefficient.
Manual Operated Valves
Of the various types of PVC ball valves, manually operated ones have the simplest design and are the easiest to use. A two way PVC ball valve is opened by moving the handle such that it is parallel to the pipe. To close the valve, the handle is moved such that it is perpendicular to the pipe. The opening or closing of the valve requires turning the handle a quarter turn in either direction.
For manually operating a three way PVC ball valve, it is important to know the bore design since ports can be in different positions. Turning the handle a quarter turn can change the direction of the flow based on the design of the bore of the valve.
Slip PVC Ball Valve
Slip PVC ball valves have a slip fitting on the inlet and outlet. They can be installed on pipes up to two inches and easily slip onto a pipeline. Slip PVC ball valves are attached using solvent cement with a primer.
Standard Port Valve
A standard port PVC ball valve has the same configuration as a full port PVC valve. The difference between the two is the size of the opening in the ball. Unlike the full port PVC ball valve, the opening on a standard PVC ball valve is slightly smaller than the diameter of the pipeline, which leads to a higher pressure drop and a reduction in the velocity of the flow of the media.
Threaded PVC Ball Valves
Threaded PVC ball valves have internal or external threads to assist in making inlet and outlet connections. Of the various types of PVC ball valves, threaded ones are the most common and are available in several varieties depending on the application and media.
Three Way PVC Ball Valve
The normal configuration of a PVC ball valve is two way with an inlet and outlet. Three way multiport PVC valves with L shaped ports or T shaped, as can be seen in the image below. The L or T shape PVC ball valve can assist mixing, distribution, and diverting of media flow. The two basic port designs can be positioned by turning the valve a quarter turn.
Trunnion PVC Ball Valves
Trunnion PVC ball valves are different from other forms of PVC ball valves. They have a pin at the bottom of the ball that holds it securely in place. The ball is segmented and supported by two shafts at the opposite ends of the ball to retain the ball under pressure. The two supports prevent the ball from shifting or blowing out when it experiences pressure.
V Port PVC Ball Valves
V port PVC ball valves have a V shaped opening or V shaped seat. When the valve is opened, the point or bottom of the V is the first part of the opening that receives the flow. The V shaped configuration provides better control of the flow but necessitates using the highest possible grade of PVC with notches that can be 30°, 60°, or 90°. V shaped PVC ball valves experience high pressure and an increase in the flow rate, which is the reason for the use of exceptionally strong PVC as the base material.
Vented Ball Valves
PVC vented ball valves release the pressure in the media with a small hole placed in the ball. The hole allows the fluid and gas trapped inside the ball to escape, preventing damage to the ball. They are vented internally or externally depending on where the vent is located on the valve and can face upstream or downstream. The purpose of venting is to allow built up pressure that is trapped in the valve, when it is closed, to be released.
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Chapter Three – PVC Ball Valve Structure
The basic material of a PVC ball valve is polyvinyl chloride, which is a vinyl resin. The term PVC refers to different PVC materials that have different strengths, properties, and characteristics. When used for PVC ball valves, the type of PVC is chosen in accordance with the use of the valve.
PVC is widely used in a variety of products. It is a thermoplastic that is chosen for product manufacturing due to its strength and being environmentally friendly. PVC has resistance to water, chemicals, and concentrated acids. It is exceptionally reliable and durable, capable of high performance for many years.
Types of PVC
RPVC
RPVC is rigid PVC that has all of the characteristics and properties that are common to PVC. It is typically used for piping for the construction and plumbing industries. RPVC is capable of withstanding ultraviolet (UV) rays. The strength and stability of RPVC is one of the main reasons that it is chosen to produce PVC ball valves, which need to be capable of withstanding pressure.
CPVC
CPVC is chlorinated PVC that is made like PVC but differs in the chlorination it gets. Chlorine atoms are added to the polymer resin such that it has 60% to 70% chlorine content. As solid plastic, CPVC reacts differently in how it absorbs and releases heat, reacts during cooling and heating, and how it responds to pressure. Products made from CPVC have operating temperatures between 200o F up to 230o F in the proper conditions of pressure and types of chemicals.
The unique properties of CPVC makes it adaptable to a wide range of applications, from residential plumbing to chemical industry synthesis. Though it is not recommended for pressurized gases or air, CPVC can be used in applications with high pressure liquids.
UPVC
UPVC is unplasticized PVC and is not flexible or ductile with the same characteristics as RPVC. As with RPVC, UPVC is used in construction, plumbing, and all the same uses as RPVC. UPVC is highly durable, strong, versatile, and has exceptionally low maintenance.
Plastic UPVC ball valves are used as cut off or connection for pipelines as well as fluid control and regulation. UPVC ball valves were developed to produce pipelines that were resistant to the effects of corrosive materials.
rPVC
rPVC refers to recycled PVC that has been produced from discarded and no longer useful PVC products. The material is melted down and fabricated for use in different products, including PVC ball valves. The strength of rPVC is highly dependent on how it is manufactured.
The Structure of PVC Ball Valves
Various plastic molding processes are used to produce the housings for PVC ball valves. The ball and housing are shaped separately and united during assembly.
Valve Body
The valve body contains all of the parts of the PVC ball valve for turning flow on and off.
Ball Valve Ball
The ball has a center core for media to flow through. PVC ball valve balls come with two way, three way, and four way configurations. The direction of the flow is determined by the turning of the stem.
Stem Mechanism
The stem is connected to the top of the ball and is the external control mechanism for automatically or manually controlling the flow by turning the ball a quarter turn.
PVC Ball Valve Seats
The seats for a PVC ball valve take different shapes depending on the type of valve. They are the lining between the ball and the body of the valve. The seats seal the space between the ball and the valve body. There are many varieties of seats that are used for the sealing and separation process, with EPDM synthetic rubber being one of the choices.
Purpose of Packing
The purpose of packing is to prevent leaks. Packing performs the same function as PVC ball valve seats by sealing the contents of the valve. It is placed around the valve stem and can take the form of O rings. Packing forms a flexible seal around the shaft and stops the media from escaping.
Plastic Handle
The manual operation of a PVC ball valve requires a handle made of solid plastic though hollow plastic handles are also used. The handle connects to the stem and allows for the physical turning of the ball. Handles are treated with UV ray resistant coatings and materials to avoid having them weaken due to exposure to sunlight.
Actuated PVC Ball Valves
Automatic or actuated PVC ball valves are connected to a system that controls the function of the valve. The actuators for PVC ball valves are normally pneumatic or electronic and can be used with two and three way PVC ball valves. The seats for actuated PVC ball valves have to be capable of withstanding the wear the valve endures as well as being able to perform smoothly.
Chapter Four – Benefits of PVC Ball Valves
The normal use for PVC ball valves is to cut off or connect mediums in a pipeline as well as perform fluid control and regulation. There are several advantages to using PVC ball valves compared to ball valves made of other materials. The first and most noticeable benefit is their low cost.
PVC ball valves are versatile and capable of being adapted for a variety of functions. The light body weight and strong resistance to corrosion have made PVC ball valves a valuable tool for a variety of industries.
PVC Ball Valve Benefits
Compact and Seamless
PVC ball valves are compact and seamless, which makes them stronger and prevents them from obstructing the flow of the media.
Maintenance of PVC Ball Valves
The maintenance of PVC ball valves is easy and does not require any form of special tools. They can be manipulated without having to disconnect them from the line. Seals and seats can be easily adjusted to meet the needs of an application.
High Temperature Benefit
Depending on the type of material used to construct the valve, PVC ball valves can withstand extremely high temperatures up to 180o F.
Efficiency Advantage
The seats and seals on PVC ball valves remove the need for lubricating oil since the valve is very tightly sealed and has smooth, flexible material for the movement of the ball.
Valve Affordability
This particular aspect of PVC ball valves is the most prominent. PVC ball valves cost far less than ball valves made of other materials.
Valve Durability
The characteristics and properties of the PVC material guarantees a long life of usefulness for PVC ball valves. The plastic of PVC ball valves is not susceptible to degradation or disintegration, which ensures its long performance life.
Application Adaptability
PVC ball valves can be engineered to fit the needs of nearly every application. They are restricted by some forms of media where the pressure is too great. In the majority of cases, PVC ball valves can fit easily and efficiently with exceptional performance.
As with all ball valves, PVC ball valves come in a wide variety of sizes to suit the needs of any application. The pliability of PVC makes it possible to produce custom designs to fit unique conditions.
Fluid Resistance
Fluid resistance with PVC ball valves is very low and has the lowest fluid resistance of all types of valves. If the ball of the valve has a small diameter, the fluid resistance is still very low.
Light Weight
As would be expected with PVC material, PVC ball valves are very light weight, making them easy to handle and install. Though they are lightweight, they have excellent wear resistance that removes the need for continual maintenance.
Chapter Five – Selecting a PVC Ball Valve
The many benefits of PVC ball valves make them an excellent choice for a wide variety of applications. There are certain factors that need to be considered when making the decision to purchase a ball valve, especially a PVC ball valve. Though PVC is capable of enduring a variety of conditions, when choosing a PVC ball valve, it is important to have the proper match between the valve and the application.
PVC Ball Valve Selection
Bore Design
Though the two way form of PVC valve is the most common, there are other bore designs that can help increase the efficiency of an application. Three-way bore designs include T port and L port configurations useful for applications where there is mixing, distributing, and diverting of the fluid flow. These bore designs can be very helpful with multiple fluids and different types of flow.
Understanding of the Media
One of the reasons for developing the PVC ball valve in the 1950s was media that required special handling. PVC ball valves are suitable for corrosive media such as salt water, acids, bases, salt solutions, and organic solvents, which can damage other materials. An understanding of the characteristics of a media is an essential aspect of the selection process.
Temperature Factor
Temperature is a major factor in many manufacturing applications and has to be carefully considered when choosing PVC ball valves. The chemical structure of the PVC material is the guiding factor when choosing a PVC ball valve since PVC is susceptible to degradation and change under certain circumstances.
Pressure Influence
Much like temperature, pressure strongly influences whether a PVC ball valve is correct for an application. The structure of the PVC can be the determining factor in this case as well.
Conclusion
A PVC or polyvinyl chloride ball valve is a plastic on and off valve that has a rotary ball with a bore where turning the ball a quarter turn can stop the flow of a media.
At the heart of PVC ball valves is a rotating ball referred to as a rotary ball. A stem at the top of the ball is the mechanism for turning the ball, which can be done manually or automatically depending on the design of the valve.
The different types of PVC ball valves are designed to fulfill specific uses. They are classified by the number of ports, types of seats, body assembly, ball access, and the size of the bore.
The basic material of a PVC ball valve is polyvinyl chloride, which is a vinyl resin. The term PVC refers to different PVC materials that have different strengths, properties, and characteristics.
The normal use for PVC ball valves is to cut off or connect mediums in a pipeline as well as perform fluid control and regulation.
Leading Manufacturers and Suppliers
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