Ball Valves: How It Works, Types And Common Applications

 

 

Ball valves are specially designed valves that are used in pipeline applications to turn off and on flow of a substance. For instance, they're commonly used in gas processing, plumbing and industrial piping systems to control the flow of a gas or liquid through a pipe. And they're also used in food and beverage systems, including in brewing, water pipeline systems and liquid food processing factories.

A ball valve is made up of several pieces, including a floating ball, stem, seat, and handle.

Here's how the system works: The valve features a pivoting ball, with an opening in the middle that is connected to a stem and handle. With a quarter turn of the handle, the ball's opening comes into alignment with the pipeline flow, enabling a liquid or gas to flow freely through the valve. When the ball opening is in the off position, the flow of a substance is blocked.

Ball valves are most commonly used because they provide fast, effective shutoff of a system. Plus, they are durable, provide a secure seal for long periods of use, and they're easy to repair and operate. Thus, these types of valves are often preferred over other quarter-turn stopping valves.

 

Common Types of Ball Valves

In general, there are five types of ball valves that provide a similar function and are operated the same. The biggest difference, though, is in body construction and how the balls are contained in the assembly's casing. Body styles include split body, top entry, single body, three-piece body and welded.

Plus, ball valves are also determined by the type of opening within the ball. Different types of bores result in added precision when turning off the valve, they can contain more than one open or closed setting, and they can be fashioned to prevent buildup behind the ball. The size of the bore, or port, can also be the same size as the pipeline or a reduced size, which results in a restricted flow. Bore types include:

Full Port Ball Valves: The floating ball of a full-port ball valve is oversized, and the bore is the same size as the pipeline. This results in the free flow of a substance, and that's why full port ball valves are commonly used in oil and gas pipelines, as a flow restriction can disrupt the material and cause buildup. These valves are larger, and thus they're more expensive.

Reduced Port Ball Valves: As known as reduced-bore or standard ball valves, the bore in this type of valve is smaller compared to the pipeline, and thus flow is restricted and pressure drops. These are typically used when flow rate is not a major concern. Plus, they're smaller and more cost-effective compared to full-port valves.

Cavity Filled Ball Valves: The constant flow of gas or liquid through a ball valve can result in buildup behind the ball. A cavity filled ball valve prevents this from happening. This type of valve has a seat, or casing, that completely surrounds the floating ball to prevent buildup. They're commonly used in systems where this buildup could result in bacteria, i.e. in brewing and food systems, or where a material can crystallize behind the ball like paint.

V Port Ball Valves: Instead of a cylindrical-shaped bore, the V Port ball valve has a v-shaped bore or seat. Thus, as the valve moves from off to on, the narrower end of the V is positioned in front of the flow, and slowly, as the wider parts of V-shaped bore reach the pipeline more material can flow through the valve. This results in greater precision and more control, compared to other styles.

 

Buyer's Tips

Choose a valve that will fit the size of your piping; there are ball valves available in all standard pipe sizes. Generally, standard, reduced-flow ball valves are the most typical type of valve available. Plus, you'll also want to choose a valve with the correct threading. The most common options include female-female threading, i.e. both pipeline openings would be male, or non-threaded valves, which are designed for PVC piping and other non-threaded materials.

 

At Changsong, you'll find a wide range of ball valves. Shop for the best prices in our wide ball valve selection right now.

What are slip rings and types of slip rings？

What is a Slip Ring?

A slip ring is defined as an electromechanical device that is used to connect a stationary system to a rotating system. It is used in applications that require rotation while transmitting power or electrical signals.

 

The slip ring also is known as an electrical rotary joint, rotating electrical connector, or electrical swivel. It is used in various electrical machines to improve mechanical performance and simplify operation.

 

If a device rotates for a fixed number of revolutions. It may be possible to use a power cable with sufficient length. But it is a quite complex setup. And it is impossible if components rotate continuously. This setup is not practical and reliable for this type of application.

 

How does a Slip Ring work?

The slip rings consist of two main components; metal ring and brush contact. According to the application and design of the machine, the number of rings and brushes is decided.

 

The brushes are made up of graphite or phosphor bronze. The graphite is an economical option but the phosphor bronze has good conductivity and more wear life.

 

Depending on the RPM (rotations per minute), the brushes are fixed with rotating rings, or rings are rotating with fixed brushes. In both of these arrangements, the brushes maintain contact with the ring by pressure from the springs.

 

Generally, rings are mounted on the rotor and it is rotating. And brushes are fixed and mounted on the brush house.

 

The rings are made up of conductive metals like brass and silver. It is a mounted shaft but insulated with a center shaft. The rings are insulated from each other by nylon or plastic.

 

As the rings rotate, the electrical current is conducted through the brushes. Therefore, it makes a continuous connection between the rings (rotating system) and brushes (fixed system).

 

Types of Slip Rings

Slip rings are classified into various types according to construction and size. Types of slip rings are explained below.

 

Pancake Slip Ring

In this type of slip ring, the conductors are arranged on a flat disc. This type of concentric disc is placed in the center of a rotating shaft. The shape of this slip is flat. So, it is also known as a flat slip ring or platter slip ring.

 

It will reduce axial length. Therefore, this type of slip ring is designed for space-critical applications. This arrangement has more weight and volume. It has greater capacitance and greater brush wear.

 

Mercury Contact Slip Ring

In this type of slip ring, mercury contact is used as a conducting media. Under the normal temperature condition, it can transfer current and electrical signals by liquid metal.

 

The mercury contact slip ring features strong stability and less noise. And it provides the most scientific and economical option for applications in industries.

 

But the use of mercury creates a safety concern. Because it is a toxic substance. It is very dangerous to use this type of slip ring in applications like food manufacturing or processing and pharmaceutical. This is because it may corrupt the product if there is a mercury leakage.

 

Through Hole Slip Rings

This type of slip ring has a hole in the center of the slip ring. It is used in devices that require transmitting power or signal when need 360˚ rotating.

 

This type of slip ring is designed to install with a flange on a sleeve bracket. It has free space in the center for connecting the shaft of a machine without affecting the cable while it is rotating.

 

It has a long life span and offers low noise and maintenance. This type of slip ring is used for routing hydraulic pneumatic passages and it can integrate with high-frequency joints.

 

Ethernet Slip Ring

This type of slip ring is developed to provide reliable products that allow the transfer of the ethernet protocol through a rotary system.

 

When choosing an ethernet slip ring for communication, there are three important parameters that must be considered; Return Loss, Insertion Loss, and Crosstalk.

 

Ethernet slip rings are designed to meet the requirement of matching impedance, reducing losses, and controlling crosstalk.

 

Miniature Slip Rings

This type of slip ring is very small in size and it is designed for small devices to transfer signals or power from a rotating device.

 

Miniature slip rings are ideal for electrical devices like control panels, video transmitters, and sensors.

 

Fiber Optic Slip Ring

This type of slip ring is designed to pass signals across rotating interfaces when a large amount of data needs to transfer.

 

The fiber optic slip ring is also known as the Fiber Optic joint or Fiber-Electric Rotary joint. This type of slip ring is used in applications like; sensor signal management, HD video transmission systems, radar, and video monitoring systems, medical equipment, microwave communication, etc.

 

Wireless Slip Ring

This type of slip ring is not using carbon brushes or friction-based metal rings. As the name suggests, it can transfer data and power wirelessly. For that, it uses the electromagnetic field.

 

The electromagnetic field is produced by the coils which are placed in the rotating receiver and stationary transmitter.

 

The wireless slip ring is the best alternative for the traditional slip ring as it reduced the mechanical contacts. Therefore, it can be used in harsh environments and reduces maintenance.

 

But the only disadvantages are that the power that can be transmitted between the coil is limited. The same volume of traditional slip rings can transfer more amount of power compared to the wireless slip ring.

The History of the Rotary Joint

 

 

Throughout the 19th and early part of the 20th century, the accepted method of supplying water or steam to a rotating cylinder was through the use of stuffing boxes or packing glands, which proved inefficient. The more these sealing materials wore, the more they leaked.

 

In August of 1933, R.O. Monroe and L.D. Goff, in conjunction with a local mill, designed and built the first rotary joint. It was a device that eliminated the problems associated with stuffing boxes and packing glands and allowed the water or steam to be introduced in a much more economical method. A spring-loaded mechanical seal was used to prevent the fluid or gas medium from dispersing. The secret to the rotary joint’s mechanical success was in the seal. It allowed parts of the rotary joint to rotate with the machine, while providing a leak proof seal for the fluid or gas flowing into the cylinder.

 

During the late 1930s and into the 1940s, rotary joints became the preferred method to admit fluid or gas into a rotating cylinder. Still, there were some problems associated with installation of the rotary joints. After World War II, several innovations were applied to rotary joint design. One of these was the use of flexible metal hose, which allowed the rotary joints some flexibility in movement as the seal wore. By 1946, several updates had been incorporated into the original design, and sizes were added to better accommodate the needs of the various industries requiring rotary joints.

 

By 1954, a complete redesign of the rotary joint was underway, mainly to reduce the physical size of the unit and to better accommodate the needs of specific applications. By 1957, many industries were also concerned about increasing the efficiency of heating and cooling within rotating cylinders. Kadant Johnson began a program of researching the effects of various types of syphoning devices (both rotary and stationary), and the effects of syphon clearances on the overall heat transfer from inside the rolls to the shell.

 

In 1959, a 60" x 250" (1.5 m x 6.35 m) paper dryer was converted for testing by Kadant Johnson, and actual testing of both rotary joints and various syphoning devices began in Pensacola, Florida, USA. In 1962, a research facility was set up in Three Rivers, Michigan, USA; and in 1963, the first pictures of the inside of an operating dryer were produced on 16 mm film.

 

People involved in designing and operating machines that required rotating cylinders learned a great deal about steam condensing rates and the actions within a dryer from these first films. Rotary joint technology and syphoning technology was shared with industry.

 

Through the late 1950s and into the early 1960s, this team of researchers continued to develop new designs and gather knowledge to address the needs of general industry. The need for higher operating temperatures and speeds required that the designs of rotary joints change again. Details such as quick disconnect nipples, pressure compensators, larger sizes, and longer service life were developed.

 

Into the late 1960s and early 1970s, various new seal materials, such as plastic, Teflon™, and ceramic were also tested.

 

While the early years were focused on sealing steam and water joints, today there are thousands of configurations of standard and custom rotary joints: self-supported or externally-supported; single- and dual-flow; applications using water, air, coolant, oil, molten salt, and gas; temperatures from very low to more than 1,000° F (538° C); and speeds from 1 to 50,000 RPM.

 

We are a GHP/GHPA rotary joint supplier. Please feel free to contact us if you need them!

What is a hydraulic valve and what are the types of hydraulic valves

 

What is a hydraulic valve and what is its purpose

Hydraulic valves control the direction and flow rate of the valve. Hydraulic control valves can be divided into three types they are directional control valves, flow control valves, pressure control valves, and non-return valves. Hydraulic system uses many valves to control the flow of fluids, hydraulic valves regulates flow by cutting off, diverting, providing an overflow relief, and preventing reverse flow. Hydraulic valves are used in hydraulic power packs to direct the fluid to and from the cylinder. Hydraulic valves can be used to control the direction and amount of fluid power in a circuit. So these valves would do it by controlling the pressure and the flow rate in various sections of the circuit. System pressure can be controlled by hydraulic valves. The burden of pump pressure or temperature of the oil before the oil flow to the hydraulic circuit is reduced by using the hydraulic valve.

 

How hydraulic valves are constructed

Mostly all valves have the same structure a valve body, valve spool, and components of driven valve spool movements. Hydraulic valves are available in four types of construction and they are

 

Threaded port type

Sub-plate mounting type

Cartridge type

 

Threaded port type

These valves have threaded ports as the name says, and it is connected by piping. The piping would require space. This design can be considered as an old one so it has many disadvantages like they are prone to leakage and needs more time to fix

 

Sub-plate mounting type

 

This valve is an industrial valve, it is the same as the threaded type and the only difference can be seen in the mounting. These valves have oil ports and they can be seen in the valve’s flat surface. These oil ports are bolted to manifold at this flat surface. The oil ports would match between the holes in the manifold and oil leakage is prevented by using O-ring at each oil ports.

 

Cartridge type

 

This type of construction differs from the above types, their principle and concept are different. Cartridge type valves have better flow and response when compared to the other types. Cartridge valves are economical too.

 

What are the major requirements of hydraulic control valves

Required performance for hydraulic valves

 

Nominal pressure – it is the maximum working pressure allowed by long term reliable work of hydraulic control valve and this is limited by the valve intensity. Certain factors also influence the maximum permissible working pressure and they are reversing reliability of the reversing valve, and pressure regulation of the pressure valve. The nominal diameter is another factor, better flow capacity is achieved by good diameter so maximum flow could be achieved. Valves that have the same diameter would have different nominal flow because of their functions

 

The hydraulic valves must meet certain performance requirements and they are high sensitivity, reliability, and it must not have high noise or high vibration during the operation. Sealing should be better if the valve port is closed and if the valve port is open then the direction valve must have better core stability. High precision is needed while the operation and it must not be influenced by outside interference. These valves must be in small size and should be able to install properly.

 

What is a hydraulic proportional valve

The proportional valve can do the positioning of the spool in many ways. Due to this feature of the proportional valve infinite adjustable flow volume will be achieved by using this valve. This type of valves can be seen in hydraulic circuits that need more than one speed of actuators. These valves are capable to do the flow control of the fluid and speed of actuator and also control over the direction of the fluid flow. These valves are used in the hydraulic section where flow or pressure is needed to be varied. The proportional valves are operated by using DC power.

 

Why valves are used in hydraulic systems

In a hydraulic system, valves perform certain roles they are, control valves capable to control the operation of actuators. These valves would also regulate the pressure by controlling the oil flow. Some valves have multiple functions and are very useful an example of this would be hydraulic proportional valves.

 

What is 4 way 3 position valve and what is a hydraulic valve spool

In a four-way three-port valve there are four ports and three positions and they are manually operated hydraulic control valve. In this valve there is a liver or it can also be called a spool which can be used for the flow direction so when the liver has moved a connection is established between two ports and the flow takes place. So by changing the liver or spools position we can establish the connection between ports and control the flow direction

 

What is an electro-hydraulic valve

The electro-hydraulic valve is a hydraulic servo valve and in this valve, the servo has a device that could be a flapper nozzle or a jet pipe and this device is used to position the servo. Electro-hydraulic or servo valves are used for accurate position control. These valves are used to control hydraulic motors. These valves are very costly so while selecting this valve make sure that you need accurate position control.

 

What is a hydraulic actuator and what is its use

The hydraulic actuator can convert the fluid pressure into motion, according to the signal received. Hydraulic actuators are required when a valve operation needs a large amount of force.

 

What are the types of hydraulic valves and how does it work

In a hydraulic system, valves are used to control the pressure, volume flow rate, and direction of flow. So based on these functions hydraulic valves are classified into pressure-volume or directional control valves.

 

Directional control valves

 

These valves are used to control the flow direction of hydraulic fluid to different lines in the circuit. These valves check the connection or disconnection of pathways with relative motion between the valve core and valve body to meet the requirements of the system. There are certain types of directional control valves they are one-way valves and reversing valves. In the one way valve as the name indicates it allows flow in one direction but not reverse flow. The reversing valves change the flow direction and they cut off or connects oil channels by the relative motion of valve core in the valve body

 

Pressure control valves

 

Pressure control valves control the pressure in different segments in the circuit. The pressure is created because of some flow restriction, if this not checked then it would create many problems in hydraulic components. There are many types of pressure control valves they are pressure relief valve, pressure reducing valve, pressure sequencing valve, pressure unloading valve, and counterbalance valve.

 

Flow control valve

 

Flow control valves are used if we want to control the amount of fluid flowing past the valves. These valves are used to regulate the speed of hydraulic cylinders and motors by controlling the flow rate to the actuator. The needle valve is an example of a flow control valve. In this valve, the flow is controlled by changing the flow area of the port. The orifice can be used for flow control it is a device in the shape of a disk with a hole so the fluid will flow through the hole. This can be used as a flow meter by measuring the pressure drop across the orifice.

What's so Special About Gas Ball Valves?

 

 

Gas ball valves follow the same principles of other ball valves, they are mostly two-piece construction and feature a ¼ turn shut off. That being said, they are not your standard ball valve. Gas ball valves require CSA approval in order to be used in combustible gas applications. In this blog we will explore more about this rating, testing, and some special features of gas ball valves.

 

Ratings make all the difference

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The ratings for gas ball valves are set by CSA. There are different ratings depending on installation location (indoor vs. outdoor) and country (Canada vs. USA).

• Outdoor Gas Ratings

For a gas valve to be installed outdoors it must have CAN 3.16 approval in Canada and BRS125G approval in the USA.

• Indoor Gas Ratings

The CSA gas ratings for indoor approvals are ½ PSI and 5G. Just as it sounds, valves with these ratings can be installed indoors only. Both Canada & the USA use the same ratings for indoor valves. There are two different ratings because they have different applications, the ½ PSI rating is used for valves that are at appliances, while the 5G rating is for valves that are used in household piping systems.

 

Testing Gas Ball Valves

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Working with combustible gas is not something you want to mess around with. Gas ball valves are no exception, they are tested to 1.5 times the stated working pressure. The one exception to this is the CAN 3.16 valves because they already require a much higher pressure. Here is what pressures the valves are tested to for the different ratings:

• ½ PSI - Test Pressure 3 PSIG

• 5G - 7.5 PSIG

• CAN 3.16 125 PSI Valves - 125 PSIG

• BRS125G PSI Valves - 188 PSIG (ANSI B16.33)

• PSIG = Pounds per square inch, gauge.

It is possible for gas valves to have different pressure and temperature ratings under the same CSA approval. Valves with a higher pressure and temperature rating have been tested to the higher ratings upon request from the manufacturer. However, all the valves must have met the CSA minimum test parameters with respect to pressure and temperature as outlined in the standard.

 

Special Features

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• Yellow Handle

Most gas valves on the market have a yellow handle to signify that they have gas approvals. This is not an official fact but can be used as a quick visual indication. Always make sure that the correct approvals are on the valve before using it in a gas application.

• Pilot Tap

Some gas valves have a pilot tapping in them so a pressure gauge can be installed. This is for testing and/or monitoring the system pressure. Having a gauge right in the valve allows for the most accurate pressure to ensure the system is running at its full potential. The tapping is a standard 1/8” female pipe thread or FPT. Valves with a tapping include a 1/8” male pipe thread (MPT) plug with a tapered brass seat which makes a leak proof seal when tightened with a 3/16” Allen wrench.

 

Understanding what gas ball valve should be used for your application comes down to the ratings and where it will be going - do you need it to have ratings for indoor or outdoor use? When working with gas ball valves always consult a trained professional.

We are a industrial ball valves supplier. Please feel free to contact us if you need them!

Pneumatic & Electric Ball Valve - How They Work

 

 

Ball valves can be combined with a pneumatic actuator (pneumatic ball valves) or an electric actuator (electric ball valves) for automation and/or for controlling remotely. Depending on the application, automating with a pneumatic actuator vs an electric one may be more advantageous, or vice-versa. In this article, we will compare the two options. 

• Table of Contents
• Ball valve overview
• Actuator overview
• Pneumatic actuators
• Electric actuators
• Combining an actuator and a ball valve

 

Ball valve overview

A ball valve is a quarter-turn valve that controls the flow of a media by having a hollow rotating ball, as seen in Figure 2. The figure shows the main components of a manual ball valve in a sectional view. When the hollow portion of the ball is in line with the flow (pipe or hose), the valve is open and the media can flow through. The valve closes when the solid portion of the ball is in line with the flow, which is done with a 90-degree rotation (hence the name quarter-turn valve) of the ball.

It is also possible to position the valve between fully open and fully closed, which allows you to regulate the flow more precisely. Typical ball valves have two ports, one for an inlet and one for an outlet. However, three ports (L or T) are also available, and depending on how the valve is assembled and installed will determine how the 90-degree rotation of the ball directs the media flow. Four-port ball valves are possible but rare.

Ball valves have a valve stem, which is attached to the ball and controls its rotation. In Figure 2, the valve stem is connected to a manual handle to actuate the valve. However, the valve stem can also be connected to a pneumatic or electric rotary actuator to spin the stem to open and/or close the ball valve automatically and/or remotely.

 

Actuator overview

A valve actuator is a device that is used to remotely control a valve. If it controls a quarter-turn valve, the actuator is known as a quarter-turn actuator. Instead of a manual lever, you can mount an actuator on the valve to automatically and/or remotely control it. Actuators use a power source to generate the torque that is required to operate (rotate) a ball valve. For most actuators, the power source is either pneumatic, electric, or hydraulic (not discussed in this article). The difference in this power source makes different designs, which each have different advantages and disadvantages for certain applications (discussed below). Aside from the torque generating component, an actuator may have other features such as position indicators and manual override.

 

Pneumatic actuators

Pneumatic actuators control ball valves by the conversion of compressed air energy to mechanical motion. A rotary mechanical motion is required in a ball valve for a 90 degrees turn. Pneumatic actuator ball valves can be single-acting or double-acting. A single-acting pneumatic actuator uses a single compressed air input to turn the valve and a spring to return the valve to the normal position. A double-acting pneumatic actuator has two compressed air inputs to turn the valve and return the valve to the original position.

 

Operating principle

The most common mechanism for a pneumatic actuator for ball valves is the rack and pinion mechanism. This comprises of the rack (a linear gear) and the pinion (a circular gear) (figure 4). The rack is attached to a piston which is pushed by compressed air to achieve linear motion. This linear motion is converted to circular motion by the pinion. The pinion drives the stem of a ball valve to open and close positions.

To control the pneumatic actuator for ball valves, the compressed air is regulated by solenoid valves. Electrical signals from the controller energize the solenoid valve to either open or close positions allowing compressed air to flow through to both piston sides of the pneumatic actuator. The piston pushes the rack which turns the pinion connected to the stem of the ball valve.

 

 

Electric actuators

Electric actuators convert electrical energy into rotary force by the use of an electric motor to turn the ball valve through 90 degrees. They are energy-efficient, clean, and a quiet method of valve control. The electric motor can be powered by an alternating current (AC) or a direct current (DC). It is housed in a robust, compact housing that also contains other components of the actuator such as gearings, limit switches, wiring, etc. The whole assembly is connected to a valve through a compatible connection interface.

 

Operating principle

The electric motor generates a torque, which is transmitted by a shaft connected to the valve stem. This rotates the ball valve. To achieve the required torque, a system of gears is connected to the electric motor shaft. The torque capacity is an important specification for selecting an actuator. It must be higher than the required torque (breakaway torque) to turn the ball valve by a certain percentage often specified by the ball valve manufacturer. The breakaway torque is the minimum torque required to turn the ball valve usually in the fully closed or fully open static positions.

The speed of operation (the response time) of an electric actuator is inversely proportional to the torque of the actuator. The gear system defines the relationship between speed and torque. A higher gear ratio would result in more torque but a lower response time.

Electric actuators can be powered from a 12, 24, and 48V direct current and 24, 48, 120, 130, and 240V alternating current. Limit switches are installed to stop the current to the motor when fully closed and open. Electric motors can be used to carry out modulating control. This is used to accurately position the valve at any point between fully opened and fully closed positions (i.e. between 0° and 90°). This is useful for regulating the flow rate through the valve. A positioning circuit board (PCB) is installed in the electric actuator to modulate the electric motor. 

 

Combining an actuator and a ball valve

Although actuators and ball valves are separate components, they are most often used together. Therefore, it is more convenient to get them as a package to ensure conformity. Combining an actuator with a ball valve gives you an automatic ball valve that can be controlled remotely. The actuator and the ball valve have a connection interface to connect them. The connection interface comprises of a shaft, or stem, to connect the valve ball, and a flange to bolt the actuator to the valve. This interface may be brand-specific or standardized to standards. You can mount a brand-specific actuator on a compatible brand-specific valve. On the other hand, different ball valves and actuators can be interchanged as long as they follow the same standard.

 

Comparison between pneumatic and electric ball valves

The following are some of the comparable features of pneumatic and electric ball valves:

1) Rotation speed
The rotation speed is the speed at which the ball of an actuated ball valve makes a complete rotation (90-degrees). Typically for the same size units, the rotation speed of an electric ball valve is lower than that of a pneumatic ball valve.

2) Life span
The life span of equipment is the time that the unit is fully functional and operational. Pneumatic ball valves have fewer components and are easier to maintain; hence they have a longer life span than their electric counterparts. Electric actuators have several components that need maintenance, like the electric coil, electronic driver, mechanical actuator, etc.

3) Precision
Precision, or modulation, is for units that stop at a partially open point (i.e. 20-degrees open) to more accurately regulate the flow. Both pneumatic and electric actuators are precise in operation, but motorized ball valves have higher levels of precision. An electric ball valve is capable of opening and closing by very precise degrees. Pneumatic actuators carry out modulation by controlling the air pressure at the inlet port. Leaks or pressure fluctuations can easily affect the valve’s position. Electrical actuators, on the other hand, use exact electrical control signals to carry out control. Additional information can be found in our electrical modulating ball and butterfly valves article.

4) Energy consumption
Energy consumption is the energy required by the actuator to rotate the valve. In comparison, the energy consumption of an electric operated ball valve is less than pneumatic actuated ball valves. In pneumatic actuators, the entire air compression system (compressor, filters, lubricators, power, etc.) accounts for their high energy consumption.

5) Fail-safe
This is a safety feature designed to automatically open or close a valve in case of a power failure. It is typically easier and cheaper to feature a fail-safe mechanism on a pneumatic ball valve than on a motor actuated ball valve. Pneumatic acting actuators are very common and make use of a spring to return to the base position and are ideal as a fail-safe solution. Electric actuators with a fail-safe mechanism can operate with a battery or a spring and are usually more expensive than the pneumatic solution.

6) Cost
The cost of a pneumatic ball valve is usually lower than an electric one because the actuator design is less complex. However, this doesn’t take into account the costs of the components of the pneumatic system, such as the compressor, air preparation, pipes, etc. When no pneumatic system is available near the valve, usually electric actuation is preferred. The operation of a pneumatic valve is more expensive in the long run due to the higher energy consumption and energy losses that are a result of generating compressed air.

7) Position feedback
Position indicators indicate the position of the actuator at any given time. They are usually placed atop the actuator for high visibility. Most pneumatic actuators can be equipped with a limit switch on top for electrical feedback. Many electrical actuators have internal limit switches for position feedback. However, more basic actuators do not have this feature.

8) Size/torque range
Torque is the rotary force a ball valve requires to turn. Pneumatic actuators offer a much higher torque per unit size than electric actuators. Therefore, for applications requiring a large valve or high torque typically a pneumatic ball valve is a better option.

9) Hazardous conditions
An electric ball valve has to be NEMA/ATEX certified before it can operate in hazardous conditions. Pneumatic actuators, however, are more widely available with ATEX certification. Also, they neither generate nor are affected by electromagnetic disturbance. Unlike their electric counterparts, pneumatic actuators are not sensitive to wet environments, neither are they subject to overheating.

The Ultimate Guide to Select Swivel Joints

 

 

What is a Swivel Joint?

Swivel joints, also known as rotary unions are used in applications where a constant transmission of fluids from a stationary source to a rotating source is required without cross-contamination or leakage. Typical applications use swivel joints to allow for 360-degree rotation while preserving hoses from getting tangles as components turn. In return, mechanical stresses that would result from hose twisting, bending, and stretching can be relieved.

Swivel joints are engineered to operate at a wide range of pressure and temperature for a variety of conditions and environments. Based on industry requirements, the swivel joint can be designed to have multiple passages and can transfer different types of fluid simultaneously at various rotational speeds. Typically, as the number of passages increases, the size increases, and speed will be lower.

 

How Does a Swivel Joint Work?

Swivel Joints come in different shapes and sizes based on the application and the environment where it is subjected to. While design consideration should be given to external factors, all the swivel joints have two main components: a shaft and housing.

The concept behind a swivel allows the shaft to rotate while the housing remains stationary in position. The shaft has drilled holes of varying size and depth starting from its top surface. Variable hole depths and markings define the flow path of fluid within the swivel. Through internal design, the fluid is carried through the shaft into and out of the swivel joint.

The housing unit includes machined passage and grooves to facilitate fluid transfer within the swivel and preventing cross leaks. Numbered markings are found on the housing outer diameter surface and the same can be found on the top surface of the shaft.

These numbers define where a user would expect the fluid to flow in/out between shaft and housing through the machined internal passages. A series of carefully selected internal components are fitted between the shaft and housing at specified locations. These include seals, snaps rings, O rings, wearings, small bearings in certain applications.

The selection of internal components is of vital importance while designing a swivel joint as extreme attention has to be given to the tolerances and internal design of the housing grooves. Failure to adhere to the recommended design and machining requirements results in leaking components.

Passage of power and signals are sometimes required for particular applications and industries. Slip rings can be integrated with the swivel joint through passing electric cables within the hollow inner diameter of the shaft.

 

How to Select a Swivel Joint?

As opposed to other rotary components in the same industries, a swivel joint mostly endures internal loads while operational. This is a direct result of pressurized fluid flowing within its internal components. To select an appropriate swivel joint, multiple influencing factors must be considered.

The most influencing factor on a swivel joint is the internal sealing solution between the shaft and housing. Very precise tolerances must be maintained during the machining phase to create the required grooves for seals and internal components to be fit.

Seals, o-rings, wear rings, and bearings are inserted within these internal grooves and must be able to withstand the pressures induced by the fluid Swivel joints are rated by the manufacturer as to their recommended operating pressures, temperatures, and speeds.

These values are directly related to the internal components specifications, geometric machining tolerances, and type of fluid used significant design and space considerations must be given for a swivel joint and its ports.

Based on application requirements, a swivel joint may have up to 9 different ports to supply fluid through different passages. A higher number of passageways result in significant size and material increase.  

Swivel joints can be modified in size and port sizes with respect to application requirements. Space restrictions, load requirements, duty cycle, and environmental surroundings all factors that are considered while selecting an appropriate component

Based on the requirement provided Slewmaster will be able to provide the best solution that suits the application.

In most cases, our standard in-stock swivels can be modified to fit into your application, and if required Slewmaster can provide a custom-built swivel that suits your needs. Further, Slewmaster can also cross-reference other manufacturers' Swivel Joint and provide an equivalent solution.

 

What are the Different Applications That Use Swivel Joints?

Due to a wide range of custom modifications that can be applied on a swivel joint, it can be found across many applications. Vacuum trucks and cranes that require their booms to rotate 360 degrees using a slew drive run into the problem of hose bending and tangling.

Introducing swivel joints to the system creates a smooth fluid flow for continuous rotation. Bottling lines use swivel joints to deliver fluid across to the different end locations. Design considerations are given to the different fluid viscosities to determine operating pressure requirements.

Farming and agricultural equipment utilize swivel joints in several ways including herd feeding and waste recycling. Welding and robotic arms often require electric passage and slip rings are used to allow for mobility and electric transmission.

 

How is a Swivel Joint Mounted?

Inspect the swivel joints and make sure that all the connections and passages are clean and free from any physical damage during shipment.

A flexible connection/ hose should always be used while installing a Swivel joint. While mounting the Swivel Joint, ensure that either shaft or housing are mounted in a manner that allows for some movement in order to accommodate any misalignment or run-out during rotation. It is recommended to fasten an anti-rotation arm to the stationary part of the rotary union.

When mounting the shaft and the housing make sure that pipe thread sealant is used on fittings and the fitting is properly tightened. For proper functioning of a swivel, it is required to ensure that the mounting flange or surface should be concentric to the axis of the swivel assembly.

After all, fittings are installed bolt the assembly down using the mounting flange or tapped holes provided on the swivel joint. It is recommended to perform a dry run after the swivel is installed to ensure proper mounting of the swivel joint assembly and to verify that there is an unintended movement of the swivel joint due to misalignment.

High pressure selected seals and internal components contain the fluid from leaking out of the closed system. If any leakage is found around any surfaces of the swivel joint, the manufacturer must be alerted immediately.