Butterfly Valves Used in Industrial and Commercial Applications

Automated butterfly control valve.
(Valtek)

Industrial process control valves are available in uncountable combinations of materials, types, and configurations. An initial step of the selection procedure for a valve application should be choosing the valve type, thus narrowing the selection field to a more manageable level. Valve "types" can generally be classified by the closing mechanism of the valve.

A butterfly valve is used for stopping or controlling flow of liquids or materials through pipes. The "butterfly" refers to the round, flat disk that allows for flow through the valve. Butterfly valves are a member of the "quarter-turn" valve family, meaning fully open to fully closed in 90 degrees rotation. They are opened and closed via a lever, manual gear operator, pneumatic actuator, or electric actuator. Butterfly valves can be used for on-off service and some varieties are used as control valves. Butterfly valves are generally less expensive than other high flow valves, lighter in weight, and take up less piping length. Since the disk is always in the flow path, butterfly valves always have a pressure drop across the valve.

There are two primary types of butterfly classifications:

1. So called "rubber lined" butterfly valves (resilient seated) which are best suited for lower pressure, lower temperature, general purpose applications.
2. High Performance Butterfly Valves (HPBV) which are designed to ANSI pressure classifications and are suited for more robust industrial applications.

Rubber lined butterfly valve.
(Centerline)

Rubber lined (resilient seated) butterfly valves come in a variety of seating materials, where the disk "jams" in to the seat. This provides a tight closure, but also causes wear on the seat. Seat replacement is part of normal maintenance on these valves. Another characteristic of rubber lined butterfly valves are higher starting and ending torques due to the "jamming" and "unjamming" of the disk in the seat.

High performance butterfly valves have precision machined teflon, or metal seats, and are slightly offset as to lessen the amount of seat-to-disk interference. The disc still is pushed against he seat, but in a much more controlled and measured manner. Seat wear is still an issue, but not like rubber lined valves. Seating and unseating torque effects are much less as well.

Triple offset butterfly.
(Valtek)

A variation of the HPBV is the triple eccentric butterfly valve which uses a metal seat and a "triple-offset" design, best described as the disk coming "off and away" from the seat. This assures that the disk only contacts the seat at time of full closure, reducing wear on the metal seat. These valves provide excellent shut off in critical applications.

Butterfly valves come in three body styles:

1. Wafer body, whereby the valve is "sandwiched" and held in place between two pipe flanges and are suitable for lower pressure applications.
2. Lug style bodies that have threaded "lugs" cast in to the body of the valve and bolts are used to secure the valve for end of line service or keeping the valve in place when the piping is disassembled.
3. ASME flanged butterfly valves where the valve body is in-between two ASME flanges.

Butterfly valves, like other valve types, have applications where selection and design of one style outperforms another style. Careful consideration and consultation with a valve expert is a first step toward making a good selection. Combine your process know-how with the product application expertise of a professional sales engineer to produce the best solutions to your process control challenges.

Flowserve Valtek MaxFlo 4 Eccentric Rotary Plug Control Valve

The Flowserve Valtek MaxFlo 4 control valve is a high performance eccentric rotary plug valve designed for the process industry. It features a large capacity, standard hardened trim and superior shaft blow-out protection.

This valve is available in sizes 1 through 12 inches, ASME Class 150, 300 and 600 as well as DIN PN 10, PN16, PN 25, PN40 and PN63. An optional ISA 75.08.01 or DIN EN 558 series 1 long-pattern body makes this valve an easy drop-in replacement for a globe control valve. 

Founded in 1960, Swanson Flo has long maintained our position as an industry leader in process automation with unmatched project success leveraging industry preferred products and services. 

https://www.swansonflo.com 

800-288-7926

Worm Gear Valve Operators

Worm gear operator (WedgeRock)

Every industrial valve needs a means to open and close, allowing the process to flow.  Worm gear actuators provide a mechanical advantage to make hand operation possible for most quarter-turn butterfly, ball, and plug valves as well as quarter-turn and multi-turn dampers. Gears provide mechanical advantage to an operator providing the force required to open and close the valve.  Torque can be increased or decreased by changing the size of the hand wheel. Manual worm gear operators are relatively inexpensive and require little involvement beyond their in the process line.

Download the WedgeRock RW Series IOM PDF here.

WedgeRock RW Worm Gear Actuator IOM from Swanson Flo

Understanding Biofuels

Ethanol Plant

Unlike other renewable energy sources, biomass can be converted directly into liquid fuels, called "biofuels," to help meet transportation fuel needs. The two most common types of biofuels in use today are ethanol and biodiesel. Ethanol is an alcohol, the same as in beer and wine (although ethanol used as a fuel is modified to make it undrinkable). It is most commonly made by fermenting any biomass high in carbohydrates through a process similar to beer brewing. Today, ethanol is made from starches and sugars, but scientists are developing technology to allow it to be made from cellulose and hemicellulose, the fibrous material that makes up the bulk of most plant matter.

Ethanol can also be produced by a process called gasification. Gasification systems use high temperatures and a low-oxygen environment to convert biomass into synthesis gas, a mixture of hydrogen and carbon monoxide. The synthesis gas, or "syngas," can then be chemically converted into ethanol and other fuels.

Ethanol is mostly used as blending agent with gasoline to increase octane and cut down carbon monoxide and other smog-causing emissions. Some vehicles, called Flexible Fuel Vehicles, are designed to run on E85, an alternative fuel with much higher ethanol content than regular gasoline.

Biodiesel is made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled cooking grease. It can be used as an additive (typically 20%) to reduce vehicle emissions or in its pure form as a renewable alternative fuel for diesel engines. Research into the production of liquid transportation fuels from microscopic algae, or microalgae, is reemerging. These microorganisms use the sun's energy to combine carbon dioxide with water to create biomass more efficiently and rapidly than terrestrial plants. Oil-rich microalgae strains are capable of producing the feedstock for a number of transportation fuels—biodiesel, "green" diesel and gasoline, and jet fuel—while mitigating the effects of carbon dioxide released from sources such as power plants.

Swanson Flo, and its subsidiary BioFuels Automation, has decades of experience in the renewable fuels industry. Their team is responsible for the products in over 90% of plants nationwide and are uniquely positioned to keep the existing bio-refineries operational while minimizing downtime. For more information about the processing of renewable fuels, contact Swanson Flo by calling 800-288-7926 or visiting https://www.swansonflo.com.

Happy New Year from Swanson Flo

With 2017 coming to a close, all of us at Swanson Flo wanted to reach out and send our best wishes to our customers, our vendors, and our friends! We hope that 2018 holds success and good fortune for all of you.

Industrial Valve Actuators: An Overview

Pneumatic Actuator
(Limitorque)

Valves are essential to industries which constitute the backbone of the modern world. The prevalence of valves in engineering, mechanics, and science demands that each individual valve performs to a certain standard. Just as the valve itself is a key component of a larger system, the valve actuator is as important to the valve as the valve is to the industry in which it functions. Actuators are powered mechanisms that position valves between open and closed states; the actuators are controllable either by manual control or as part of an automated control loop, where the actuator responds to a remote control signal. Depending on the valve and actuator combination, valves of different types can be closed, fully open, or somewhere in-between. Current actuation technology allows for remote indication of valve position, as well as other diagnostic and operational information. Regardless of its source of power, be it electric, hydraulic, pneumatic, or another, all actuators produce either linear or rotary motion under the command of a control source.

Thanks to actuators, multiple valves can be controlled in a process system in a coordinated fashion; imagine if, in a large industrial environment, engineers had to physically adjust every valve via a hand wheel or lever! While that manual arrangement may create jobs, it is, unfortunately, completely impractical from a logistical and economic perspective. Actuators enable automation to be applied to valve operation.

Electric Actuator
(Limitorque)

Pneumatic actuators utilize air pressure as the motive force which changes the position of a valve. Pressurized-liquid reliant devices are known as hydraulic actuators. Electric actuators, either motor driven or solenoid operated, rely on electric power to drive the valve trim into position. With controllers constantly monitoring a process, evaluating inputs, changes in valve position can be remotely controlled to provide the needed response to maintain the desired process condition.

Large butterfly valve with actuator.

Manual operation and regulation of valves is becoming less prevalent as automation continues to gain traction throughout every industry. Valve actuators serve as the interface between the control intelligence and the physical movement of the valve. The timeliness and automation advantages of the valve actuators also serve as an immense help in risk mitigation, where, as long as the system is functioning correctly, critical calamities in either environmental conditions or to a facility can be pre-empted and quickly prevented. Generally speaking, manual actuators rely on hand operation of levers, gears, or wheels, but valves which are frequently changed (or which exist in remote areas) benefit from an automatic actuator with an external power source for a myriad of practical reasons, most pressingly being located in an area mostly impractical for manual operation or complicated by hazardous conditions.

Thanks to their versatility and stratified uses, actuators serve as industrial keystones to, arguably, one of the most important control elements of industries around the world. Just as industries are the backbones of societies, valves are key building blocks to industrial processes, with actuators as an invaluable device ensuring both safe and precise operation.

Visual Demonstration of Cavitation and its Adverse Effects on Control Valves and Pumps

Fluid passing through a control valve experiences changes in velocity as it enters the narrow constriction of the valve trim (increasing velocity) then enters the widening area of the valve body downstream of the trim (decreasing velocity). These changes in velocity result in the fluid molecules’ kinetic energies changing as well. In order that energy be conserved in a moving fluid stream, any increase in kinetic energy due to increased velocity must be accompanied by a complementary decrease in potential energy, usually in the form of fluid pressure. This means the fluid’s pressure will fall at the point of maximum constriction in the valve (the vena contracta, at the point where the trim throttles the flow) and rise again (or recover) downstream of the trim:

If fluid being throttled is a liquid, and the pressure at the vena contracta is less than the vapor pressure of that liquid at the flowing temperature, the liquid will spontaneously boil. This is the phenomenon of flashing. If, however, the pressure recovers to a point greater than the vapor pressure of the liquid, the vapor will re-condense back into liquid again. This is called cavitation.

As destructive as flashing is to a control valve, cavitation is worse. When vapor bubbles re-condense into liquid they often do so asymmetrically, one side of the bubble collapsing before the rest of the bubble. This has the effect of translating the kinetic energy of the bubble’s collapse into a high-speed “jet” of liquid in the direction of the asymmetrical collapse. These liquid “microjets” have been experimentally measured at speeds up to 100 meters per second (over 320 feet per second). What is more, the pressure applied to the surface of control valve components in the path of these microjets is intense. Each microjet strikes the valve component surface over a very small surface area, resulting in a very high pressure (P = F/A ) applied to that small area. Pressure estimates as high as 1500 newtons per square millimeter (1.5 giga-pascals, or about 220000 PSI!) have been calculated for cavitating control valve applications involving water.