Control Valve Positioner and Control Valve Actuator Basics

Control Valve Loop*

Control valves control fluid in a pipe by varying the orifice size through which the fluid flows. Control valves contain three major components, the valve body, the positioner, and the valve actuator.

The valve body provides the fluid connections and movable restrictor comprised a valve stem and plug that is in contact with the fluid that varies the flow.

The valve actuator is the component that physically moves the restrictor to vary the fluid flow.

Their are two general categories of control valves - linear and rotary. Three actuator types are used in linear control valves including spring and diaphragm, solenoid, and motor operated. Three actuator types are used in rotary control valves including pneumatic, electric, and electro-hydraulic. Rotary actuators are sometimes referred to as "quarter-turn" or "partial-turn".

Pneumatic positioner with
rotary vane actuator
on ball valve.

The valve disc (restrictor) controls flow through the valve body. A positioner receives information from a supervisory controller advising wether or not the flow condition is satisfactory. The positioner then provides a signal to the actuator that provides the force to open and close the valve.

Each type of positioner works in response to a process signal. Some positioners (linear) use a 3-15 PSI pneumatic process signal. The pressure is exerted on a large diaphragm creating downward force that is applied against a spring which moves the restrictor up and own. Other types of positioners use a 3-15 PSI pneumatic signal to regulate a higher supply pressure (such as 0-60 PSI) to move pistons or vanes back and forth (rotary). 

The variable 3-15 PSI control signal can be provided directly by a pneumatic controller connected directly to the process, or in other cases the 3-15 PSI is regulated by an electropneumatic device called an I/P or E/P (current to pressure or voltage to pressure) transmitter. These transmitters receive their signal from a supervisory control as a 0-10VDC or 4-20mA and then throttle the 3-15 PSI output to open/close the valve. 

* Image courtesy of Tony R. Kuphaldt from "Lessons In Industrial Instrumentation"

Pneumatic Actuators that Stand Up to Pulp and Paper Plants

Simplified Pulp and Paper Process Diagram

The "kraft process" (also known as the sulfate process) is the method to convert wood chips into pulp and then to cellulose fibers. This is done by mixing the wood chips with sodium hydroxide and sodium sulphate, soaking, cooking and processing. One reason why the kraft process dominates the paper industry is because of the ability of the kraft chemical recovery process to recover approximately 95 percent of the pulping chemicals and at the same time produce energy in the form of steam.

The purpose of the chemical recovery cycle is to recover cooking liquor chemicals from spent cooking liquor. The process involves concentrating black liquor, combusting organic compounds, reducing inorganic compounds, and reconstituting cooking liquor.

Chemical recovery process flow diagram.

Green liquor is created when molten inorganic salts, referred to as "smelt," collect in a char bed at the bottom of the furnace. Smelt is drawn off and  dissolved in weak wash water to form a solution of carbonate salts - known as green liquor - which is primarily Na2S and Na2CO3. Green liquor also contains insoluble unburned carbon and inorganic Impurities, called dregs, which are removed in a series of clarification tanks.

Decanted green liquor is transferred to the causticizing area, where the Na2CO3 is converted to NaOH by the addition of lime (calcium oxide [Ca0]). The green liquor is first transferred to a slaker tank, where Ca0 from the lime kiln reacts with water to form calcium hydroxide (Ca(OH)2). From the slake, liquor flows through a series of agitated tanks, referred to as causticizers, that allow the causticizing reaction to go to completion (i.e., Ca(OH)2 reacts with Na2CO3 to form NaOH and CaCO3).

On the right you see a Kinetrol model 14 double acting actuator on a 8” full-port ball valve on a green liquor line. The valve cycles 2 times per day to direct green liquor flow and weak wash (weak white liquor) alternatively from one pipe to another in order to prevent solids build up in the pipelines.

Equipment used to produce pulp, paper, and paperboard is exposed to a wide range of temperature and humidity conditions, and contaminants. Actuators used in Pulp and Paper manufacturing processes must withstand the most difficult operating conditions.  Kinetrol actuators are preferred in these situations because they don't allow corrosive atmospheres to penetrate the actuator or springs, their long cycle life,  and their epoxy stove enamel finish.

Contact the experts at Kinetrol USA at 972-447-9443 to discuss any pulp and paper mill actuator application.

New Blueline Section on Kinetrol USA Website

The Blueline Series actuators and spring return units with food grade coating have been added to the KinetrolUSA.com website.

More information can be found here - http://www.kinetrolusa.com/blueline.

PROCESS EXPO 2017 Free Pass Courtesy of Kinetrol

Get a free pass to the PROCESS EXPO 2017 courtesy of Kinetrol USA!

September 19–22, 2017 • McCormick Place • Chicago, IL USA 

PROCESS EXPO is the nation’s largest trade show dedicated to bringing the latest technology and integrated solutions to all segments of the food and beverage industry.

Kinetrol is featuring the new Blueline Actuator series specifically for the food and beverage industry. Kinetrol Blueline Rotary Vane Actuators provide a superior alternative for actuating quarter-turn valves in food and beverage applications and are guaranteed for up to 4 million operations.

Stop by the Kinetrol booth #2670 and see the difference!

Instructions for your free pass: Visit this link and fill in your information. Or, go to the PROCESS EXPO 2017 site and use code 74768 when registering.

Kinetrol PROCESS EXPO 2017 Invitation from Kinetrol USA

The Role of Industrial Valve Actuators

Kinetrol pneumatic actuators installed on pipeline.
Valves are essential to industry. Valve automation refers to
the electric, pneumatic, or hydraulic systems deployed to
open, close or position the valve.

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.

Pneumatic vane actuator
with spring return and positioner
on plastic body valve.

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.

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.

Pneumatic Vane Actuators Can Now Be Used in Foodservice Wash-down Applications

Kinetrol Blueline Foodservice Actuator
(Double-acting)

Finally, food and beverage processing companies can take advantage of the long-life and headache-free performance of Kinetrol vane actuators.

Kinetrol USA has officially introduced it's "Blueline" Series of pneumatic vane actuators for use in foodservice and beverage processing. The actuators are intended to be installed in areas where harsh chemical wash-down is required. These areas are very tough on most types of pneumatic actuators because the caustic or acidic chemicals used in cleaning adversely effect the actuator. All stainless steel actuators are an alternative, but they are prohibitively expensive. Kinetrol's Blueline Series provides a very economical option.

Kinetrol Blueline Actuator
(Spring-return)

Blueline Actuators are permitted for use in contact with food in compliance with the Federal Food, Drug and Cosmetic Act (FDA) and all applicable regulations, including 21 CR 175.300 (Code of Federal Regulations). The new actuator has an applied coating that meets with the FDA's allowance whereby "Resinous and polymeric coatings may be safely used as the food-contact surface of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food ...".

The Blueline Series provides food and beverage processors all the time-proven benefits of the Kinetrol PLUS provides an affordable option for tough chemical wash-down areas. 

Kinetrol Blueline Features:

• Very good resistance to "caustic wash-down" procedures as typically performed in the food industry.
• Very good resistance to corrosion In salt laden environments.
• Very good non-stick properties.

For more information, contact Kinetrol at 972-447-9443.

Rotary Vane Actuators for Corrosive Marine Environments: The Right Choice

Corrosive marine environments present problems for
valve actuators.

Corrosive marine environments such as offshore oil rigs, shipyards, and maritime facilities present special challenges for pneumatic actuators. Proper selection of actuator design is important for long, trouble-free life. Salt-laden dust and high humidity take a harsh toll on the internal and external parts of any industrial equipment if not properly designed and protected. For example, rack & pinion and scotch-yoke actuators are particularly susceptible because of the relative ease of penetrating the actuator and affecting their critical components, such as metallic gears and coil springs. Spring-return rack & pinion and scotch-yoke actuators further complicate the issue because they require the intake and venting of ambient air, along with any contaminants in the air.

Rotary vane actuators, (such as Kinetrol) provide strong immunity to internal corrosion. First, they have no internal gears or springs to corrode. Second, the internal surfaces are coated with a very durable, epoxy enamel finish and all internal hardware is made from stainless steel. Additionally, the “wiping” action of the vane and lip-seals provide a self-cleaning effect that prevents corrosion in the working areas. Finally, unlike rack & pinion and scotch-yoke actuators whose coil springs are bathed in ambient air, (Kinetrol) vane actuators use externally mounted clock type springs that are 100% sealed from ambient air/gasses and are unaffected by corrosive atmospheres.

For any application where corrosion is a problem, such as those in offshore platforms or other marine facilities, engineers should strongly consider rotary vane actuators as the preferred choice for any quarter-turn valve application.

The video below illustrates the difference in construction in actuator types and illustrates the inherent advantages of vane style actuators:

Kinetrol FDA Approved Coating

Kinetrol actuator with
FDA approved coating

Products coated with Kinetrol RAL5002 Blueline food grade paint option, have a Kinetrol Variation Product Code: BU. This is suitable for use in the European Union & United States of America for Standard Actuators & Spring Units. For other assemblies including ULS and XLS switchboxes, AP, P3 and EL positioners a special order code will be issued.

For Example: a model 09 ISO Double acting Actuator having this coating would be: 094-100BU or model 09 ANSI Spring Return Actuator clockwise would be 097-120BU.

The product casings are pretreated prior to coating for additional protection. This coating system exhibits the following characteristics:

1. Good resistance to 'caustic washdown' procedures as typically performed in the food industry. 
2. It shows exceptional resistance to chipping/flaking. It does not 'chip' in a brittle manner but remains attached to the substrate. 
3. If in extreme circumstances, the coating becomes dislodged from the product surface, its color is particularly visible to the human eye or sorters/sensors/detectors. 
4. Good resistance to corrosion in salt laden environments. 5. The coating has good non-stick properties. 

Coating Statement for United States of America:

Kinetrol Blueline coating
now FDA approved.

This coating is permitted for use in contact with food in compliance with the Federal Food, Drug and Cosmetic Act (FDA) and all applicable regulations, including 21 CR 175.300 (Code of Federal Regulations).

Coating Statement for European Union:

When coated in this finish, Kinetrol product casings meet the requirements of German BfR L1 for Temperature Resistant Polymer Coating Systems for Frying, Cooking and Baking Utensils. BfR recognizes that when in contact with food it will not transfer its constituents in quantities that could endanger human health. 

For more information on using Kinetrol actuators in food and pharmaceutical applications contact Kinetrol USA at www.kinetrolusa.com or call 972-447-9443.

Cement Silos Need Valve Actuators with Power and Reliability

Kinetrol spring return actuator on cement silo valve.

A silo is a structure for storing bulk materials. The cement silo is an integral piece of equipment for any concrete production operation as it allows the product to be stored, purchased and distributed in bulk. Fitted beneath silos, various types of butterfly or other rotary valves are used to control the flow of cement into trucks or other transport devices.

One particular cement processing plant needed a replacement for their main silo off loading valves. These valves fill cement trucks the company used to deliver their product.

The plant's existing valves were poorly applied for this use and were causing major headaches. The valves were designed with thin steel plate, large gaps between the valve body and disc, and rubber seals that wore away, leading to cement leaking through the valve. The leaking cement would spill onto a feed trough where it would cake and require manual cleaning - an expensive and time consuming operation. If the valve didn’t leak, this expense and time would be saved.

A custom valve manufacturer was called in to use their engineering and fabrication expertise to develop a custom valve that would last. The result was a new rotary valve that uses a much hardier wear plate, and the rotor and body are carefully machined with only a 2/100ths of an inch gap between them. Additionally, the design provides a mechanism to catch any cement should any ever make it through the gap.

The new, custom designed valve needed an actuator that would be equally reliable. The selection of Kinetrol vane actuator with a spring return was the most obvious because its power and its reliability. With only one moving part and no complex linkage to wear out, it was the best choice for long life. The combination of valve and actuator is expected to last many thousands of operations with no maintenance.

Procedure for Calculating Distance of Actuator from Hot Valve

The purpose of this post is to assist in determining the proper distance of a Kinetrol actuator from a hot valve.

In many situation, valves are put inline with a hot process media flowing through the piping system. In these situations, careful consideration must be taken to avoid over temperature exposure of the Kinetrol actuator via conductive or radiant heat.

The following formulae will assist in giving you data to calculate the safe distance between hot valve and actuator.

For steel RHS mount kits, standard (80°C Max.) actuators In ambient 50°C air. 

If you need assistance, or have any concerns about properly distancing the actuator from your process, it's always best to consult with the experts at Kinetrol USA. They're just a phone call away. For more information visit www.kinetrolusa.com or call 972-447-9443.

Kinetrol + Plug Valve = Optimum Sludge Valve Performance

Water treatment plant

Sewage sludge is the semi-solid material that is produced during sewage treatment of industrial or municipal wastewater. Sludge blowdown valves are used in water and wastewater treatment systems that separate solids prior to filtration. These valves are particularly susceptible to fouling and ultimately prone to failure.

Many valve manufacturers specify high-pressure/high-torque actuators to overcome the sludge. Many times they choose linear type valves and screw-type linear actuators because they provide the brute force needed to push through the sludge. An unwanted side-effect of using linear valves and actuators is that the same force used to push the disc through the sludge, also causes valve damage by pushing and grinding solids into the valve seats, disc and seals. Eventually, the valve becomes so damaged it no longer provides proper shut-off.

Kinetrol actuator

Pneumatic scotch yoke and rack and pinion actuators, with quarter-turn valves, can provide the torque required for opening and closing the valve, and the nature of some quarter-turn valve designs protect internal parts from damage. Plug valves are designed this way and when combined with double acting pneumatic actuators that operate on a controlled time frequency, are a very reliable design for this application. The cycle frequency depends on the amount of solids in the media, and cycle times of opening and closing every 20 minutes are common. This cycle rate however, is problematic for scotch yoke and rack and pinion actuators, causing them to fail prematurely. In some cases the actuators fail in only 3 - 4 months of use.

For sludge applications, Kinetrol rotary vane actuators mounted on quarter-turn plug valves are a great choice . The combination of the high cycle actuator design, with the design benefits of a plug valve, offer wastewater treatment operators a valve assembly that will provide years of trouble-free life.

Short Kinetrol Actuator Application Video

Here's a brief video of Kinetrol actuators applications.

Warehouse Palletizers Rely on Kinetrol Actuators for Trouble-free Performance

Palletizer gripper head with
Kinetrol actuator

In today’s highly automated fulfillment centers, distribution centers, and warehouse automation operations, fast, efficient and reliable packaging automation is the key to the company’s success. Complete packaging systems seamlessly connect an array of subsystems to form a cohesive, highly optimized, accurate packaging automation operation.

Palletizer with Kinetrol Actuators

One component is the palletizer subsystem. The palletizer subsystem provides automatic stacking of products on top of a pallet.

More sophisticated palletizers have complex control systems to provide the speed, accuracy and control required for large scale operation. The control systems are made up of computers, PLCs, proximity devices, and optical instruments. For product movement, transfer, and placement, palletizers rely on highly accurate pneumatic, electro-pneumatic, and electro-hydraulic motors, actuators, and drives.

Palletizer in plant.

Because of their high cycle life, smooth movement, precise control, and maintenance free operation, Kinetrol vane actuators have been very successfully used by palletizer OEMs. The actuator provides 90 degree and 180 degree rotation on the vacuum gripper head and pivot arms. During normal operation the Kinetrol actuators can see upwards of 20,000 cycle per day.

For more information on applying Kinetrol vane actuators to your packaging systems, contact:

Kinetrol USA
1085 Ohio Drive
Plano, Texas 75093
www.kinetrolusa.com
(972) 447-9443 phone
(972) 447-9720 fax

Superpulsator Vent Valve Operation Demands Performance

Kinetrol on Superpulsator Vent Valve

Water treatment involves multiple physical, chemical and biological processes that transform raw water into drinking water. Clarification, which includes the removal of excessive color or turbidity of raw water to produces clear uncolored water, is one of these processes. Clarification typically includes coagulation, flocculation and settling.

A Superpulsator unit is a simple type of clarification system utilizing an upward flow tank and inclined plate settling.  It operates by varying the level of the flocculation tank through the use of a vacuum pump and vent valve. The pump creates a vacuum in the tank causing the water level to rise. A vent valve then opens to atmosphere causing the water level to fall. The valve is then closed, and the process repeats itself continuously. The actuated vent valve is controlled by a timer set to pre-defined vacuum and vent cycles.

A Kinetrol USA Distributor was called in to assist in a water treatment plant’s upgrade to superpulsators. After reviewing the application, the Distributor specified 4" plug valves actuated with Kinetrol vane actuators and Kinetrol ULS limit switches. The plant’s original system was using double acting, air cylinder operated valves. These had to be replaced because they wouldn't be able to withstand the superpulsator's constant vacuum and venting cycling. The more robust Kinetrol actuator, capable of very high cycle rates, was clearly the best choice.

After installation and startup, and several years in operation, the Kinetrol actuators are performing flawlessly and are providing maintenance-free operation.

20" High Performance Butterfly Valve Closed in Under 1/2 Second!

Fast closing Kinetrol actuator

This video demonstrates how quickly a large butterfly valve can be closed with a Kinetrol vane actuator spring return unit. In this case, it's a 20" stainless steel high performance butterfly valve (HPBV) being tested in the shop.

You'll note the valve takes about 11 seconds to open, but only 0.4 seconds to close, using the Kinetrol spring return unit.

Quick closing valves are used in emergency situations to stop the flow of fluids that may contribute to uncontrolled combustion, cause backstream contamination, or allow spillage of hazardous materials.

1/4 Turn Electrohydraulic Valve Actuators

A hydraulic gear pump immersed in its own reservoir delivers pressurized oil to the vane-type 90° actuator via the control box, which contains non-return valves and solenoid valves to direct the flow into the actuator; with cam operated limit switches to control travel and (optionally) signal position to the user. The unpressurized side of the actuator is connected to the reservoir, so there is no net transfer of oil from reservoir to actuator. The pump and its motor run entirely on precision ball bearings, so that the friction and motor size can be minimized and life maximized; the efficiency resulting from this reduces the heating effect and allows 100% rating. A pressure release valve is built into the pump so that if the actuator load becomes jammed the torque is limited and dangerous over pressures or motor stalls are avoided.

Fail-safe spring return action uses a reliable low-stress-range sealed clock-type spring unit mounted coaxially with the actuator, together with a fail-open solenoid valve, to ensure reliable positioning when power is not supplied to the unit. A high flow external dump valve can be fitted to allow very rapid spring-driven action.

Double-acting models are supplied with solenoids arranged to give position locking when power is disconnected. An optional manual by- pass valve is available to allow manual override movement of a double acting when power is disconnected.

The interface between pump/reservoir unit and the control box allows mounting of the pump in different orientations at 90° to each other, so that the motor can be kept above the reservoir whether the actuator output axis is horizontal or vertical. External electrical connections are all made via a single accessible connector block in the control box, with the simplest possible switching needed to drive the unit. Two conduit entries are available, to allow easy separate connection of power and signal lines (if used). All internal wiring is connected via a central connector and fuse board, and the actuator is protected from supply surges by a metal oxide varistor suppressor.

For more information contact:

Kinetrol USA
www.kinetrolusa.com
972-447-9443