Maximizing Efficiency in Oil and Gas with Direct Gas-Powered Scotch Yoke Actuators

Direct gas-powered scotch yoke actuators are critical in automating industrial valves, particularly in environments where high-pressure natural gas or other high-pressure fluids are readily available. These actuators convert the energy from high-pressure gas into mechanical motion, enabling the precise operation of large valves, including ball, plug, and butterfly valves. Their robust design and reliability make them essential in high-stakes applications such as gas transmission and petrochemical processing.

The operation of a direct gas-powered scotch yoke actuator hinges on the scotch yoke mechanism, a well-regarded design for its ability to generate high torque in a compact form. When high-pressure gas enters the actuator's cylinder, it exerts force on a piston. This piston is connected to a sliding yoke attached to a crank arm. As the piston moves under the force of the gas, the yoke slides, causing the crank arm to rotate. This rotational motion is then transferred to the valve stem, causing the valve to open or close depending on the direction of the rotation.

One of the defining characteristics of the scotch yoke mechanism is its ability to produce a high torque output at the beginning and end of the valve stroke. This feature is particularly advantageous in valve automation because it matches the torque profile required by many valves, which often need higher torque to unseat from a closed position and achieve the final seal during closure. In many heavy-duty applications, the scotch yoke actuator's ability to deliver peak torque at these critical moments makes it more efficient and effective than other actuator designs, such as the rack and pinion mechanism.

Direct gas-powered scotch yoke actuators are favored in remote or hazardous locations where electricity is unreliable or unsafe. In natural gas pipelines, for instance, the actuator can utilize the gas being transported through the pipeline as its power source, eliminating the need for an external power supply and reducing the complexity of the installation. This capability not only enhances the reliability of the system but also lowers operational costs.

In the oil and gas industry, direct gas-powered scotch yoke actuators are essential for ensuring safe and reliable valve automation across various operations. They play a critical role in controlling the flow of hydrocarbons within refineries, gas processing plants, and other key facilities where precision and safety are of the utmost importance. Thanks to their high torque output and robust design, these actuators are particularly well-suited for managing the large, high-pressure valves commonly encountered in such environments.

Scotch yoke actuators' ability to convert high-pressure gas into powerful rotational force makes them indispensable in oil and gas settings that demand reliability and efficiency. Their simple yet effective mechanism perfectly aligns with the industry's need for consistent performance in operating large industrial valves. From upstream applications like wellhead control to downstream processes such as refining and distribution, these actuators ensure the safe and efficient management of critical flow processes, contributing to the overall safety and productivity of oil and gas operations.

Mead O'Brien
https://meadobrien.com
(800) 874-9655

Gas Powered Actuators for the Oil and Gas Industry

The gas-powered scotch yoke actuator is a mechanical device designed to convert linear motion into rotary motion, primarily used for valve actuation in the oil and gas industry and other industrial applications requiring precision control of fluid flow. This actuator is particularly advantageous for heavy-duty and high-torque applications, offering reliable and efficient operation with minimal maintenance. Here's a detailed overview of how it operates and its primary application:

Operation:

1. Gas supply: The gas-powered scotch yoke actuator uses pressurized gas as the driving force, which, depending on the specific application and site requirements, the gas source is a natural gas pipeline, an onsite compressor, or bottled gas.
2. Pneumatic cylinder: The gas enters the pneumatic cylinder, which is the core component of the actuator. The cylinder contains a piston that moves linearly when pressurized gas is applied.
3. Scotch yoke mechanism: The linear motion of the piston is converted into rotary motion using the scotch yoke mechanism. The scotch yoke consists of a yoke (a slotted, U-shaped component) attached to the piston rod and a pin mounted on the rotating output shaft. The yoke slides along the pin as the piston moves linearly, causing the output shaft to rotate.
4. Output shaft: The output shaft's rotation is transferred to the valve stem, causing the valve to open or close, depending on the direction of the rotation. The shaft is connected to the valve using a coupling, which ensures proper alignment and torque transmission.
5. Spring return mechanism: Some gas-powered scotch yoke actuators have a spring return mechanism, which enables the valve to return to a predetermined fail-safe position in the event of a loss of gas supply or system failure.

Primary application: The primary application of the gas-powered Scotch yoke actuator is in the oil and gas industry, where it controls various types of valves, such as ball valves, butterfly valves, and plug valves. These valves are essential for regulating the flow of oil, gas, or other fluids in pipelines, processing plants, and other facilities.

The actuator's high torque capabilities make it suitable for heavy-duty applications, such as large-diameter or high-pressure valves. Additionally, the gas-powered design offers several advantages over electric or hydraulic actuators, including lower operating costs, reduced environmental impact, and compatibility with remote or hazardous locations where electricity or hydraulic power may not be readily available.

Limitorque has established a dominant position in the gas-powered scotch yoke actuator market, owing to its reputation for delivering high-quality, reliable, and efficient products. Their actuators are known for their durability and low maintenance requirements, making them a preferred choice for heavy-duty applications in the oil and gas industry. The company's commitment to continuous innovation and its extensive experience in the field has allowed them to develop customized solutions to address the unique challenges faced by its customers. Furthermore, Limitorque's strong global presence and extensive support network ensure they provide exceptional after-sales service, reinforcing their position as a trusted leader in the market.

Mead O'Brien

https://meadobrien.com

(800) 892-2769

Industrial Actuators, Valves, and Positioners

Valves regulate fluid flow to provide accurate control and safety in any given process system, and methods of adjusting valve position are always required.

Commonly, valves are operated with handwheels or levers, although some must be regularly opened, closed, or throttled. In certain conditions, it is not always practical to position valves manually; hence actuators are employed instead of hand wheels or levers. 

An actuator is a mechanism that moves or regulates a device, such as a valve. Actuators decrease the requirement for people to operate each valve manually. Valves using actuators can remotely control valve position, particularly crucial in applications where valves open and close or modulate fast and precisely. 

Pneumatic, hydraulic, and electrical actuators are the three fundamental types. 

1. Pneumatic actuators employ air pressure to generate motion and are probably the most prevalent type of actuator utilized in process systems. 
2. Actuators powered by a pressurized fluid, such as hydraulic fluid, are called hydraulic actuators. Typically, hydraulic actuators of the same size produce more torque than pneumatic actuators. 
3. Electric actuators generate motion using electricity. Actuators usually belong to two broad categories: solenoid or motor-driven actuators. 

Actuators position valves in response to controller signals and can be positioned rapidly and precisely to accommodate frequent flow variations. The instrumentation systems that monitor and respond to fluctuations in plant processes include controllers. Controllers receive input from other instrumentation system components, compare that input to a setpoint, and provide a corrective signal to bring the process variable (such as temperature, pressure, level, or flow). 

You have a control valve when actuators pair with flow-limiting or flow-regulating valves. Generally speaking, control valves automatically restrict flow to provide accurate flow to a process to maintain product quality and safety. 

Control valves can be linear, where the stem moves the valve disk up and down like globe valves, or rotational. Rotary control valves include butterfly valves, which open or close with a 90-degree rotation. The pneumatic diaphragm and electric actuators are the most prevalent on linear and rotational control valves.

Some valves require long stem travel or substantial force to change position. A piston actuator's higher torque is preferable to diaphragm actuators in these situations. Examples of piston actuators are rack and pinion and scotch-yoke designs. 

Single-acting piston actuators control the air pressure on one side of a piston, and with higher air pressure, the piston moves within the cylinder and turns the valve. The air on the opposite side of the piston exits the cylinder via an air vent. With decreased air pressure, the spring expands, causing the piston to move in the opposite direction. 

If air pressure falls below a predetermined threshold or is lost, the spring will push the piston to the desired position, referred to as the "fail" position (open or closed). 

A double-acting piston actuator lacks a spring and has air supply ports on both ends of the cylinder. Increasing air pressure to the supply port moves the valve in one direction. Higher pressure air entering from the opposite supply port pushes the valve in the opposite direction. Filling the cylinder with air and releasing air from the cylinder is regulated by a device known as a positioner. 

Typically, the control of pneumatic actuators occurs from air signals from a controller. Some actuators react directly from a controller, for instance, a pneumatic 3-15 PSI controller output. Sometimes, a controller signal alone cannot counteract a valve's friction or the process media's fluid pressure. This situation requires a separate, high pressure air supply and modulating it with a pneumatic or electro-pneumatic positioner. These devices regulate a high pressure air supply to ensure that an actuator has enough torque to position a valve accurately. The positioner responds to a change in the controller's air, voltage, or current signal and proportions the high pressure air to the actuator. Connecting the actuator stem to the positioner is a mechanical linkage. This mechanical connection is also known as a feedback connection. The link moves as the actuator stem moves up, down, or rotationally. The location of the connection informs the positioner when sufficient movement coincides with the controller's air signal. The controller's signal transmits to the positioner instead directly to the actuator, and the positioner regulates the air supply provided to the actuator.

Like other process components, actuators are prone to mechanical issues. Since actuator issues can negatively impact the operation of a process, it is essential to be able to recognize actuator issues when they occur. Frequently, an operator can notice an actuator fault by comparing the valve position indication to the position specified by the controller. For instance, if the position indicator shows the valve closed, but the flow indicator on the controller indicates that flow is still passing through the valve, the valve seat and disc are likely worn, enabling leakage through the valve.

Because there are so many different styles and designs of actuators, positioners, and valves and so many industrial applications, the combination possibility matrix is vast. You must discuss your application with a knowledgeable, experienced valve expert. The success of your project in terms of product quality, system cost, maintenance, and safety depends upon it.

Mead O'Brien
(800) 874-9655

White Paper :Ten Reasons to Consider Brushless DCV Motors in Electric Valve Actuators

This paper, courtesy of Flowserve Limitorque, aims to investigate the most recent advancements in these motors, consider alternatives, and discuss how to make an informed decision about when and where to use BLDC motor technologies.

Brushless DC motors are synchronous motors powered by a direct current source via an electric controller rather than the brush/commutator mechanism used in brushed DC motors. The electric controller, an integrated inverter/switching power supply, generates an alternating current signal that drives the rotor. Electronically commutated motors, ECMs, or EC motors are other names for them.

Brushless DC electric (BLDC) motors have been around for nearly 50 years, but their use for intelligent actuation is relatively new. Their adaptation is critical to the improvement of process control and plant safety systems.

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DOWNLOAD THE WHITE PAPER HERE

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How to Set the Position Limits on a Limitorque L120 Electric Actuator

The Flowserve Limitorque L120 electric actuator is designed for a wide range of environmental applications in power, oil & gas, and water industries.

The purpose of this instructional video to demonstrate the proper method of setting position limits on the Limitorque L120 electric actuator in a safe manner. Explore the video to learn correct equipment terminology, understand the wiring diagram with respect to the limit switch contact development and learn how to read the position of the limit switch.

Rugged, reliable and versatile, L120 actuators are proven performers in challenging applications. Thousands of L120 actuators are at work in some of the world’s most demanding conditions, where nothing less than day-after-day dependable operation is acceptable.

Petrochemical installations such as refineries, pipelines, terminals, tank farms, cokers and off-shore platforms rely on the L120’s safety, endurance and operational efficiencies. The L120 has network compatibility, explosion-proof certification, and resistance to lightning and EMI.

Power Generation plants value the L120’s availability, controls versatility and reliable performance. The L120’s rugged design and construction quality stands up to vibration, high-pressure steam and extreme temperatures.

Water and Waste Treatment Facilities benefit from the L120’s low-maintenance requirements and modulating control capabilities. L120 actuators meet AWWA standards and easily fit the industry trend toward modern controls networks. The wide range of options in the L120 Series allows specification needs to be met cost-effectively.

Mead O'Brien
https://meadobrien.com
(800) 892-2769

Leading Edge Electric Actuators - The Limitorque MXb

The Limitorque MXb electric actuator performs across a broad range of challenging applications where reliability is critical, including oil and gas; commercial power; chemical; fresh and wastewater; and general industries.

Improved reliability

The actuator's design isolates critical components, protecting them from electrical shock and interference, typical in extreme environments. High-quality materials extend actuator service life, operating ranges, and mean time between failure.

Enhanced user experience

An updated user interface coupled with a simplified, intuitive menu structure and larger, high-resolution LCD screen makes navigation easy and enables 50% faster commissioning, set-up, and operation. Users of any skill level can configure the actuator through various pre-configured or customization options for quick and error-free set-up and operation. A larger, higher-resolution LCD with a built-in ambient light sensor offers eight times the previous display's resolution to extend viewing distances up to 30 feet. Real-time torque graphs, alarm and event logs, and other data are accessible in higher-quality resolution.

Advanced diagnostics and analytics

The MXb electric actuator's next-generation diagnostics and analytics capabilities help operators monitor and track its performance and quickly respond to upset conditions. The MXb actuator has 500 times the previous MX model's memory capacity, allowing increased data capture and storage for higher degrees of process monitoring, data logging, and information feedback. Additionally, a real-time clock enables data log time stamping to support asset management functions and lifecycle analysis.

Simplified maintenance

A new electric connector design removes the need for brackets and hold-downs, making maintenance more straightforward and faster. And the enhanced connector design ensures robust connectivity throughout the rated seismic and vibration envelope.

For more information about the Limitorque MXb contact Mead O'Brien by calling (800) 892-2769 or visiting their website at https://meadobrien.com. 

What is a Ball Valve?

Cutaway of specialized ball valve with characterized
ball for control valve applications. (Neles)

A ball valve is a 90 degree rotational motion valve that uses a metal or ceramic ball with a hole through its center to stop or start fluid flow. The ball, shown below in Figure 1, opens and closes to allow fluid flow through the ball valve. When the valve handle or stem is turned to open the valve, the ball rotates to a point where the hole in the ball is parallel with the valve body inlet and outlet. When the valve is shut, the ball is rotated so that the ball's hole is perpendicular to the inlet and outlet of the valve body and the flow is stopped.

Most ball valve actuators are of the quick-acting type, which require a 90° turn of the valve handle or stem to operate the valve. Other ball valve actuators are planetary gear-operated manual,  electrically operated motors, or pneumatic piston type. All actuators provide the necessary operating force to open and close valves.

Figure 1 

Ball Valve Advantages

A ball valve is often the least expensive of any industrial valve configuration and has low maintenance costs. In addition to quick, quarter turn on-off operation, ball valves are compact, require no lubrication, and give tight sealing with low torque.

Ball Valve  Disadvantages

Conventional industrial ball valves have relatively poor throttling characteristics (except when using a characterized ball, as shown above). A standard ball valve when in throttling position will fail because of because of the impingement of high velocity flow and the erosive effect on the partially exposed seat.

Ball Valve Port Patterns

Ball valves are available in the venturi, reduced, and full port pattern. The full port pattern has a ball with a bore equal to the inside diameter of the pipe.

Ball Valve Materials

Balls are usually metallic in metallic bodies with trim (seats) produced from "soft" seats referring to the elastomeric materials used such as PTFE (100% Virgin Polytetrafluoroethylene), RTFE (Reinforced Teflon®), TFM, CTFE, Polychlorotrifluoroethene, Polyether Ether Ketone, and UHMWPE. Care must be used in the selection of the seat material to ensure that it is compatible with the materials being handled by the valve.Ball valve bodies may also be made of various plastic materials for corrosive applications.

Ball Valve Stem Design

The stem in a ball valve is not fastened to the ball. It normally has a rectangular portion at the ball end which fits into a slot cut into the ball. The enlargement permits rotation of the ball as the stem is turned.

Ball Valve Bonnet Design

A bonnet cap fastens to the body, which holds the stem assembly and ball in place. Adjustment of the bonnet cap permits compression of the packing, which supplies the stem seal. Packing for ball valve stems is usually in the configuration of die-formed packing rings normally of TFE, TFE-filled, or TFE-impregnated material. Some ball valve stems are sealed by means of O-rings rather than packing.

Ball Valve Position

Some ball valves are equipped with stops that permit only 90° rotation. Others do not have stops and may be rotated 360°. With or without stops, a 90° rotation is all that is required for closing or opening a ball valve.

The handle indicates valve ball position. When the handle lies along the axis of the valve, the valve is open. When the handle lies 90° across the axis of the valve, the valve is closed. Some ball valve stems have a groove cut in the top face of the stem that shows the flowpath through the ball. Observation of the groove position indicates the position of the port through the ball. This feature is particularly advantageous on multiport ball valves.

For more infomration about industrial ball valves, contact Mead O'Brien by calling (800) 892-2769 or visit their website at https://meadobrien.com.

White Paper: Intrusive vs. Non-Intrusive Electric Actuators: Which option is right for your installation?

Modern electric actuators offer a wide range of technologies and features, from basic motor controls to sophisticated electronic controls. Many choices are available, since no single design or feature set meets the needs of every application.

Actuators are motorized gear drives that control the operation of multi-turn valves, slide gates and dampers; or quarter-turn valves and dampers. Some actuators, including those compared in this paper, use electricity as a power source. Other types of actuators, such as those powered by hydraulic fluid or pneumatic pressure, are not addressed in this paper. Applications vary, requiring the user to select some form of actuator control system. Typical control systems range from simple electro-mechanical controls found in intrusive actuator designs, to solid-state electronic controls found in non-intrusive designs.

DOWNLOAD THE FULL WHITE PAPER HERE

Mead O'Brien
https://meadobrien.com
(800) 892-2769

Intrusive vs. Non-Intrusive Electric Actuators: Which option is right for your installation? from Mead O'Brien, Inc.

Limitorque Fluid Power Systems (LFPS)

Limitorque Fluid Power Systems is a group of modular scotch yoke fluid power actuators designed to deliver maximum torque with the lowest possible displacement and overall size. These heavy-duty, fluid-powered valve actuators and control systems are design primarily for the oil and gas industry. The group is categorized into three major sub-groups:

• Gas Powered Actuators - The Limitorque LDG direct gas actuator is designed to operate on high pressure pneumatic supply, including pipeline gases, nitrogen and any other equivalent high pressure source.
• Hydraulic Actuators - LHS and LHH are Limitorque’s range of hydraulic, quarter-turn, scotch yoke actuators. Designed to meet or exceed the most current and stringent safety and reliability standards for application in the oil and gas industry LHS and LHH are suitable for on/off and modulating control of all quarter-turn valves. 
• Pneumatic Actuators - Limitorque’s LPS and LPC are pneumatic quarter turn scotch yoke actuators, featuring a robust design suitable for heavy duty services, and among the longest design lifespans and maintenance intervals in the industry.

Download the Limitorque Fluid Power Systems PDF here.

Mead O'Brien
www.meadobrien.com
(800) 892-2769

Electric Valve Actuation

Limitorque Electric Valve Actuator

Electric actuators use electrical power to actuate a valve. While most of the basic technology used in electric actuators has been around since the 1930s, decades of incremental improvement have significantly increased their functionality while dramatically reducing their cost. In recent years, these advances have reached a tipping point that makes electric actuators the first choice for a wide variety of applications.

Pros

• Electric power is relatively inexpensive, easy to manage, and normally available to most industrial sites. The capital cost of electric actuators is typically cheaper per equivalent unit of torque/thrust output. They’re also cleaner and safer to operate. 
• Electric actuators can provide superior positioning accuracy for control or modulating valve functions, which can include provisions for a high degree of process monitoring, data logging and information feedback. 
• All necessary control functions are integral to electric actuators, reducing capital costs. 
• Electric actuators significantly reduce control wiring costs by enabling distributed control. They simplify control logic by integrating control commands and feedback into customer SCADA or DCS systems. (Traditional electromechanical control systems require a dedicated wire for each command and feedback signal, leading to cable bundles with seven or more cores as minimum for each actuator. By contrast, a typical bus system can use one twisted pair wire in a daisy chain configuration to carry all required input and output signals.) 
• As torque and thrust requirements increase, electric actuators weigh less and have smaller footprints compared to pneumatic actuators. 
• Electric actuators may be combined with external gearboxes to produce extremely high output thrust and torque values.

Cons

• With the exception of a few specific configurations, electric actuators can’t guarantee a fail-safe stroke but will “fail in the last position.” (Fail-safe stroke refers to an actuator’s ability to move a valve to a predefined safe position when power fails).
• Electric actuators have more complex and sensitive components than the mechanical parts used in other types of actuators. Electronic technology also requires periodic refreshing to keep pace with component changes and improvements.
• Beyond a certain size/torque range, electric actuators are less cost-effective and generally have limitations in operating speed when compared to pneumatic and hydraulic actuators.
• In hazardous areas with potential exposure to explosive process media, electric actuators require more specific certifications and construction features to be considered safe for use.

Recommended applications

Electric actuation is the first choice for most oil and gas applications. They’re ideal for general process valve automation, non-critical applications, and light-duty modulating applications (generally up to 1200 starts per hour), although some can modulate continuously up to 3600 starts per hour.

Reprinted with permission from the Flowserve Limitorque white paper titled "Valve Actuation: The When, How and Why of Actuator Selection" which can be downloaded here.

Expert Valve Automation and Valve Communications Services

With expertise in pneumatic rack and pinion and scotch-yoke, as well as electric quarter-turn and linear, Mead O'Brien has the experience and facilities to deliver a well engineered automated valve package.

Call (800) 892-2769 or visit https://meadobrien.com for more information on any valve automation requirement.

Industrial Valve Actuators

Valve actuators are selected based upon a number of factors including torque necessary to operate the valve and the need for automatic actuation. Types of actuators include manual handwheel, manual lever, electrical motor, pneumatic, and solenoid. All actuators except manual handwheel and lever are adaptable to automatic actuation.

Handwheel (Metso)

Manual Actuators

Manual actuators are capable of placing the valve in any position but do not permit automatic operation. The most common type mechanical actuator is the handwheel. This type includes handwheels fixed to the stem and handwheels connected to the stem through gears.

Electric Motor Actuators

Electric Actuator (Limitorque)

Electric motors permit manual, semi-automatic, and automatic operation of the valve. Motors are used mostly for open-close functions, although they are adaptable to positioning the valve to any point opening. The motor is usually a, reversible, high speed type connected through a gear train to reduce the motor speed and thereby increase the torque at the stem. Direction of motor rotation determines direction of disk motion. The electrical actuation can be semi-automatic, as when the motor is started by a control system. A handwheel, which can be engaged to the gear train, provides for manual operating of the valve. Limit switches are normally provided to stop the motor automatically at full open and full closed valve positions. Limit switches are operated either physically by position of the valve or torsionally by torque of the motor.

Pneumatic Actuators

Pneumatic Actuator
(Metso Neles)

Pneumatic actuators provide for automatic or semi-automatic valve operation. These actuators translate an air signal into valve stem motion by air pressure acting on a vane, diaphragm, or piston connected to the stem. Pneumatic actuators are used in throttle valves for open-close positioning where fast action is required. When air pressure closes the valve and spring action opens the valve, the actuator is termed direct-acting. When air pressure opens the valve and spring action closes the valve, the actuator is termed reverse-acting. Double acting actuators have air supplied to both sides of the vane, diaphragm, or piston. The differential pressure across the diaphragm positions the valve stem. Automatic operation is provided when the air signals are automatically  controlled by circuitry. Semi-automatic operation is provided by manual switches in the circuitry to the air control valves.


Hydraulic Actuators

Hydraulic actuators provide for semi-automatic or automatic positioning of the valve, similar to the pneumatic actuators. These actuators use a piston to convert a signal pressure into valve stem motion. Hydraulic fluid is fed to either side of the piston while the other side is drained or bled. Water or oil is used as the hydraulic fluid. Solenoid valves are typically used for automatic control of the hydraulic fluid to direct either opening or closing of the valve. Manual valves can also be used for controlling the hydraulic fluid; thus providing semi-automatic operation.

Solenoid Actuated Valves

Solenoid Valve (ASCO)

Solenoid actuated valves provide for automatic open-close valve positioning. Most solenoid actuated valves also have a manual override that permits manual positioning of the valve for as long as the override is manually positioned. Solenoids position the valve by attracting a magnetic slug attached to the valve stem. In single solenoid valves, spring pressure acts against the motion of the slug when power is applied to the solenoid. These valves can be arranged such that power to the solenoid either opens or closes the valve. When power to the solenoid is removed, the spring returns the valve to the opposite position. Two solenoids can be used to provide for both opening and closing by applying power to the appropriate solenoid.

Single solenoid valves are termed fail open or fail closed depending on the position of the valve with the solenoid de-energized. Fail open solenoid valves are opened by spring pressure and closed by energizing the solenoid. Fail closed solenoid valves are closed by spring pressure and opened by energizing the solenoid. Double solenoid valves typically fail "as is." That is, the valve position does not change when both solenoids are de-energized.

One application of solenoid valves is in air systems such as those used to supply air to pneumatic valve actuators. The solenoid valves are used to control the air supply to the pneumatic actuator and thus the position of the pneumatic actuated valve.

Mead O'Brien can handle any valve actuation requirement you have. Contact them by calling (800) 892-2769 or by visiting https://meadobrien.com.

Flowserve Limitorque WG Series Gear Operator Installation, Maintenance, and Operation Guide

WG Series Gear Operator (Limitorque)

The most basic function of a valve is to be opened and closed, allowing or preventing a process media to flow. Gearboxes, such as the WG series, provide the mechanical advantage to make hand operation possible for most valves.

The Flowserve Limitorque WG series of worm gearboxes is designed for quarter-turn butterfly, ball, and plug valve applications as well as quarter-turn and multi-turn dampers and offers unsurpassed quality and longevity in a wide variety of weatherproof, submersible and buried-service applications.

The following installation and maintenance manual (IOM) explains how to install and maintain the Flowserve Limitorque WG operator. Information on installation, disassembly, reassembly, lubrication and spare parts is provided in the embedded document below.

Alternatively, you can conveniently download the Limitorque WG Series Installation, Operation, and Maintenance in PDF here.

Limitorque WG Series Installation, Operation, and Maintenance from Mead O'Brien, Inc.

Industrial Valve Actuator Basics

Electric actuator (Limitorque)

Actuators are devices which supply the force and motion to open and close valves. They can be manually, pneumatically, hydraulically, or electrically operated. In common industrial usage, the term actuator generally refers to a device which employs a non-human power source and can respond to a controlling signal. Handles and wheels, technically manual actuators, are not usually referred to as actuators. They do not provide the automation component characteristic of powered units.

The primary function of a valve actuator is to set and hold the valve position in response to a process control signal. Actuator operation is related to the valve on which it is installed, not the process regulated by the valve. Thus a general purpose actuator may be used across a broad range of applications.

Pneumatic actuator (Metso Neles)

In a control loop, the controller has an input signal parameter, registered from the process, and compares it to a desired setpoint parameter. The controller adjusts its output to eliminate the difference between the process setpoint and process measured condition. The output signal then drives some control element, in this case the actuator, so that the error between setpoint and actual conditions is reduced. The output signal from the controller serves as the input signal to the actuator, resulting in a repositioning of the valve trim to increase or decrease the fluid flow through the valve.

An actuator must provide sufficient force to open and close its companion valve. The size or power of the actuator must match the operating and torque requirements of the companion valve. After an evaluation is done for the specific application, it may be found that other things must be accommodated by the actuator, such as dynamic fluid properties of the process or the seating and unseating properties of the valve. It is important that each specific application be evaluated to develop a carefully matched valve and actuator for the process.

Hydraulic and electric actuators are readily available in multi-turn and quarter-turn configurations. Pneumatic actuators are generally one of two types applied to quarter-turn valves: scotch-yoke and rack and pinion. A third type of pneumatic actuator, the vane actuator, is also available.

For converting input power into torque, electric actuators use motors and gear boxes while pneumatic actuators use air cylinders. Depending on torque and force required by the valve, the motor horsepower, gearing, and size of pneumatic cylinder may change.

Linear pneumatic actuator (Neles)

There are almost countless valve actuator variants available in the industrial marketplace. Many are tailored for very narrow application ranges, while others are more generally applied. Special designs can offer more complex operating characteristics. Ultimately, when applying actuators to any type of device, consultation with an application specialist is recommended to help establish and attain proper performance, safety and cost goals, as well as evaluation and matching of the proper actuator to the valve operation requirements. Share your fluid process control requirements with a specialist in valve automation, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Limitorque QX Electronic Actuator User Instructions

Limitorque QX

The Flowserve Limitorque QX quarter-turn smart electronic valve actuator continues the legacy of the industry’s state-of-the-art, non-intrusive, multi-turn MX actuator by including an absolute encoder for tracking position without the use of troublesome batteries. The QX design provides enhanced safety and reduced downtime through improved diagnostics, built-in self-test (BIST) features and LimiGard™ fault protection.

The QX design builds on more than 10 years of experience with proven Limitorque MX technology - the first generation double-sealed electronic valve actuator from Flowserve designed to provide control, ease of use and  accuracy. The QX includes all the user-preferred features of the MX in a quarter-turn smart actuator package. It is the only non-intrusive, double-sealed quarter-turn actuator to display the Limitorque brand.

For more information on any Limitorque actuator, visit Mead O'Brien at http://www.meadobrien.com or call (800) 892-2769.

Limitorque QX Electronic Actuator User Instructions from Mead O'Brien, Inc.

BIST (Built-in-Self-Test) Features for Electronic Valve Actuators

Electric actuator (Limittorque)

Abstract

The development and implementation of safety related devices in plant systems is crucial for dependable operation, not to mention peace of mind. Safety and safe operation were once only high priorities for installations that involve hazardous environments. Expensive certification testing was, and still is, paramount to meeting the hazards of such environments, but a new level of plant-wide integrity is emerging — that of Safety Integrity Level (SIL) and SIS. SIL is a safety rating that can be derived by analyzing a system to determine the risk of a failure occurring and the severity of its consequences. Safety Instrumented Systems (SIS) are systems containing instrumentation or controls installed for the purpose of preventing or mitigating a failure either by emergency shut down (ESD) or diverting the hazard. New or replacement equipment must have the ability to be introduced into plant systems without jeopardizing either the SIL of the operation or negatively impacting the SIS.

Read the entire white paper below.

For more information visit this link or contact:

Mead O'Brien
www.meadobrien.com

(800) 892-2769

BIST (Built-in-Self-Test) Features for Electronic Valve Actuators from Mead O'Brien, Inc.

Limitorque Blue Ribbon Service by Mead O'Brien

Limitorque factory trained technicians, support and parts.  It's only factory authorized when the work is done by a Blue Ribbon Repair Center.

Your Limitorque actuators were a major investment. Don't take chances with an unknown. Choose only a Flowserve Limitorque Blue Ribbon Distributor to assure you're getting factory authorized service. It's just not worth the risk.

Flowserve Limitorque Actuators: General Safety Precautions and Practices

Limitorque multi-turn actuator.

The following are general guidelines for safely operating Limitorque actuators. This post is intended to supplement Flowserve / Limitorque's ongoing efforts to provide information on the safe and proper use of electric valve actuators on industrial globe, gate, ball, butterfly and plug valves.  It is critically important to always refer to the installation & maintenance manual before applying, installing and servicing Limitorque actuators. If unsure about any of the recommended safety or installation procedures, contact a factory authorized technician before going any further.

More than 1 million Limitorque actuators have been installed around the world, and some have been in operation for more than 50 years. The ruggedness and reliability of Limitorque electric actuators are among the primary reasons that customers continue to select Limitorque products.

Actuators requiring 90° of rotation to operate are necessary for quarter-turn valves such as ball, butterfly, plug and dampers, and rotary control valves. These types of Limitorque electric actuators are available for operations such as open-close, modulating, network and rotary service.

Multi-turn actuators are required to operate various types of rising stem valves such as gate, slide-gates, globe, check and linear control valves. These types of Limitorque electric actuators are available for operations such as open-close, modulating, network and linear service.

General Safety Precautions

1. Warning: Read the Installation and Maintenance Manual carefully and completely before attempting to install, operate, or troubleshoot the Limitorque actuator.
2. Warning: Be aware of electrical hazards. Turn off incoming power before working on the actuator and before opening the switch compartment.
3. Warning: Potential HIGH PRESSURE vessel — be aware of high-pressure hazards associated with the attached valve or other actuated device when installing or performing maintenance on the actuator. Do not remove the actuator mounting bolts from the valve or actuated device unless the valve or device stem is secured or there is no pressure in the line.
4. Warning: For maintenance and/or disassembly of the actuator while installed on the valve, ensure that the actuator is not under thrust or torque load. If the valve must be left in service, the valve stem must be locked in such a way as to prevent any movement of the valve stem.
5. Warning: Do not attempt to remove the spring cartridge cap, housing cover, or stem nut locknut from the actuator while the valve or actuated device is under load.
6. Warning: Do not manually operate the actuator with devices other than the installed handwheel and declutch lever. Using force beyond the ratings of the actuator and/or using additive force devices such as cheater bars, wheel wrenches, pipe wrenches, or other devices on the actuator handwheel or declutch lever may cause serious personal injury and/or damage to the actuator and valve.
7. Warning: Do not exceed any design limitations or make modifications to this equipment without first consulting Limitorque.
8. Warning: Actuators equipped with electrical devices (motors, controls) requiring field wiring must be wired and checked for proper operation by a qualified tradesman.
9. Warning: Use of the product must be suspended any time it fails to operate properly.
10. Caution: Do not use oversized motor overload heaters. Instead, look for the cause of the overload.
11. Caution: Do not operate the valve under motor operation without first setting or checking the limit switch setting and motor direction.
12. Caution: Do not force the declutch lever into the motor operation position. The lever returns to this position automatically when the motor is energized.
13. Caution: Do not depress the declutch lever during motor operation to stop valve travel.
14. Caution: Do not use replacement parts that are not genuine Flowserve Limitorque parts, as serious personal injury and/or damage to the actuator and valve may result.
15. Caution: Do not lift actuator/gearbox or actuator/valve combinations with only the eye bolts in the SMB actuator. These eye bolts are designed for lifting the SMB actuator only.

General Safety Practices

The following check points should be performed to maintain safe operation of the actuator:

1. Eye bolts in SMB and SB actuators are designed for lifting only the actuator and not associated gearboxes or valves.
2. Mount the actuator with the motor in a horizontal plane, if possible.
3. Keep the switch compartment clean and dry.
4. Keep the valve stem clean and lubricated.
5. Set up a periodic operating schedule for infrequently used valves.
6. Verify all actuator wiring is in accordance with the applicable wiring diagram.
7. Carefully check for correct motor rotation direction. If the valve closes when open button is pushed, the motor leads may have to be reversed.
8. Verify the stem nut is secured tightly by the locknut and that the top thread of the locknut is crimped or staked in two places.
9. Use a protective stem cover. Check valve stem travel and clearance before mounting covers on rising stem valves.

Mead O'Brien Authorized
Blue Ribbon Limitorque Parts & Service

For more information, or if you need field support with any Limitorque actuator, parts, or service, contact one of the following Mead O'Brien offices: 

www.meadobrien.com

Mead O’Brien, Inc.
10800 Midwest Industrial Blvd
St. Louis, Missouri 63132
(314) 423-5161

Mead O’Brien, Inc.
1429 Atlantic
North Kansas City, MO 64116
(816) 471-3993

Mead O’Brien, Inc.
16 South Main Street
PO Box 1086
Calvert City, Kentucky 42029-1086
(270) 395-7330

Mead O’Brien, Inc.
824 West Elgin
Broken Arrow, Oklahoma 74012
(918) 251-1588