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Latest News from Cowan Dynamics

Why Use a Valve Actuator Limit Switch?

Why use a valve actuator limit switch? Valve automation is not simply the selection of the actuator. Control components are a big part of the complete actuation assembly.  When looking into the components that a valve automation system must have, we normally see solenoid valves which are used to control the pressurized fluid into the actuator. In addition, we also see what we often call position limit switches.  A valve actuator limit switch is a device that is designed to provide a remote signal to the control station, also known as PLC or DCS, regarding the valve position, often open or closed.  They can also be set to provide different position indications depending on the application. The switch will provide a signal on the position once the valve reaches it, therefore there will be...

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Knife Gate Valve Actuator

Knife gate valves are linear valves in which the closing membrane is a gate that is sharpened to better cut through the process media (such as slurry). The gate is connected to a stem and travels inside the valve body in which scrappers are often included to clean the gate as it moves from open to closed. They can be manual or automated, with metal or resilient seats, bi-directional, and come in wafer, lug and flange connections. Knife gate valves are very versatile and can be used in both isolation and control applications.  However, to provide good control characteristics the valve trims must be custom-made. Conventional resilient and metal seated knife gate valves are designed primarily for fluid isolation as they have poor control characteristics. Their ‘blade-like’ gate design makes...

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Butterfly Valve Actuator

Butterfly valves are rotary or 90-degree valves where the closing membrane is a disc that is connected to the stem perpendicularly either symmetrically or asymmetrically. They can be manual or automated, with metal or resilient seats, bi-directional, and come in wafer, lug, and flanged connections. Butterfly valves are very versatile and can be used in both isolation and control applications. However, their control capabilities are limited. Conventional resilient seated butterfly valves are designed primarily for fluid isolation as they have poor control characteristics. The seat is an elastic single piece that holds in place the valve body. This design can have its integrity compromised if the valve is kept partially open. For this reason, butterfly valves that are designed for control...

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What is a Valve Signature & How It Effects Actuator Sizing

A valve is a pressure vessel with internal moving parts; and when they move, they encounter resistance from other parts and from the flow. The recording of the pressures and forces associated with overcoming these resistances can be referred to as “valve signature”.  For actuator sizing, it is critical to obtain accurate valve thrust/torque data. This is especially true for spring-return actuators as conservative or exaggerated valve thrust/torque data can lead to extremely oversized and expensive actuators. The thrust or torque required to move the valve, in either direction, will vary throughout its stroke. In industry, the following  terms are used to describe the various data points required for actuator sizing: (fig.1 - see table for details) The thrust or torque...

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What is a Scotch Yoke valve actuator ?

Scotch yoke valve actuators are 90˚ driving mechanisms that can be powered by compressed air or hydraulic oil from an external source. Why consider a Scotch yoke valve actuator? Deciding which actuator is best for a certain application depends on several factors like environment, required accuracy, and close/open speed. When choosing between a 90˚ actuator such as a Rack & Pinion or Scotch Yoke, the main difference between these actuators are the torques they can generate. The following table shows the difference between the two main types of 90˚ actuators: How do they work? A scotch yoke actuator typically consists of a crank and piston system in a hollow cylinder. Pressure is applied to a side of the piston inside the cylinder. As a result, force is generated which...

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Valve Actuators

Valves are used to control the flow of fluids in process control applications by opening, closing, or partially obstructing the fluid flow and controlling the line pressure. Depending on the flow requirements of the process system, some method of changing the positions of valves is needed. Some valves are operated with hand wheels or levers. Other valves must be open, closed, or throttled frequently. Manually positioning valves in these types of situations is not practical and instead of using hand wheels or levers to control actuation, automated valve solutions such as valve actuators are used to position the valves. What is a valve actuator? A valve actuator is defined as a mechanical device that moves or controls a device such as a control valve. Actuators reduce the need for...

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How Pneumatic Actuators Work

What powers them? Pneumatic Actuators are powered by compressed gas from an external source, most commonly dry clean air. Usually, a single air compressor can drive several pneumatic actuators at the same time which gives them an advantage over other types of actuators especially if the system has a large number of valves. For example, in an electrical valve actuator a source of power (motor) has to be installed on each valve.   Why consider a pneumatic actuator? Deciding which actuator is the best for a certain application depends on several factors like environment, required accuracy and closure/open speed. However the main difference between actuators is the thrust or torque they can produce. Here are general applications for the main types of actuators:   Hydraulic...

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Types of Valves

What are valves? Valves are equipment that are designed to control fluids, they can open, close, regulate, or isolate. They can be as small as fractions of an inch and as large as 360 inches. They can be as simple as the copper valve found in a hardware store and as complex as custom-made valves in exotic alloys for nuclear reactors. Valves are one of the oldest products known to man, they are found in many of our everyday activities such as turning on the water in the sink.  Main parts of a valve Each type of valve has its own design features which govern its main parts, however there are 4 main components that every valve regardless of its type. These parts are the stem, the closing membrane, the body, and the seat. The stem: Part that transfer the energy from the operator to the valve...

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Gate Valve Actuator

What is a gate valve? Gate valves are linear valves where the closing membrane is a wedged disc or gate which moves perpendicular to the flow, allowing more flow as it moves away from the seat. These valves usually have metal seats and are bi-directional, the gate is wedged into the seat for which reason they are thrust seated valves. Gate valves are designed to be used as isolation or on/off valves therefore, are usually in a fully open or fully closed position. Normally in industry, they are flanged but also are offered in other connections such as threaded or welded. Gate Valve Applications They are often found at the end of pipelines where they serve as a final barrier against leaks before connecting into other pipelines or tanks, also very commonly used as isolation valves to do...

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Ball Valve Actuator

What is a ball valve? Ball valves are rotary or quarter-turn valves. Their closing membrane is a bored pivoting ball that is supported on one or both top and bottom ends. When the valve is open, the bore in the ball is aligned with the flow of the pipeline, allowing the substance to pass through. When closed (by turning the stem 90 degrees), the bore becomes perpendicular to the flow and stops it. These ball valves can have resilient or metal seats, are usually bi-directional and come in different connection configurations. The most common ball valve configuration being flanged and threaded.   Ball Valve Design Conventional ball valves are designed primarily for fluid isolation as they have poor control characteristics. The seat and body of a ball valve can be easily eroded if the valve...

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What are electrohydraulic actuators?

Electro-hydraulic actuators are devices that operate a valve through pressurized hydraulic fluid, however, their main source of energy is solely electrical. The electrical power supplied is used to energise a motor that runs a hydraulic pump which then supplies the pressurized fluid to operate a hydraulic actuator which controls the valve. The complete system is self-contained, eliminating the need for a separate hydraulic power unit, simplifying system construction and improving safety and reliability. A self-contained electrohydraulic actuator can be used with linear or rotary valves, the need for its use will depend on the requirements of the application. These devices are ideal for operating valves that need large torques or thrusts, or where fail-safe systems or high operating...

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Electrohydraulic Actuator vs. Electric Actuator

Due to their design, electric actuators have limitations in terms of output torques, duty cycle, failure modes, speeds, and vibration resistance.   In severe applications where valves with high torque or thrust must be operated quickly, such as emergency shutdown valves (ESDV), electric actuators have limitations because they can only store a certain amount of energy to operate the valve in the event of a power failure, which eliminates them as options in many emergency shutdown valve applications. In the same way, because they are operated directly by an electric motor, they present limitations in the operating speed; on one hand, the demand increases significantly as the speed increases and on the other hand, their operating speeds are constant since they depend on the RPMs of the...

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Efficient flotation Cell Level Control – AT Actuators for Dart Valves

Flotation cells are mechanical equipment that bring the ore in contact with air, water, and chemical agents. Their main function is to separate the previously conditioned slurry into a concentrate and tailings. The level of these cells is controlled by dart valves, which in turn are operated by actuators. The calculation of the level control valve (Dart) in flotation cells requires high consideration as the goal is accurate flow control to maximize slurry retention time and minimize downtime, therefore a reliable and accurate control valve actuator is essential. Traditionally dart valves use mechanical connections to feed position feedback to positioners that are then used to operate the actuators. The mechanical connections or arms, because they are exposed, are easily jammed, loosened,...

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Water hammer and its effects on valves operation

As we know, most liquids are considered non-compressible which means that no matter how much pressure is applied to them we can not modify their volume, they are not elastic. This characteristic is very useful in power transmission systems such as hydraulic pistons, however, can lead to catastrophic accidents in piping systems. The phenomenon of water hammer is based on this principle, when a volume of a fluid moves through a pipe carries inertia due to its weight, if we close a valve quickly, we are suddenly stopping the movement of this volume, which creates an abrupt increase of pressure, this energy has no way to dissipate or be absorbed due to the non-elasticity property of the fluid, so a wave is created that travels through the pipe until it finds a way to dissipate the energy....

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Electo-hydraulic Actuator VS Hydraulic Actuator

When comparing electro-hydraulic actuators vs hydraulic actuators, the electro-hydraulic actuator is self contained. Bulky and complex piping systems are not needed. The electro-hydraulic actuator control valve provides flexibility to easily control the opening and closing time of the valve. With standard hydraulic actuators cost of installation can be significantly higher due to the hydraulic piping infrastructure required. Whereas an electro-hydraulic actuator is self-contained and can be easily installed within hours. In addition, electro-hydraulics offer a wealth of real-time data to analyze valve/actuator performance over time. When comparing different valve actuators it is best to talk to one of our expert valve actuator sales professionals to help determine the ideal solution for...

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What is an Electro-Hydraulic Actuator

An electro-hydraulic actuator is an actuator that operates a valve via pressured hydraulic fluid however, its main source of energy is solely electric power. ​ The supplied electric power is used to energize a motor that runs a hydraulic pump which then supplies the pressurized fluid to operate a hydraulic actuator for the control valve. ​ The complete system is self-contained which eliminates the need for separated hydraulic power unit, simplifying the system construction and improving safety and reliability.  A self-contained electro-hydraulic actuator can be used with linear and rotary valves. It has been used with butterfly-valves and gate valves for various industrial applications.

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Press Release: C-PAC Module Pneumatic Manifold & Online Store

September 25, 2020   Cowan Dynamics is pleased to announce advancements to their “C-PAC Module” Pneumatic Manifold and the launch of the C-PAC store. The C-PAC (Cowan’s Pneumatic Actuator Control) is an out-of-the-box solution and can save up to 90% in assembly time and easily automate valve actuators without using cumbersome and costly piping to connect various automation components.   The C-PAC Pneumatic Manifold has the following capabilities for linear & 1/4 actuators:  speed control  safety pressure relief  fail-safe capabilities   Reliability & Safety  Valve actuator technicians and Valve Automation Centers have commented on the reliability and performance of the C-PAC Pneumatic Manifold. Its preassembled manifold configuration eliminates potential leak points and...

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Press Release: Expanded E2H Series | Electro-hydraulic Linear Valve Actuator

Montreal, Quebec  July 24, 2020  Cowan Dynamics is pleased to announce the release of their newly expanded E2H Series, Electro-Hydraulic Linear Valve Actuator. The electro-hydraulic actuator combines the best of both worlds of electric actuators and hydraulic actuators for control valve automation.   The E2H linear electo-hydraulic valve actuator replaces the need for separate, bulky hydraulic systems and complex hydraulic piping. In addition, the E2H can replace MOV (electric actuators) where 100% Duty Cycle, High Speed, and fail-safe requirements are of primary importance.   The updated brochure provides engineers with:  Details on How to Configure Multiple E2H Actuators  Mounting Flange Specifications & Dimensions  Bore Size / Motor / Thrust / Speed Specifications  Easy How...

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Pneumatic Manifold for Easy Valve Automation

Up to now when you needed a pneumatic control circuit for a double acting cylinder, you ended up with a very cumbersome and costly hardware assembly to setup control valve fail modes. The time and cost required to lay out and bend the various pipes, install fittings, control valves, and filter regulator components can run into the hundreds of dollars for the valve automation center or technician. Now you have an alternative. Cowan Dynamics offers the C-PAC module which is pneumatic manifold saving up to 90% in assembly time. The C-PAC is a one single pop-in unit that can be installed in a couple of minutes on any pneumatic cylinder. The shorter path flows resulted from using a pneumatic manifold for control valve automation reduces pressure drops and improves the overall system energy...

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Featured Valve Automation Actuators

A Series Feature

Designed and engineered for severe-service applications, the A Series bore sizes range from 4” to a whopping 42” diameter. We also offer a wide range of automation options.

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AS Series Feature

Next-generation “compact” model provides a shorter and lighter canister for installations where space is a premium.

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ML Series Feature

Our ML Series Double-Acting Hydraulic Valve Actuators are designed to suit a wide range of applications; from commodity to severe-service extremes.

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