Cowan Connection

Latest News from Cowan Dynamics

Maximize flotation cell mineral recovery

In this article you'll learn to maximize mineral recovery in a flotation cell. Dart valves have traditionally been used as level control valves in flotation cells. The dart valve positioning in flotation cells requires high consideration as the goal is to maximize mineral recovery. For this reason a reliable and accurate control valve actuator is crucial. Pneumatic actuators vs electro-hydraulic actuators for dart valve control  Traditionally dart valves use pneumatic actuators to control the flotation cell level.  However, due to air compression or elasticity, this method of automation can cause problems in accurate and efficient level control. The thrust due to the pressures at the bottom of the cell acts...

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What are electro-hydraulic 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...

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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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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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