Posted by RWVC on | Comments Off on A Guide to Valve Actuators
At RED-WHITE VALVE CORP., we are a premier supplier of valves and related products for the plumbing, commercial, industrial, and HVAC markets. One of our core product offerings is valve actuators, which are used to facilitate valve operation in fluid handling systems across a wide range of industries and applications. Our experts have put together the following guide on these important devices to help readers understand what they are, what they do, what types are available, and how to select the right one for their needs.
What Are Valve Actuators?
A valve actuator is a mechanical device that moves the valve’s closure element to open and close its flow passages as needed. It can be operated manually by a human worker or automatically by an outside power source (e.g., electricity, compressed air, or compressed hydraulic fluid). Depending on its design, it can be used for on-off flow applications and/or throttling flow applications.
What Do Valve Actuators Do?
Regardless of the method of actuation, all valve actuators must perform a number of basic functions, including the following:
Move the closure element: The closure element refers to the component (e.g., the ball, disc, or plug) used to partially or completely block the flow of fluid through the valve. The valve’s actuator must be able to provide the force necessary to move and position the closure element as needed, even under demanding process conditions.
Maintain the closure element position: In addition to moving the closure element, the actuator must be able to keep it in the desired position. It may use a spring, fluid power, or mechanical stiffness for this purpose, depending on its type.
Seat the valve with sufficient torque: The actuator must generate and maintain enough torque to hold the valve in the closed position during shutoff operations.
Have a failure mode: In the event of power failure, the actuator should have an appropriate failure mode (e.g., as-is, fully closed, fully open) to ensure the system does not experience excessive damage.
Provide proper rotational capabilities: Actuators must be able to accommodate the rotational capacities (generally 90 or 180 degrees) of their valves.
Operate at the appropriate speed: Special control circuit elements can be used to regulate the cycle speed of a valve actuator. For fast cycle speeds that fall below half of the standard actuator cycle time, it is important to carefully select the valve to avoid shock-related damage to its parts.
Types of Valve Actuators / Actuation Methods
Valve actuators come in a variety of designs and configurations, each of which offers unique benefits and limitations that make it suitable for different applications. Understanding the distinctions between the various types is essential to selecting the right one for a particular use case. Below, we highlight three of the most common types of valve actuators.
Manual Valve Actuators
Manual valve actuators use hand-operated levers or wheels that engage a series of gears to open or close the valve. While they tend to be low in cost and simple to use, manual valve actuators are limited to applications in which automated or remote valve control is not required.
The types of manual valve actuators available include:
Basic levers: Basic lever actuators consist of a long handle that attaches to the valve stem to enable valve rotation.
Handwheels: Handwheel actuators consist of a large handwheel and gearbox, the latter of which increases the mechanical advantage. They are commonly used in larger valves that need higher amounts of torque to operate.
Manual valves with limit switches: Manual valves can be equipped with limit switches to convey the position of the valve to the control system.
Pneumatic Valve Actuators
Pneumatic valve actuators provide automatic or semi-automatic valve operation by converting the energy from compressed air into mechanical motion. They work by containing the air within a chamber and allowing it to expand, which creates a difference in pressure between the inside and outside of the chamber. The pressure differential energizes the air. It can then be directed out of the chamber toward the mechanical component used to open and close the valve.
The types of pneumatic valve actuators available include:
Rotary pneumatic valve actuators: Rotary pneumatic valve actuators convert the energy from compressed air into rotational motion to operate rotary valves (e.g., ball, butterfly, and plug valves). They can be classified into two main categories—rack & pinion actuators and Scotch yoke actuators.
Linear pneumatic valve actuators: Linear pneumatic valve actuators convert the energy from compressed air into linear motion to operate linear valves (e.g., gate and globe valves). They can be classified into two main categories—diaphragm actuators and cylinder actuators.
Electric Valve Actuators
Electric valve actuators use an alternating current (AC) or direct current (DC) motor to generate the torque required for valve operation. The motor is attached to the valve stem through a series of gears and controlled by a cam-activated limit switch. Together, these components allow for accurate and precise adjustment of the valve.
The types of electric valve actuators available include:
Rotary electric valve actuators: Rotary electric valve actuators convert electric energy into rotary motion for the operation of rotary valves.
Linear electric valve actuators: Linear electric valve actuators convert electric energy into linear motion for the operation of linear valves.
How to Select the Right Valve Actuator
Given the broad selection of valve actuators available, it is important to carefully research your options, so you select the one that is best for your needs. Some factors to keep in mind when evaluating whether a particular product is right for your application include:
Power source availability: Does your facility have the necessary power source to operate the actuator? If you choose to use a powered valve actuator, your facility must be equipped with the appropriate power source. For example, electric actuators need an electric motor, while pneumatic actuators need a compressed air supply.
Automation requirements: Do you want to automate valve functions? Automation allows you to monitor and control valves without having to be physically near them. While manual actuators do not accommodate automation, powered actuators do.
Application conditions: What conditions will the actuator face within the application? Regarding temperature, pneumatic actuators are suitable for use in temperatures ranging from -4–150° F, while electric actuators can operate in temperatures ranging from -40–150° F. Regarding hazardous environments, pneumatic actuators are the preferred choice since they are explosion-proof. However, electric actuators can be used if they have an appropriate NEMA-rated enclosure.
Emissions: Are you trying to minimize your facility’s emissions? Pneumatic actuators emit various levels of methane gas into the atmosphere as they operate, creating a challenge for highly regulated industries that must keep their emissions low. Electric actuators provide a zero-emissions alternative to pneumatic designs, allowing companies to comply with increasingly strict environmental regulations.
Cost: How much are you willing to pay for your actuator? Both manual and pneumatic actuators have lower upfront costs compared with electric designs. However, the higher efficiency and reduced emissions of electric actuators can provide significant long-term cost benefits in the right applications.
Quality Valve Actuators From RED-WHITE VALVE CORP.
Valve actuators play a vital role in fluid handling systems. That’s why it is important to source them from a reliable supplier. For valve actuators you can trust in your most critical applications, turn to the experts at RED-WHITE VALVE CORP. As valve technology leaders, we have the knowledge and skills to design and manufacture valve products, including actuators, that meet some of the strictest performance and quality standards. To learn more about our valve actuators, contact us today.
Posted by RWVC on | Comments Off on An Introduction to Pneumatic Actuators
What Is a Pneumatic Actuator?
Actuators convert potential energy into kinetic energy (i.e., mechanical motion) when prompted by a control signal. They are integrated into a variety of devices and systems to perform various tasks. There are many types available, each of which is suitable for different applications. One way of categorizing them is by their power source (i.e., what form of energy they use to produce mechanical motion).
Pneumatic actuators—also referred to as pneumatic cylinders, air cylinders, and air actuators—rely on compressed air for their operation. While all pneumatic actuators have the same basic components (a cylinder, ports or valves, and a mechanical element), they can vary in design; for example, rotary actuators convert energy into rotary motion, while linear actuators convert energy into linear motion.
Typical applications for pneumatic actuators include:
Packaging and production equipment
How Does a Pneumatic Actuator Work?
As mentioned above, a pneumatic actuator uses compressed air to produce mechanical motion. It does this by containing regular air, pressurized gas, or a combination of the two within a chamber and allowing it to expand. As the air/gas expands, it creates a pressure differential between the inside of the chamber and the surrounding environment, which energizes the air/gas. The air/gas is then directed out of the chamber toward a mechanical component (e.g., gear or piston), which actually performs the task.
Advantages of Pneumatic Actuators
Compared to other types of actuators, pneumatic valves offer a number of advantages.
They have a simple design, which makes them easy and, consequently, cheaper to produce.
They are highly durable and easy to maintain, resulting in lower replacement and repair costs.
They do not require electricity or ignition to operate, making them suitable for use in environments where combustion is a concern.
They can generate greater forces than electric actuators, which makes them better suited for handling heavier loads.
Types of Pneumatic Actuators
Pneumatic actuators can be classified according to a variety of design factors. For example, they can be categorized into three main varieties based on what type of mechanical motion they produce: linear, rotary, and combination.
Linear actuators are designed to produce linear motion. They use various mechanisms to perform this function, such as pistons and diaphragms. In piston-style linear actuators, the stroke length is dependent on the length of the cylinder. In diaphragm-style linear actuators, the stroke length is dependent on the stretch tolerance of the diaphragm.
Piston-style linear actuators can be further classified into single-acting actuators and double-acting actuators. Single-acting actuators rely on air pressure to move the piston in one direction and a spring to move it back to the original location. Double-acting actuators rely on air pressure to move the piston forward and back. The former has a simpler design, a smaller footprint, and lower compressed air requirements. The latter offers greater force capacities, faster operating speeds, and longer lifespans.
Rotary actuators are designed to produce rotary motion. Similar to linear actuators, they use a variety of mechanisms to perform this function. Some of the most commonly used are pistons, diaphragms, yokes, vanes. Piston-style rotary actuators offer a limited range of rotation, yoke-style rotary actuators offer up to 90 degrees of rotation, and vane-style rotary actuators offer up to and exceeding 360 degrees of rotation.
Combination actuators are designed to produce both linear motion and a limited degree of rotary motion. They are commonly used in work holding applications, where they are used for clamps that must be constantly engaged, disengaged, and reengaged to switch out workpieces.
Pneumatic Actuators From RED-WHITE VALVE CORP.
Pneumatic actuators play a vital role in many different devices and systems (e.g., in valve systems, they open and close the valve to start and stop the flow of fluid). Given their importance, it is essential to source them from a reliable supplier. Otherwise, they may underperform or fail, which can lead to loss of productivity and profitability.
Need pneumatic actuators you can trust in your critical valve applications? The experts at RED-WHITE VALVE CORP. have got you covered! We offer high-quality pneumatic actuators for valve assemblies used in industrial and commercial applications. To learn more about our product offerings, contact us today.
Posted by RWVC on | Comments Off on How Does an Electric Valve Actuator Work?
Electric valve actuators control the opening and closing of valves. They can provide either linear or rotary motion and work with different types of valves, including ball and butterfly valves. Electric valve actuators respond to prompts through remote control or centralized process control systems, which make them invaluable for managing systems that are hard to reach or spread across a large area. Process control systems can operate electric actuators from a centralized system to deliver scheduled and programmed commands, thereby allowing organizations to automate the system and improve reliability.
Overall, electric valve actuators are becoming increasingly responsive, technologically advanced, and easier to use. The following guide explains what you need to know about how these components work and what’s needed to install and use them.
Electric Actuator Components
Unlike other valve actuators, electric actuators contain motors that can convert electricity in either linear or rotary motion to open, close, or adjust a corresponding valve. Different electric actuators control various types of movement; a quarter-turn actuator, for example, will turn the valve’s mechanism 90 degrees, which is fully open.
It’s important to choose the electric valve actuator that runs on the right voltage to match your facility’s system. These systems vary depending on whether an operator uses alternating current (AC) or direct current (DC) power sources.
Some of the most popular voltage types are:
Along with the motor, actuators have other electrical components, including a limit switch, wiring, and gearing. All these parts are arranged in a compact, protective housing unit.
Torque Requirement for Electric Valve Actuators
Torque is the rotational force an actuator generates to close a rotational valve. Electric actuators can generate this force by transmitting it to the output shaft and then the valve stem. When pressure is applied to the valve stem, the valve’s orifice opens or closes.
Actuators have different levels of motor capacity (power) based on the torque they need to provide. It’s important to select actuators based on the breakaway torque a valve requires. The “breakaway torque” is how much power is needed to initiate the switch from a static open to a closed position or vice versa. It’s the highest level of torque required to operate the system.
When you’re mounting electric valve actuators in place, use sturdy, industry-standard parts. Many actuators and mounting hardware use the ISO 5211 standards for connections, which ensures various brands and components work together seamlessly.
You’ll need at least three components for mounting:
An output drive
A stem to connect to the valve head
A flange that mounts the actuator onto the valve
Various actuators require different types of flanges based on the torque and fasteners available.
How to Choose an Electric Valve Actuator
Electric valve actuators can make fluid systems safer and easier to control. They’re especially useful if you need to expand or upgrade your system and make it more complex.
Here are some parameters that can help guide your decision:
Torque: Consider the general torque and breakaway torque requirements of the system. Secondary factors that influence the torque include fluid viscosity and valve size.
Voltage Requirements: Determine the current type and intensity of the power source at the site of the actuator installation.
Valve Mounting Connection: Different flanges, actuators, and mounting environment requirements can limit your choice of electric valve actuator.
IP Rating: IP ratings, as established by IEC 60529, have different levels of protection against environmental factors such as moisture and dust.
Enclosure Protection Certification: Similarly, the protective housing and enclosures must be able to act as a barrier against the application hazards that are specific to the environment.
Fail-Safe: Integrated electric valve actuators can be programmed with automated settings that go into effect if there’s power loss, an emergency, or system failure.
Modulation: Some actuators can control the fluid flow rate, modulating it, while other allow just a ON/OFF control.
Application: The fluid material, temperature, and other factors of your intended application can also affect which electric actuator valve will work best.
Electric Actuator Valves From RED-WHITE VALVE CORP.
At RED-WHITE VALVE CORP., we serve a variety of industries by providing powerful, integrable electric valve actuators.
These industries include:
Food and beverage
Oil and gas
For more details about our exceptional craftsmanship and specs, see our electric actuator product pages: