The Advantages of Torsion Springs for Pneumatic Actuators

Kinetrol uses a torsion spring
as the motive force for
their actuator spring return.

Torsion springs, or clock springs, are helical shaped springs that exert a torque or rotary force. They are one of the the oldest forms of flat springs and one of the most common type in use today because of their simplicity and reliability.

Torsion (clock) springs posses a natural tendency to expand, producing a cumulative torque that increases as the spring is wound tighter. Both ends of the torsion spring are attached to other, separate components. When one component rotates around the center point of the spring, the spring will increasingly try to return to the original state.  When a torque is applied to a spiral torsion spring, an angular displacement is created between the first and second loading points. The coil then deflects (tightens), and the spring material is placed under stress, which in turn exerts a linear rotational "output" torque.

An internal view of the
 clock spring. You'll note
similarities with the
Kinetrol spring return unit.

Practically speaking, spiral torsion springs allow for lower torque loss, lower torque stress, and much greater reliability for use in valve and damper actuation.

Advantages of the torsion spring:

• High torque delivery per unit of deflection
• Low cost
• Compact
• Reliable
• Adjustable

Epoxy Stove Enamel Finish: A Kinetrol Advantage

Kinetrol actuators are well-known for their bright yellow, epoxy stove enamel finish. This coating is engineered to protect the exterior of their pneumatic actuators and accessories. But what is "epoxy stove enamel"?

Epoxy stove enamel is a high quality stoving finish that provides excellent adhesion to a substrate. Epoxy stove enamel forms a very hard, abrasion resistant, chemical and solvent resistant coating that stands up to many extreme environmental conditions. Epoxy stove enamel finish provides high level chemical/corrosion resistant qualities, and is used often in applications such as machinery, industrial equipment, and heavy duty transport machinery.

Kinetrol actuators are engineered specifically for high-cycle, dirty, and corrosive applications. The combination of epoxy stove enamel finish and stainless steel external hardware provide Kinetrol actuators outstanding protection from dirt and harmful chemicals.

Kinetrol USA
https://kinetrolusa.com
972-447-9443

Who makes the most reliable industrial valve actuator?

With millions of actuators performing reliably around the world, the Kinetrol vane actuator's outstanding cycle life, smooth and precise movement, and environmentally rugged design makes it the best choice for all of your valve actuation needs.

https://kinetrolusa.com

Consider Space and Fit as a Cost Driver When Applying Actuation to Your Valves and Dampers

Being creative with the design and layout of automated valve packages, and paying attention to space, has significant impact on the total life-cost of an automated valve (or damper) package. Evaluating the footprint available, and then choosing components that will allow for simple installation and continued ease of maintenance, will pay dividends over the long term. Always plan your valve and damper automation systems with ample space for access to tools and service personnel.  Don't burden your maintenance staff with an over complicated or nightmarish actuation system that takes hours of preparation just to do routine maintenance. Also consider that easier access many times means greater safety.

Kinetrol pneumatic actuators, spring modules, and positioners are engineered with this in mind. Their efficient actuator design provides more torque in a smaller package and their bolt together, modular configuration, provides very significant space savings. The result is more power in a smaller space, along with easy access, and quick change-out.

Consider Space When Applying Actuation
(click for larger view)

As you can see from the image above, electrohydraulically powered valves and dampers (left) require pumps and motors. Pneumatic cylinder operated valve and dampers require mounting fixtures, linkages, and additional tubing. But you'll note the Kinetrol actuator and positioner (center) provides mounting directly to the valve/damper shaft. The automation is done cleanly and takes up substantially less space.

Which would you rather service?

Pneumatic Valve and Damper Actuators Designed to Stand Up to the Cement Industry

Cement silos.

Cement plants take a harsh toll on equipment such as valves and actuators. Abrasive material is involved from the beginning to the end. Materials handled are often dusty and cause severe abrasive wear of equipment. The movement, blending, storage, and transport of limestone, shale, iron ore, and clay wreaks havoc on the life expectancy of process equipment. Additionally, corrosion issues in cement plants are frequent and costly.

Because of their reliability and ruggedness, Kinetrol rotary vane actuators are used in many processes across a cement plant. These applications include vehicle unloading, silo discharge, air cooling dampers, distribution, bagging and emissions control.

You can download a PDF that outlines where vane actuators are used in all areas of cement production here, or you can read the embedded document below.

Kinetrol Vane Actuators in the Cement Industry from Kinetrol USA

Industrial Valve Actuator Types

Lever actuator
(with failsafe  spring return)

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.

Manual

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

Gear operator
(attached to pneumatic actuator)

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

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
(attached to pneumatic actuator)

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.

Contact Kinetrol USA for any valve actuation challenge. They can be reached at https://kinetrolusa.com or by calling 972-447-9443.

Pneumatic Valve Actuator Assembly Designed to Prevent Water Hammer

Kinetrol vane actuator and
dashpot assembly

Water hammer occurs when the flow of fluid in a pipe rapidly changes. The result can be very high pipe pressures, mechanical stress on pipe supports, and possible reversal of flow. If not controlled it can cause pipe bursting, broken pipe supports and joint leakage.

The "hammering" is due to a pressure wave created by the instantaneous change in fluid velocity when a valve is suddenly closed or opened. Controlling valve closure time is one of the most economical ways to minimize water hammer. To do this efficiently, while still meeting the process requirements, the use of a variable speed mechanism to control valve stroke is used. One unique, economical and space savings approach is to use a pneumatic vane actuator coupled with a rotary damper (or dashpot).

Rotary dashpots are precision fluid damping devices which give a smooth resistance to shaft rotation which increases with angular velocity.

In this case, a pump station in the USA was having repeated problems with a large, open reservoir hydraulic actuator used to dampen valve opening and closing.  It was overly cumbersome and costly to maintain.

In its place, the pumping station installed Kinetrol Size 14 double acting actuators with digital speed controllers and Kinetrol LJ rotary dampers (with through-shafts to facilitate position feedback) installed on 12” Pratt butterfly valves.

The addition of the bi-directional, sealed dashpots smooth the normal travel, damp any valve flow induced disc oscillations, and provide at least 40 seconds travel time on air and/or electrical power failure.

Using pulsed outputs with programmable delay between steps, the actuators provide a 10 minute opening & closing time for the full 90 degree travel. The system is adjustable between 3-15 minutes with less than one degree increments., and other opening and closing ranges are available.  The actuators use fail-free logic, but fail-hold & fail-safe are available.

These assemblies were commissioned in early Fall of 2017 and are working very well. Their use will be replicated at other pump stations operated by the same customer.

This open reservoir hydraulic actuator was huge and a maintenance headache.