How to Install the Kinetrol AP Pneumatic Positioner

This video describes how to install a Kinetrol AP pneumatic positioner on a Kinetrol vane actuator.

The Kinetrol AP positioner moves an actuator to a position set by a 3-15 psi control signal and holds it there. It is designed to drive a rotary or linear actuator to a position set by a 3-15 psi (0.2 to 1.0 bar) signal and hold it there until the signal changes.

When a signal pressure is applied to the diaphragm it moves the force balance lever clockwise against the tension of the feedback spring. This moves the spool valve, supplying air pressure to one side of the actuator while exhausting trapped air from the other side.

The feedback shaft follows the movement of the actuator and turns the cam counter clockwise, pushing the cam follower and increasing the tension on the feedback spring until it balances the forces on the diaphragm and moves the spool valve to its hold position.

The input signal and desired position is determined by the cam profile. A cam giving 0-90° output movement linearly proportional to a 3-15 psi (0.2-1.0 bar) signal is standard, and almost any desired characteristic can be supplied to order; if it cannot be found in the list of existing options contact Kinetrol.

For more information, contact Kinetrol USA by calling 972-447-9443 or visiting https://kinetrolusa.com.

Wishing You a Great 2019!

Happy Holidays from Kinetrol USA

Happy Holidays from everyone at Kinetrol USA. We hope 2019 is a great year for you!

Why Do Kinetrol Actuators Last So Long?

Kinetrol actuators are known world-wide for their extremely long service life, even in harsh environments. Here are a few reasons why.

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972-447-9443

Kinetrol Actuators Protect People and Property with Reliable Performance in Chemical Plant Fire

The Kinetrol actuator is completely
unrecognizable,  having been melted in a fire.

A chemical plant in the Southeast USA that manufactures PTA (purified terephthalic acid) experienced a compressor house fire, causing extensive equipment damage and shutting down production for months.

The building houses a $30 million dollar compressor that supplies process air to reactors to begin the PTA manufacturing process.

As part of the safety system, (2) two 6" class 150 high performance butterfly valves with Kinetrol 097-120 and open/closed limit switches were installed on process air lines of one production unit.

During the fire, the two Kinetrol actuated valve assemblies performed exactly as required, shutting the valves tightly and keeping them shut even after the heat of the fire completely melted the actuator housings.

Closer view.

The actuators had been in service one year at the time of the fire.  Unlike many other Kinetrol actuator applications, these were not chosen for their high cycle capability,  nor for their long service life. In this application Kinetrol was chosen for their absolute reliability in critical situations.

For more information, contact Kinetrol USA by calling 972-447-9443 or by visiting https://kinetrolusa.com.

Kinetrol USA Thanks and Salutes Our Veterans. Never Forget.

Valve Failure Modes

Failsafe spring lever on ball valve.
(Kinetrol)

An important design parameter of a control valve is the position it will “fail” to if it loses motive power. For electrically actuated valves, this is typically the last position the valve was in before loss of electric power. For pneumatic and hydraulic actuated valves, the option exists of having a large spring provide a known “fail-safe” position (either open or closed) in the event of fluid pressure (pneumatic air pressure or hydraulic oil pressure) loss.

Available Failure Modes

Valve fail mode may be shown in instrument diagrams by either an arrow pointing in the direction of failure (assuming a direct-acting valve body where stem motion toward the body closes and stem motion away from the body opens the valve trim) and/or the abbreviations “FC” (fail closed) and “FO” (fail open). Other failure modes are possible, as indicated by this set of valve symbols:

In order for a pneumatic or hydraulic valve to fail in the locked state, an external device must trap fluid pressure in the actuator’s diaphragm or piston chamber in the event of supply pressure loss.
Valves that fail in place and drift in a particular direction are usually actuated by double-acting pneumatic piston actuators. These actuators do not use a spring to provide a definite fail mode, but rather use air pressure both to open and to close the valve. In the event of an air pressure loss, the actuator will neither be able to open nor close the valve, and so it will tend to remain in position. If the valve is of the globe design with unbalanced trim, forces exerted on the valve plug will move it in one direction (causing drift).


Reprinted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.