Monday, September 30, 2019

Electropneumatic Valve Positioner Offering Precise Control, Smooth Operation, and Fast Response

Kinetrol EL
Features of the Kinetrol EL positioner (click on image for larger view).

The Kinetrol EL is one of the valve automation industries best performing electro-pneumatic positioners available. It combines the precision and adaptability of a digital electronic control circuit with the smoothness and efficiency of Kinetrol's proven proportional servo valve, to give the best available 4-20mA positioning performance from rotary pneumatic actuators.

To compliment this unbeatable performance, the EL combines the easiest available setup procedure, easiest access to all functions and options, easy connectivity, and a compact all-metal housing, unique easy-set isolated angle retransmit, and limit switch options inside the same enclosure.

The EL positioner is designed to smoothly and precisely drive a rotary or linear actuator to a position set by the 4-20 mA input signal, and then accurately hold it there until the signal changes.

Inside the EL, a microprocessor in the loop powered 4-20 mA positioner circuit reads signal via one channel of a 12-bit A-D convertor, reads the position voltage from tie pot via the second channel of the A-D convertor, and compares the two. If an error between desired position and actual position exists, the EL changes it's output to the servo valve in order to drive the actuator in the direction required to eliminate the error.

In sync with the movement of the actuator, the feedback pot voltage changes, and the microprocessor continually calculates how to adjust the servo valve in order to guide the actuator accurately into position. Because the servo valve is a fully proportional device, it can be adjusted precisely and smoothly to slow the actuator to a stop exactly at the required position.  Programmed in the microprocessor is an advanced algorithm that allows this critical dynamic valve adjustment to be made correctly, giving optimal results with any actuator/load combination. Slow or fast responding, high friction or low friction, high inertia or low inertia, all can be optimized by PGAIN and DAMP parameters via the positioner circuit pushbuttons. The 12-bit A-D conversion gives the amazing resolution of approximately 1/40 of a degree angular.

For more information, contact Kinetrol USA by calling 972-447-9443 or visit their web site at https://kinetrolusa.com.

Monday, September 16, 2019

Oil Refinery Chooses Kinetrol for Fast Closing 6" Ball Valve

Fast Closing 6" Ball Valve
6" ball valve with failing actuator.
A Midwestern oil refinery was using a 6" ball valve with a cylinder actuator in a fast closing application. The ball valve was required to close in under 1 second with a duty cycle of 8 operations per day. Unfortunately, the cylinder actuator response became increasingly sluggish over time due to internal component wear. The customer tried replacing the cylinder actuator with the same model, but it too developed the problem in under a year.

Actuator for Fast Closing 6" Ball Valve
The specified Kinetrol actuator and
high Cv solenoid valve.
The local Kinetrol Distributor Sales Representative and Kinetrol Regional Sales Manager worked together to engineer a better solution. They knew the Kinetrol rotary spring unit would provide enough torque to close the valve quickly, but the concern was with the actuator exhaust venting.

After calculating the air flow characteristics of the actuator and  the response time of the spring, they knew the critical element was finding a high flow capacity solenoid valve. It needed to be capable of dumping the actuator air quickly enough to close the actuator in under 1 second.

The result was a recommendation to use a Kinetrol model 147-120-4900L spring return actuator with a third party, high Cv (9.7), solenoid valve.

Once installed the 6" ball valve and Kinetrol assembly worked perfectly and, at the time of this writing, has been in service for 3.5 years, operating with no downtime and maintaining the under 1 second closing requirement.

For more information, contact Kinetrol USA. Call 972-447-9443 or visit https://kinetrolusa.com.