Valve Positioners for Every Process Control Application

The Role of Valve Positioners

As a control valve accessory and the interface between the control system and valves, the valve positioner plays a vital role in ensuring reliability and optimal performance in your process control loops. Using a valve positioning device, you can adjust the valves' opening to allow for varying flow rates, from entirely on or off to anywhere in between.

Valve positioners move a valve in the right direction by increasing or reducing the actuator's air load pressure. The position of the valve stem or shaft corresponds to the setpoint from the control system.

On linear control valves, positioners mount to the pneumatic actuator's yolk or top framework. Rotary control valves mount to the end of the shaft. For either set-up, the positioner is attached mechanically to the valve stem or valve shaft, allowing the valve position to respond to the controller's demands.

Valve Positioners from Siemens

SIEMENS offers you a broad choice of positioners to ensure an ideal fit for every application. Visit this link to view a summary of their positioner offerings.

For more information, contact Ives Equipment.
877-768-1600
https://ivesequipment.com

The SIEMENS SIPART PS100 Electropneumatic Positioner

The SIEMENS SIPART PS100 electropneumatic positioners are used to control the valve or damper position of pneumatic linear or part-turn actuators. The SIPART PS100 electropneumatic positioners control the valve according to the setpoint value. A hallmark of the SIPART PS100 is its own extremely low consumption of air. Thanks to the piezoelectric technology, compressed air is only required to move the valve. In the controlled state, consumption of air is negligible.

SIPART PS100 FEATURES:

• Fast commissioning at the push of a button
• Simple operation via the display and four buttons
• Display symbols according to NAMUR NE 107
• Negligible air consumption in stationary operation
• Setting the application profile based on predefined selection options, e.g. tight-closing valve, open/close valve, small valve
• Fast response in end positions ensures short positioning times and tight valves
• Insensitive to vibrations and steam hammer
• Leakage compensation ensures a constant actual value and protects the actuator
• Only one device version for linear and part-turn actuators

SIPART PS100 INDUSTRIES:

• Power stations
• Paper and glass
• Water and wastewater
• Food and pharmaceuticals

For more information contact Ives Equipment. Call Ives at (877) 768-1600 or visit their website at https://ivesequipment.com.

The SIEMENS SIPART PS2: New Features

The SIEMENS SIPART^® PS2 electro-pneumatic valve positioner is used to control the final control element of pneumatic linear or part-turn valve actuators. It is is currently the most widely used positioner for linear and part-turn actuators in a broad range of process industries. New features have been introduced, namely improved diagnostics, additional integrated pressure sensors, a fast open/fast close function, integrated booster, easy setup, a partial stroke test, fail in place function, and valve performance tests. Watch the video to understand more.

Ives Equipment
https://ivesequipment.com
(877) 768-1600

Understanding Valve Positioners

Valve positioner on
linear control valve
(Siemens SIPART)

Industrial valves allow the flow of a process fluid through a pipe. Valves always include some type of actuation (opening/closing) device - from simple manual levers to sophisticated electric or pneumatic actuation packages. Industrial valves can act as on/off or proportioning devices to allow full flow, no flow, or modulated flow. When valves are used for modulating fluid flow, an instrument called a valve positioner is installed.

A valve positioner is used in tandem with a valve actuator, the power source to open or close the valve. Positioners precisely direct the actuator to move the valve so that a desired flow volume is achieved and maintained. The positioner does this by monitoring the process condition, comparing it to a desired set point, and then pneumatically, electrically, or hydraulically manipulating the valve orifice until the difference between the set point and actual process variable is zero.

In closed loop control systems where the final control element are valves, valve positioners are the "brains" that provide the corrective signal to eliminate process offset. Positioners enable tighter control by overcoming the realities of valve wear, imprecise calibration, and a host of other process variable challenges.

Valve positioners are used throughout the process industries including power, pharmaceutical, chemicals, oil and gas, food and beverage, pulp and paper, refining and petrochemicals, pipelines, and many other processes.

Basic Function

Diagram of typical flow control loop using valve positioner.

A valve positioner receives a signal from a controller. The controller could be part of a distributed control system (DCS), a programmable logic controller (PLC), or a discreet PID controller. The controller interprets a signal from some type of sensor, such as a flow transmitter, temperature transmitter, pressure transmitter, or other, and compares the transmitter reading to a desired setpoint. If the controller sees an offset (error), a corrective signal based on the difference, is sent to the valve positioner. The positioner then repositions the valve actuator that in turn readjusts the position of the valve, thereby changing the process condition, brining the system to to equilibrium.

Types of valve positioners:

Pneumatic Positioners

Pneumatic positioners receive pneumatic signals (3-15 or 6-30 PSIG) and proportion the supply air pressure to the valve actuator accordingly to move the valve to the required position. Pneumatic positioners are intrinsically safe and have the ability to provide a large amount of force to open or close a valve.

Electro-Pneumatic Positioners

Electro-pneumatic valve positioners are very similar to pneumatic postioners, except that they contain internal current-to-pneumatic converter (I/P). The current-to-pneumatic module receives a varying electrical signal (most commonly 4-20 mA) and converts that signal (proportionately) to a pneumatic output signal (3-15 PSIG or 6-30 PSIG). The pneumatic signal then then proportions the supply air pressure to the valve actuator.

Electric Positioners

Electric valve positioners receive an electric signal, usually 4-20 mA, 1-5 VDC, 2-10 VCD or 0-10 VDC and generally drive the motors in electric actuators. They perform the same function as pneumatic positioners do, but use electricity instead of air pressure as an input signal.

For more information on valve positioners, or any valve automation requirement, contact Ives Equipment by visiting https://ivesequipment.com or calling 877-768-1600.

Introduction to the SIEMENS SIPART PS2 Smart Valve Positioner

The Siemens SIPART PS2 is currently the most widely used positioner for linear and part-turn actuators in a broad range of process industries. The proven all-rounder offers comprehensive functionality and diagnostics, controls a variety of valves both safely and reliably, and fulfills a multitude of highly specific requirements.

For more information, visit http://www.ivesequipment.com or call 877-768-1600.

An Industrial Valve Positioner that Offers Decisive Advantages

The SIPART ® PS2 electro-pneumatic valve positioner is used to control the final control element of pneumatic linear or part-turn valve actuators. The electro-pneumatic valve positioner moves the actuator to a valve position corresponding to the setpoint. Additional function inputs can be used to block the valve or to set a safety position. A binary input is present as standard in the basic device for this purpose.

The SIPART PS2 smart valve positioner is characterized by significant advantages compared to conventional devices, such as:

• Only one device version for linear and part-turn valve actuators
• Simple operation and programming using three keys and a two-line LCD
• Automatic startup function with self-adjustment of zero and span
• Manual operation without additional equipment
• Selectable or freely-programmable characteristics
• Minimum air consumption
• Selectable setpoint and manipulated variable limiting
• Programmable "tight shut-off function"

For more information about the Siemens SIPART 2 positioner download the detailed product brochure from this link,  or visit http://www.ivesequipment.com.

Lost Plant Air a Hidden Source for Energy Savings

Save energy costs by reducing
consumption of plant air.

Industrial plant air is one of the easiest sources of power to transmit and use. It’s also one of the most costly to generate. Information from the United States Department of Energy (DOE) indicates a wide variety of factors determine the cost of compressed air. These include, but are not limited to, local electrical energy cost, efficiencies of electric motors and compressors, load factors, and service time.

Plant maintenance are becoming more aware of air leaks and the subsequent increases in cost to overcome lost power because of those leaks. One of the major culprits for lost air in a plant is the pneumatic control valve positioner and the air required to operate them. In a typical process plant, there could be hundreds of control valves. Each control valve uses a positioner to move the valve actuator, based on a set point signal from a controller.

Control valve
with Siemens SIPART

It is the control valve positioner where the greatest air consumption savings lies.

Years ago, when electricity was cheap and when valve positioners were first introduced, plant maintenance and engineering were not concerned with something called the “bleed rate” of the positioner. Over the years though, plant personnel lost track of bleed rate and pretty much forgot that a positioner is just part of the system and it operates on air. Today, a modern process facility such as a power plant, refinery, or chemical plant can have several hundred control valves with positioners. The combined air loss due to the positioner “bleed rate” can be significant.

Siemens SIPART positioners

An immediate solution to this problem is to replace the control valve positioners with modern, energy-efficient, low-bleed models. One model, the Siemens SIPART PS2 has a proven track record of providing substantial savings to large plants. In one case, a tabacco company that had 2500 positioners was planning on spending $600,000 on a new compressor to increase output. After reviewing the capabilities of the low bleed positioner and running some tests, the plant decided to implement a plan for replacing the positioners which mitigated the need for a new compressor.

The significant change in technology came with the adoption of the adoption of a piezo ceramic valve block in low bleed positioners. Traditional positioners used an I/P and spool valve which both leaked air. Over time the leaks from these two parts is significant.

Could you and your plant be in the situation where lost energy efficiency through leaky positioners is costing big bucks? If you’re even the slightest bit concerned, call in an applications expert now for a system review.