Smart valve positioner saves time and power

Edited by the Engineeringtalk editorial team Mar 8, 2002

Heap and Partners has developed Storm, a new smart valve positioner, designed to offer simple setup yet sophisticated control.

Heap and Partners has developed Storm, a new smart valve positioner, designed to offer simple setup yet sophisticated control.

The market for smart positioners is rapidly growing as conventional units are unable to offer the flexibility or control options required by today's increasingly advanced process technology.

Some positioners, however, offer levels of sophistication many users simply don't need or use.

Certain positioners require the use of a fieldbus for operation, yet the majority of valve users have not introduced fieldbus communications and rely on the industry standard 4-20mA signal for control.

Others have an overly complex user interface requiring constant reference to manuals.

This unnecessary sophistication greatly increases the installation costs and set up times.

Using its knowledge of the process industry and positioners Heap and Partners set out to design a product that was simple to use yet offered all the advantages of smart positioners.

Heap and Partners decided that the basic unit should be quick and easy to set up and the interface simple and intuitive, while the user would still be able to specify advanced options and fieldbuses.

The result was Storm, a smart valve positioner.

The intelligence is provided by a microprocessor configured by an integrated LCD display and three-button keypad.

To offer precise control, advanced piezo-pneumatic technology from Hoerbiger Origa was used.

At the heart of Storm are its auto-calibration routines.

An innovative direct drive potentiometer with torque limiting clutch allows Storm to be mounted and calibrated quickly, eliminating the need for time-consuming alignment procedures.

Storm then continues to set up the valve travel, control parameters and auto tunes the PID algorithm to give optimum performance tailored to the specific valve and actuator package.

A typical auto set-up will take just 3min.

Compared with conventional positioners this can offer a time saving of up to 1h on a typical valve installation.

A PID control algorithm is used to improve control performance.

The three-term control improves accuracy and response time whilst eliminating overshoot.

For the advanced user Storm can be quickly changed to almost any configuration through the keypad.

There are various options available including reverse acting, split range, split travel, and either pre-set or custom characteristic curves.

The user also has access to the PID settings for fine adjustment.

A number of diagnostic functions can be accessed allowing the user to check for changes in travel and response time.

This can be used for early identification of potentional valve failure and production of preventive maintenance schedules.

The enclosure for Storm was considered to be an integral part of the design.

It was essential that the enclosure was capable for operation in the harshest of environments and provides excellent chemical resistance.

The enclosure is manufactured from PPS and all external fittings and seals are in stainless steel and viton.

This has enabled Heap and Partners to certify the enclosure submersible to IP67 and 1000 hour salt spray tested.

The piezo technology supplied by Hoerbiger Origa has provided Storm with an ideal pneumatic positioning system.

The quick response time has enabled a fully digital control scheme to be implemented which increases accuracy.

A unique manifold design eliminates static state air bleed.

The manifold is extremely efficient in its air consumption with the digital control using measured pulses of air only when positioning.

Once in position the airflow is shut off completely.

This eliminates the wastage of compressed air found on conventional positioners offering the user considerable cost savings, which has been estimated by one major chemical company as up to GBP 150 per year.

In addition the low power characteristics of the piezo valves, 0.000014mW, combined with micro-power circuit design has enabled Storm to be loop powered from a 4-20mA signal with a voltage drop of 5V.

Also, Storm has been certified intrinsically safe to Eexia IIC T5 for use in hazardous areas.

This makes Storm the only Zone 0 certified digital positioner on the market today.

(This was Engineeringtalk's Top Story on 7 March 2002).