The newly developed Quick Exit (QE) and Pressure Fall Back (PFB) tools are new offerings in the smart positioner market.
The Quick Exit tool is designed to help improve the performance of anti-surge valves, and allows the positioner to be even more reactive when opening the valve from a cut-off position.
The Quick Exit tool means that when the forecast option is enabled on the system, that with any potential opening of the valve, the positioner will maintain the valve in a closed and secured position while partially depressurising the actuator’s chamber (starting off from cut-off position). This way, it is possible to have, if requested, a quicker opening as less air will need to be evacuated.
Other notable features include: dead time of less than 50%; hysterisis of 0.5%; and available for FasTrak and QuickTrak positioners.
When the Pressure Fall Back is enabled, the positioner moves the actuator to the requested position even if the linkage between the positioner and the actuator has been lost. Therefore, if there is a position error greater than 5% for more than 10 seconds, or when the positioner is outside the position range, the positioner reads the pressure value related to the requested position dictated by the offset map.
Once this state is reached (or any other pre-determined safety position requested) the mechanical feedback can be adjusted by operators. This tool is applicable only on spring return actuators. PFB can be used manually, or automatically depending upon the need.
Caption: The Quick Exit software tool allows the positioner to be even more reactive when opening the valve from a cut-off position.
Image courtesy of IMI STI