Installation, Operation and Maintenance Manual
September 2019
MAN720_IMVS2000v2_IOM Rev. 6
Section 5: Working Principle
Working Principle
To use the IMVS2000v2 at its own best, it is suggested to perform the Baseline and Maintenance
Signatures in the following conditions:
•
pressures and position stable
•
valve in its “normal” working position (ex. Open position for a “fail to close” actuator)
Opening and Closing FST (Digital Input)
5.1.3
Opening and Closing FST (External Source)
It is possible to open and close the valve/actuator through the Digital Inputs of the IMVS2000v2.
The IMVS2000v2 reads the status of the Digital Input and controls the SOVs to move the valve
actuator (see Section 5.2.2 for details).
The IMVS2000v2 records all the complete Opening FST and Closing FST (graphs are stored into the device
memory) and it is possible to compare the measured pressures and times with the ones of the Baseline
Signature, to obtain a relevant diagnostic (see Sections 5.2.7, 8, 5.1.6, 5.1.8 and 5.2.8.1 for details).
To open and close the valve/actuator through the IMVS2000v2, it must be correctly connected and
configured and it must be able to control the valve/actuator system. It is possible to store the FST
data, only if a Baseline Signature is already successfully executed.
To use the IMVS2000v2 at its own best, it is recommended to open and close the actuator when
pressures and position are stable (see Section 5.2.8.1 for details).
The IMVS2000v2 continuously monitors the position of the valve/actuator. If a complete Opening
FST or a complete Closing FST is performed without using the IMVS (i.e. external SOV not controlled
by the IMVS2000v2), the device records the graph of the FST.
The data of this kind of FST are not compared with the ones of the Baseline Signature.
It is possible to store the FST data, only if a Baseline Signature is already successfully executed.
Device, the record of is inhibited for a time equal to (“B. Op. B. T.” + “B. Op. T. T.”, “B. CL. B. T.” + “B.
Op. B. T.”)*1.2, for avoiding false registrations.
5.1.4
PST
There are two different types of PST:
•
Baseline PST
•
Manual PST
To perform the Baseline PST and the Manual PST, the IMVS2000v2 must be correctly connected and
configured and it must be able to control the valve/actuator system.
The Baseline PST can be performed only if a Baseline Signature is already successfully executed.
The Manual PST can be performed only if a Baseline PST is already successfully executed.
The Baseline PST and the Manual PST consist of one partial closing or partial opening stroke, when
the valve/actuator reaches the PST setpoint (configurable) it comes back to the starting position.
The PST is “automatically managed by the IMVS2000v2; at the end of the operation the valve/
actuator system comes back to the starting position.
During the execution of the Baseline and Manual PST the Digital Inputs status is not considered.
A new Baseline PST cancels all the stored Manual PSTs data.
The Baseline PST allows to record the reference times and pressures of the partial opening stroke or
of the partial closing stroke.
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