A-27
Appendix A Maintenance and Troubleshooting of this Device
The procedures stated in “Acquisition of index values under normal conditions” and “Clogging
simulation test” refer to the following parameters and process variables.
Pressure Frequency Index
Press Freq Index Max
Press Freq Index Min
Standard Deviation
Standard Deviation Max
Standard Deviation Min
Press Freq Calc PV High Limit
Press Freq Calc PV Low Limit
The standard deviation values are not directly used to diagnose clogging, but it may be necessary to
refer to them during parameter adjustment. Therefore, it is recommended that they be collected at
the same time as the pressure frequency indexes.
A4-4 Configuration procedures
This section describes the configuration procedures in order.
A4-4-1 Preparation
Before starting configuration, initialize the parameters.
Procedure
(1) Set Press Freq Index Sensor Selection to “DP, 120 ms.”
(2) Set Press Freq Filter Constant to “0.15.”
(3) Set Press Freq Calc PV High Limit to “Upper Range Value.”
(4) Set Press Freq Calc PV Low Limit to “Lower Range Value.”
(5) Set Press Freq Index Alarm Use to “Disabled” (operation off).
A4-4-2 Acquisition of the index values under normal operating conditions
Obtain the index value under normal operating conditions without clogging in the connecting
pipe. The collected pressure frequency index and standard deviation values are used to judge the
possibility of diagnosis and to adjust the parameters in later steps.
Procedure
(1) Check that the connecting pipe is operating normally. When a valve such as a manifold valve is
attached to the connecting pipe, check that the pressure can be measured.
(2) Execute Reset Press Freq Index and Reset Standard Deviation. Note that after Reset Press Freq
Index is executed, the correct values for Pressure Frequency Index, Press Freq Index Min, and
Press Freq Index Max cannot be obtained for a short period of time. After Reset Press Freq
Index has been executed, wait until the first index calculation is completed.
(3) Wait for at least 30 minutes, and if possible one hour.
(4) Obtain the values for Pressure Frequency Index, Press Freq Index Min, Press Freq Index Max,
and the process variable, and record them.
(5) Obtain the values of Standard Deviation, Standard Deviation Min, and Standard Deviation Max
as reference values, and record them.
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