| Installation, Operation & Maintenance Manual |
MSL600 | IP262/Z0, Rev. AB |
February 2012 | |
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7.9.4Municipal 2 parameter P640
Only one specific parameter, P640, needs to be adjusted when the Municipal 2 algorithm is selected.
Industrial blankets are typically much denser and more substantial than municipal sludge found in a conventional wastewater plant. For this reason, the echo profile from an industrial sludge typically only displays one distinct echo.
7.9.4.1Threshld Offset – P640
The echo from the blanket will produce a signal which is visible above the electronic noise floor on the echo profile display.
The threshold offset parameter is the offset of the threshold which the user wishes to set above the noise floor. Both the noise level, D834 and the threshold offset are expressed as a % of full screen.
The noise level can be viewed as a diagnostic parameter from the monitor menu. The first point in the echo profile which exceeds the threshold level is determined by the algorithm to be at the blanket level.
Remember that;
Threshold level = Threshld Offset (P640) + Noise Level (D834)
When setting this parameter, remember that the echo amplitude can get larger or smaller over a period of time during normal operation of the system. This is because the consistency of the sludge varies with time and position in the settling tank as the bridge rotates over it.
Floating debris close to the transducer can give echoes which will exceed the threshold level. It is suggested that in this case the blanking distance, P623 be extended to include this region in the echo profile.
The default value is 30%.
Parameter values:
Default | Min | Max |
30 | 0 | 100 |
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