Record Keeping; Process Trending - ProMinent DULCOMETER PH-501 Assembly And Operating Instructions Manual

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6.2.4 Record Keeping

An essential component of quality control in any facility is sound record keeping. A log book
covering the entire treatment system performance should be maintained, updated, and readily
accessible to all operators. The log book should be used to record observations, set point
alterations, and unusual conditions.
For each wet chemistry parameter analysis, a separate work-sheet has to be prepared. Work-
sheet data for at least the previous year should be kept for possible consultation.
The second step in quality control is to train all operators to follow an established procedure for
each test. Identical samples should be periodically tested for any parameter by different
operators, and the variability among results should be compared. Consistent variability in results
may lead to the technique improvement of operators.
Duplicate analysis of a sample should also regularly be done. And, split samples should
regularly be sent to an outside accredited laboratory and analysis results should be compared
with those done in-house.
In addition to summary sheets, it is highly recommended that data should be entered into
prepared Excel spread-sheets. Spread-sheets greatly aid in the data presentation and
manipulation, and would be of immeasurable value when report writing is required.

6.2.5 Process Trending

Other than pre-planned process changes or major upsets, process modifications should be
based on trends shown in the process data. A trend is nothing more than an indication of real
change in a process parameter over time. A trend chart is simply a graph of data being trended.
As the graph changes, upward or downward trends are detectable. Smoothing trends by
graphing the 3-, 7-, or 30-day average of the data allows the trend to be shown more clearly.
Because the individual data point may be questionable, the actual value of data point are less
important compared with the trend regarding the process monitoring.
Trend graphs are a part of the Excel data spread-sheet; the operator can trend and analyse
many parameters in just a few minutes in order to assess process performance.
When a trend is identified, its indication to the process can be evaluated, and corrective action
may be carried out, if needed. Statistically, the more data points there are in a trend chart, the
more reliable the trend.
newterra O&M Manual 89
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