Teledyne 6750 operating instructions Benchmark/Auto-Validation

Total Organic Carbon Analyzer Theory of Operation

2.4.5.1BENCHMARK/AUTO-VALIDATION

Benchmark is the European NAMUR* specified validation technique, whereby on command a chemical calibration standard is automatically introduced to the analyzer and the response is compared to the previous analyzer calibration. If the response falls within a certain specified limit, the computer/output indicates “Benchmark Passed”. If the response falls outside specified performance limits, either a “Maintenance Request” or a “Fault” alarm is activated, depending on preset tolerances.

Thus, in cases of process spills, when the analyzer performance is questioned, Benchmark can rapidly and automatically validate analyzer performance. It eliminates time consuming and unnecessary recalibration cycles, which take the analyzer out of service just when it is most critically needed. Benchmark may be on-demand, or operator programmed for designated day and time activation on a repetitive basis.

On command (manual or automatic by selection of day/time), the combination of valves V3 and V4 divert the sample and introduce a liquid calibration solution to the analyzer. This is the same calibration solution used to previously calibrate the analyzer, “end-to-end”. If the TOC value from the calibration solution falls within a limit (generally set at 5% of the previous calibration), then “Benchmark Passed” will be displayed and remotely reported. If the TOC “Benchmark” solution falls outside the set tolerance, then a “Benchmark Failed” message and a “Maintenance Request” are reported.

2.4.5.2AUTO-CALIBRATION

On command (manual or automatic by selection of day/time), the combination of valves V3 and V4 alternately introduce D. I. water for a “Zero” calibration and the “Span” solution. The computer then resets the analyzer to the new calibration values.

2.4.5.3AUTO-CLEANING

On command (manual or automatic by selection of day/time), the combination of valves V3 and V4 operate to introduce a “cleaning” solution, depending on the chemical constituents of the sample. Acid or persulfate is generally used.

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