Analyzer overview – Hach-Lange POLYMETRON 9240 Operator Manual User Manual
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Analyzer Overview
3.6.2.1 Search stability set to NO - Fixed measurement mode
As the cycle and on-line measurement times defined by the user are fixed and identical for each
channel, they need to be long enough to have an efficient rinsing step for all configurations in
order to achieve accurate measurements.
The rinsing time has to be chosen from either the channel with the highest or the lowest sodium
concentration.
The following table shows the “recommended” rinsing times to guarantee consistent and
accurate measurements. Refer also to
for the “best performance” timings.
Example:
Channel 1: 200 ppb
Channel 2: 0.1 ppb
Channel 3: 5 ppb
Channel 4: 50 ppb
Sequence: 1 2 3 4 * * * * * * * *
In this example, and based on the table above, the best choice for the rinsing time is to choose
at least 45 minutes. If an on-line measurement time of 5 minutes is chosen, a cycle time of 50
minutes will be used to ensure the accuracy. In this case, the analyzer will spend 50 minutes on
each channel before passing on to the next.
Table 2 Recommended rinsing times
Previous
channel
Current channel
T°
Recommended rinsing time
to reach accuracy
1
→ 0.05 ppb
25°C
35 min
0.05
→ 1 ppb
25°C
30 min
5
→ 0.1 ppb
25°C
35 min
0.1
→ 5 ppb
25°C
20 min
50
→ 0.1 ppb
25°C
40 min
0.1
→ 50 ppb
25°C
15 min
200
→ 0.1 ppb
25°C
45 min
0.1
→ 200 ppb
25°C
15 min