Hach-Lange POLYMETRON 9240 Basic User Manual - Manual (Page 10)

6. The flow rate for each channel should be 6 to 9 L/hour.
7. Using a screwdriver, regulate the channel’s sample flow (No. 3 in
Figure 1 on page 6) by turning
counter-clockwise to increase the flow rate or clockwise to decrease the flow rate.
8. The process is repeated until the flow is correctly regulated for the channel. At this point select
OK.
9. The system then allows you to regulate the next channel until all flow rates have been set for the
configured channels.
10. Once all flow rates for the configured channels have been set, an Action completed message
will be displayed. Select Esc to exit.
Sample pH conditioning check
Non-cationic applications
1. Install a calibrated pH sensor in the center position of the measurement chamber which is
normally used for the ISE sodium electrode (No. 1 in Figure 1 on page 6).
2. On the analyzer, press Start on the main menu to start the measurement process.
3. For each channel, check that the pH value of the sample after conditioning is greater than 10.5. If
not, check the quality of the conditioning product used.
Cationic applications
1. With a calibrated pH sensor, measure the pH of the sample for each channel outside of the
analyzer.
2. The analyzer measurement sequence will be factory set depending on the number of configured
channels (e.g. 1 2 3 4 * for a 4-channel analyzer or 1 2 * for a 2-channel analyzer). Verify this
sequence is correctly setup (see
Sequence on page 18 for more details).
3. Set the following measurement timings (see Measure steps on page 15):
• CYCLE TIME to 11 min
• ON LINE MEAS to 8 min
• SEARCH STAB to No
4. For each channel, determine the gas injection time ratio depending on the sample pH. Enter this
value into the analyzer as described in Total gas/water ratio (cationic applications only)
on page 15. The standard values are:
• pH = 2.0 - Tgas/Twater ratio = 180%
• pH = 2.3 - Tgas/Twater ratio = 80%
• pH = 2.6 - Tgas/Twater ratio = 50%
• pH = 2.9 - Tgas/Twater ratio = 30%
• pH = 3.5 - Tgas/Twater ratio = 15%
• pH = 4.0 - Tgas/Twater ratio = 10%
5. Install the same pH sensor in the center position of the measurement chamber (No. 2 in Figure 1
on page 6).
6. On the analyzer, press Start on the main menu to start the measurement process.
7. For each channel, measure the pH in the conditioned sample to check if the pump ratios are
efficient enough to obtain a pH of around 11.0. If necessary, update the ratio to maintain a final
constant pH of 11.0 ± 0.2.
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