Appendix B - Multi-Stream Sodium Wet-Section; Multi-Stream With Flowmeters Fitted; Multi-Stream With No Flowmeters Fitted - ABB Navigator 500 Series Operating Instructions Manual

Navigator 500
Sodium analyzer
Appendix B – Multi-stream sodium wet-section
The sample streams enter the bottom of the wet-section (via flow meters if fitted), diverting sample to the sample valve manifold
(mounted on the top of the bracket) and the calibration valve manifold to the constant-head unit. The solenoid valves are used to
switch between sample streams. If a stream valve is energized the sample flows up to the constant-head unit via the manifold and is
measured by the wet-section. If a stream valve is de-energized the sample is diverted directly to drain.
The sample time is the duration of time between the stream valve energizing and the corresponding stream value updating on the
transmitter. Between updates the reading on each stream is held. The sample time is the same duration for all streams. The sample
time is normally set to 15 minutes, but may need to be increased if the difference is sodium concentration between streams is
significant or if an accurate low concentration reading is required. Table B.1 shows suggested sample times for different sodium
concentrations.
Sodium concentration:
previous stream (ppb)
0.1
0.1
5
50
5
50
50
500
Table B.1 Recommended sample times for sodium concentration values
The stream sequence is normally set to sample each stream in turn – for example, on a three stream wet-section the sequence would
be set to 1, 2, 3. However, greater priority could be given to a particular stream (for example, stream 1) by programming the
sequence 1, 2, 1, 3 or 1, 1, 1, 2, 3.
If only 1 stream is enabled the wet-section functions as a single-stream version and continuously measures the sodium
concentration. This is useful for troubleshooting as there is a concentration update every second.
B.1 Multi-stream with flowmeters fitted
The flow rate measurements are used by the wet-section PCB to determine whether there is enough sample flow to measure each
stream – it is advisable to ensure at least 100 ml/min of sample is supplied to each stream. The wet-section does not sample a
stream if the flow rate drops below 50 ml/min.
If the sample flow rate is measured to be less than 50 ml/min, the Flow Error diagnostic activates for that stream (see page 73). If the
sample flow rate drops below 50 ml/min while the stream is being sampled, the concentration value is not updated and the wet-
section starts to sample the next available stream in the stream sequence.
If all streams are below the required flow rate of 50 ml/min, the No Samples diagnostic is displayed (see page 74). This situation
should be avoided. If the wet-section is going to be without sample for extended periods the Shutdown Procedure should be
followed – see Section 8.5, page 63.
B.2 Multi-stream with no flowmeters fitted
If during the sampling period the stream is detected to be Out of Sample via the Out of Solution pressure switch, the No Sample
diagnostic activates for that stream, the stream valve is de-energized and the stream value is not updated (see Appendix A.1,
page 72). The next enabled stream in the stream sequence is then sampled.
If all streams are detected to have no sample the No Samples diagnostic is displayed and the wet-section searches for an available
stream. This procedure energizes each valve in the stream sequence for up to 14 seconds; this continues until a stream is detected
to be in sample, it then continues to sample that available stream. The No Samples situation should be avoided. If the wet-section is
without sample for extended periods, follow the shutdown procedure – see Section 8.5, page 63.
OI/ASO550–EN Rev. G
Sodium concentration:
current stream (ppb)
5
50
50
50
0.1
0.1
5
50
Appendix B – Multi-stream sodium wet-section
Recommended sampling
times (minutes)
20
15
10
10
35
40
10
10
Upscale / Downscale
change
Upscale
Upscale
Upscale
Upscale
Downscale
Downscale
Downscale
Downscale
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