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...4 LIQUID HANDLING SECTION
Start of Sequence
SV4
Energized
SV5
Fig. 4.4 Color Compensation Timing Sequence for Single Stream Instruments
4.3 Multi-Stream Operation
Between two and six streams can be fitted to the multi-stream
version of the monitor. The front panel controls remain the
same on all versions.
The monitor samples the streams in the sequence specified on
Programming Page 3.3 (see appendix A). The stream
sampling period, i.e. the duration the monitor spends on each
stream, is normally set to 12 minutes. However, the reading,
taken after a further six minutes, is used to update the display
and current output for that particular stream. This takes
advantage of the eight minutes 'dead' time of the monitor in
reducing the overall sampling period – see Fig 4.5. The
reading for that stream is then held until that stream is again
sampled and updated. This includes 'Loss of Sample' and de-
selection of the stream.
The stream sequence would be normally set to sample each
stream in turn, i.e. on a three stream version this would be set
to 1, 2 ,3. However, greater priority could be given to a
particular stream (e.g. stream 1) by programming the
sequence 1, 2, 1, 3 or 1, 1, 1, 2, 3 etc.
Front panel stream LEDs provide status information on each
stream as follows:
Green .................... Stream selected.
Flashing green ...... Sample currently being sampled.
Red ........................ Sample lost on stream.
Not illuminated ...... Stream de-selected or not fitted.
Stream 1
Solenoid Valve Open
Dead Time 8 mins.
Sampling Interval
Nominal 12 mins.
12
Color Compensation Applied
Nominally eight fill/drain cycles
(approximately 10 minutes)
Reading Taken for
Stream 1
Stream 2
Solenoid Valve Open
Dead Time 8 mins.
Update Time
6 mins.
Fig. 4.5 Multi-Stream Timing
Further eight fill/drain cycles
for recovery on sample
SV4
De-energized
SV5
If the stream is unavailable throughout the sampling period the
monitor selects the next stream in the sequence. The red
stream lamp remains on until the stream is sampled again; if
the stream has been reinstated, the l.e.d. changes to green
and the display is updated as normal.
Single Stream Mode for Maintenance
To carry out any maintenance it is necessary to switch to a
single stream provided that a stream is available. If not, a
solution could be introduced via the SECONDARY CAL valve
(energized on Programming Page 2.2 – see Appendix A).
Single stream mode is initiated by selecting one stream on
Programming Page 3.3, Appendix A. This stops the multi-
stream sequencing and enables the display and the current
output to respond to changes on each drain/fill cycle. This
mode is used to check the basic performance of the monitor,
such as response or drift, without waiting for the normal stream
update.
Selecting more than one stream puts the monitor to multi-
stream operation.
Reading Taken for
Stream 2
Stream 3
Solenoid Valve Open
Finish of Sequence
Reading Taken for
Stream 3
Stream 4
Solenoid Valve Open
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