K-Patents PR-23 - Manual (Page 49)

6 Configuration and calibration 41
Wash-related hold (Section 6.2.2) and external hold (Section 6.2.1) are connected in
parallel. If at least one of them is active, the measurement result will be in hold. Tol-
erance time (Section 6.2.3) is independent of these two, but the tolerance time will be
reset whenever there is another reason for the measurement hold.
For example, if the tolerance time is set to 10 seconds, and wash hold becomes active
after 7 seconds, the remaining tolerance time will be reset to 10 seconds After the
wash is over, there is still 10 seconds of tolerace time remaining.
6.2.6 Hold and signal damping
The signal filtering (damping) is stopped during hold. The last filtered value is shown
on the screen and set to the mA output (if the concentration output is configured).
Figure 6.5 illustrates this behaviour (gray areas represent the periods when the hold
is active).
0 50 100 150 200
Time [s]
40
42
44
46
48
50
52
54
56
58
60
CONC [%]
Original signal
Filtered (damped) output
Figure 6.5 Damping stops during hold
6.2.7 Hold functions with DD-23
The K-Patents Digital Divert Control System DD-23 uses the displayed concentration
value in its decision logic. Due to this, the external hold functionality must not be
used with a DD-23, as it could potentially render the system unsafe by freezing the
measurement result.
The "hold during wash" must be used with DD-23. Otherwise the signal damping com-
bined with low nD values caused by the wash process may give erroneous information
to the DD-23 after the wash is over.