Control characteristic for direct and inverted control action
Field R236 offers two control characteristics
for selection which have the effects shown in
the following diagram.
5.5.3
USP 23 function (conductive only)
The Liquisys M can measure and monitor
the uncompensated conductivity (R2 (6))
according to USP (“United States
Pharmacopeia”) guidelines.
USP requirements on measurement
The measurement is performed as follows:
• Measurement of uncompensated
conductivity
• Temperature measurement at place of
conductivity measurement
• Rounding of temperature to the next
5 °C step
• Determination of applicable monitoring
value from a table (see below)
• Alarm signalling in the event the monitoring
value is exceeded.
The measurement is performed without
compensation, and the measured value is
compared to a monitoring value (see table)
for pure water.
An alarm is issued when the monitoring value
is exceeded.
An adjustable pre-alarm can be used to alert
to undesirable operating conditions in time.
X
X
w
w
100 %
100 %
K
p
p
K
Y
Y
1
1
Direct
Inverted
REGEL03.CDR
Fig. 5.9
Control characteristic of a
proportional controller
with direct and inverted
control action
Temperature [°C]
Conductivity [µS/cm]
Temperature [°C]
Conductivity [µS/cm]
0
0.6
55
2.1
5
0.8
60
2.2
10
0.9
65
2.4
15
1.0
70
2.5
20
1.1
75
2.7
25
1.3
80
2.7
30
1.4
85
2.7
35
1.5
90
2.7
40
1.7
95
2.9
45
1.8
100
3.1
50
1.9
Instrument configuration
Liquisys M CLM 223 / 253
34
Hauser
