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Figure 7 Bath temperature fluctuation at various proportional band settings.
timum proportional band width are heater power setting and fluid viscosity.
The proportional band should be wider when the higher power setting is used
so that the change in output power per change in temperature remains the same.
The proportional band should also be wider when the fluid viscosity is higher
because of the increased response time.
The proportional band width is easily adjusted from the bath front panel. The
width may be set to discrete values in degrees C or F depending on the selected
units. The optimum proportional band width setting may be determined by
monitoring the stability with a high resolution thermometer or with the control-
ler percent output power display. Narrow the proportional band width to the
point at which the bath temperature begins to oscillate and then increase the
Table 3 Proportional Band — Fluid Table.
Fluid
Temperature
Water
Water
Eth-Gly 50%
Eth-Gly 50%
Eth-Gly 50%
Oil
Oil
Oil
Heater Setting
30.0°C
Low
60.0°C
Low
35.0°C
Low
60.0°C
Low
100.0°C
High
35.0°C
Low
60.0°C
Low
100°C
Low
Controller Operation
Proportional
Band
Stability
±0.0004°C
0.04°C
±0.001°C
0.04°C
±0.0005°C
0.05°C
±0.001°C
0.05°C
±0.007°C
0.4°C
±0.003°C
0.1°C
±0.002°C
0.2°C
±0.003°C
0.2°C
35
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