Switching fluids
While fluid remains stagnant within the Heated Pencil, its temperature
will climb higher than the setpoint. When you switch liquids, there will
be a small temperature overshoot like the one shown in Figure 8 below.
When all solution flow is stopped, the ThermoClamp tries to maintain the
desired bath temperature by increasing heat to the Pencil. Without liquid
flow, none of this added heat reaches the chamber, so the Pencil continues
heating until the overtemp LED lights or the ThermoClamp detects the
thermal runaway and stops overheating.
35.4
35.6
35.8
36
36.2
36.4
36.6
36.8
-20
-10
0
10
20
30
40
50
Insulation, Bath 5cc/min
Insulation, no bath
Setpoint 37C
Drug 5cc/min
7/3/2003
Overshoot
Figure 9.
Temperature vs. Time curves for fluid switching
35.4
35.6
35.8
36
36.2
36.4
36.6
36.8
-20
-10
0
10
20
30
40
50
Insulation, Bath 5cc/min
Insulation, no bath
Setpoint 37C
Drug 5cc/min
7/3/2003
29
