Exercise K
99
Partially close the drain valve at the base of the large process vessel to produce a
constant low outflow to drain.
Select ‘Configure’ from the Sample menu, and set sampling to Automatic at intervals
of 10 seconds, with duration as Continuous.
In the software, set a value of 20% for peristaltic pump speed. The pump should start
working. If the pump does not start immediately, increase the speed value to 50%.
Once the pump is working, carefully close the top of the pump, ensuring that the
silicone tubing passes through the entry and exit holes and is not trapped by the lid.
Fluid should now be drawn down out of the process vessel through the pump to
drain.
Select the
icon to begin data logging.
Allow the fluid level in the process vessel to approach a value of 200mm. By altering
the speed of the pump A in the software, control the outflow rate in order to maintain
the fluid level at 200mm.
Select the
icon to finish data logging.
Create a new results sheet by selecting the
icon.
Disturbances
Within the software it is possible to introduce disturbances in the outflow from the
vessel by opening the Normally Closed solenoid valve SOL 3:
Select the
icon to begin data logging.
In the software, select the switch to open valve SOL 3. Change the speed of pump A
by using the arrow keys, and alter the outflow rate in order to maintain a fluid level of
200mm. Note the change in control action required to maintain fluid level with valve
SOL 3 open.
Close valve SOL 3 and continue to maintain the fluid level.
Select the
icon to finish data logging.
Create a new results sheet by selecting the
icon.
Feed Rate
Select the icon to begin data logging.
To change the inlet feed rate, change the setting of the Proportioning Solenoid Valve
as shown in the software. A step change may be produced by typing the new setting
directly into the display box. A change of 20% up or down is suggested.
Use the speed of pump A to control outflow rate maintain fluid level. Note the change
in control action required due to the inlet flow rate change, and whether the change in
flow rate was an increase or a decrease.
Change the PSV valve setting to 100% (fully open). Note whether the fluid level can
be maintained using pump A alone at this maximum inlet flow rate.
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