Exercise A
57
software) returns to 1400ml/min, or to the original flow rate if this was less. Lock the
knob by pushing it back in.
Effect of Inlet and Outlet Flow Rates
Investigate the effect of an inflow rate greater than the outflow rate, and of an outflow
rate greater than the inflow rate.
Create a new results sheet by selecting the appropriate icon in the tool bar of the
software.
Select the
icon to begin data logging.
Decrease the outflow rate by closing the drain valve in the base of the vessel, but do
not completely close the valve. This will decrease the outflow rate compared to the
inflow rate. Wait until the oscillations stabilise in magnitude and duration.
Increase the outflow rate compared to the inflow rate by fully opening the drain valve.
Continue data logging until the oscillations in fluid level reach stable values.
Select the
icon to finish data logging.
Effect of Vessel Volume
In the software, close the valve SOL1 as follows: Select the ‘Controller’ radio button.
Select ‘Control’ as at the start of the exercise, to open the PID controller window.
Check that ‘Manual’ Mode of Operation is selected then set ‘Manual Output’ to 0%
and click on ‘Apply’. There should be an audible click as the valve closes, and flow
into the large process vessel should stop.
Fully open the drain valve in the base of the large process vessel and allow the water
to drain from the vessel.
Carefully remove the lid on top of the large process vessel and remove the inner
cylinder. This increases the effective volume of the process vessel.
Replace the lid and partially close the drain valve.
Repeat the procedure described at the start of the exercise, remembering to create a
new results sheet before commencing data logging.
If there is sufficient laboratory time then the investigations of Set Point value, feed
rate and inlet/outlet flow rates may be repeated at this increased volume.
Results
For easy identification or results, it is suggested that each results sheet is renamed
with a descriptive title (e.g. ‘Flowrate’, ‘Volume’, etc.). The entire workbook should be
saved with a suitable filename for future reference (e.g. PCT40 Exercise A).
Each set of data should be plotted on a graph of fluid level against time.
Make a comparison of each variation in the experimental conditions against the
graph of the initial set of results, noting the difference in response.
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