Armfield Instruction Manual
184
Note how easy it is to maintain a constant pressure using manual control, and how
quickly the system responds to control actions.
Select the
icon to finish data logging.
Create a new results sheet by selecting the
icon in the tool bar of the software.
Disturbances
Within the software, it is possible to introduce a disturbance to the system by
changing the speed of the gear pump that is connected in series with the PSV and
the manifold block orifice:
Select the
icon to begin data logging.
In the software, set the speed of the gear pump to 70%.
Note how rapidly the pressure changes as a result of this new setting, and the control
actions required to return the pressure to its previous value.
Set the speed of the gear pump to 30%, and once more note the speed of response
and the action required to return the pressure to the Set Point.
Set the gear pump to 50%. Repeat the previous observations.
Select the
icon to finish data logging.
Create a new results sheet by selecting the
icon in the tool bar of the software.
Note that the differential pressure sensor is not designed for use at inlet flow rates of
greater than 1500ml/min. The combined settings for the PSV and the gear pump
should therefore be kept low enough that the flow rate remains below this value.
Results
For easy identification or results, it is suggested that each results sheet is renamed
with a descriptive title (e.g. ‘Disturbances’, etc.). The entire workbook should be
saved with a suitable filename for future reference (e.g. PCT40 Exercise DD).
Each set of data should be plotted on a graph of pressure P3 against time.
Write up your experiment, discussing the speed of response when controlling line
pressure directly, and the ease of manual control for this variable. Comment on the
sensitivity of the process to disturbances.
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