Armfield Instruction Manual
70
Select the
icon to begin data logging.
Allow the oscillations in fluid level to reach steady values of magnitude and duration.
Select the
icon to finish data logging.
Select the
icon to create a new results sheet.
Repeat the procedure, altering the set point and logging the change in fluid level until
the oscillations reach stable values. Suggested values for the pressure switch set
point value are 150, 250 and 300mm. Remember to create a new results sheet for
each set of data.
Feed Rate
Create a new results sheet by selecting the icon in the tool bar of the software.
Select the
icon to begin data logging.
To change the inlet feed rate, adjust the pressure regulator on the inlet pipe of the
apparatus: Pull the knob outwards from the body of the regulator. Turn the knob
anticlockwise until the flow rate reading is approximately 2/3 of the original value
(1000ml/min is suitable if an initial value of 1400ml/min was used). Lock the setting
by pushing the knob back in.
Allow the oscillations in fluid level to reach steady values of magnitude and duration.
Alter the feed rate again by repeating the adjustment to the pressure regulator. Allow
the fluid level oscillations to stabilise again.
Continue to reduce the feed rate until the fluid level in the vessel no longer returns to
the set point level (the drain rate exceeds the inlet flow rate).
Select the
icon to finish data logging.
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.
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.
Select the
icon to begin data logging. Continue logging until the oscillations about
the set point value reach stable values, then select the
icon to finish data
logging.
Create a new results sheet by selecting the
icon.
Increase the outflow rate compared to the inflow rate by fully opening the drain valve.
Log the fluid level as before, and stop logging when the oscillations once more reach
stable values of magnitude and duration.
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