User's Manual

Chapter 4 - Calibration - 49
Turbine calibration
The system uses a turbine flowmeter. It opposes a very low resistance to flow. The air
passing through the helical conveyors, takes a spiral motion which causes the rotation of
the turbine rotor. The rolling blade interrupts the infrared light beamed by the three
diodes of the optoelectronic reader. Every interruption represents 1/6 turn of the rotor,
this allows to measure the number of turn in the time. There is a constant ratio between
air passing through the turbine and number of turns. This allows an accurate measure of
flows and volume. The turbine flowmeter doesn't need daily calibrations as it is not
affected by pressure, humidity and temperature.
To work properly, the turbine only requires the rotor to rotate freely without any friction
that might be caused by dust that can be easily avoided with an ordinary cleaning
procedure (see Maintenance).
However in order to ensure accuracy it's recommended to run periodically the
calibration procedure. Calibration has to be carried out with a calibration syringe of 3
litres volume, the calibration procedure is totally managed by software.
A measurement system should be calibrated daily in order to ensure maximum accuracy
and reliable test results. If a correct maintenance is provided it’s possible to check the
calibration of the turbine flowmeter even at relatively long intervals (i.e. 1 month). The
calibration procedure assures valid and verifiable results within a ±3% accuracy.
Assembling the flowmeter for calibration
1. Connect the Opto-reader to the calibration syringe through the adapter.
2. Connect the flowmeter to the syringe with the rubber cylinder supplied in the
standard packaging.
Note: If a bacterial filter is used for the tests, do use it also during the turbine
calibration.
Calibrating the turbine
Turbine calibration using the PC software
After having run the calibration program:
1. Select Reference Values from the File menu. If your syringe has a different value
from the default one (3 litres), please enter the correct value.
2. Select Calibration/Turbine….
3. When the Calibration Turbine dialog box appears with the syringe piston initially
pushed all the way in, move the piston in and out for 5 inspiratory strokes and 5
sss
Note
: If you are using a slow
PC, we recommend to set
an higher refresh time.