YSI VisoTurb 700 IQ - Manual (Page 28)

Measuring VisoTurb
®
700 IQ (SW)
4 - 2 ba76039e01 01/2012
4.2 Calibration
4.2.1 General information
Why calibrate? The following factors can change with time and affect the measurement
results:
 the optical characteristics, e.g. color and particle size, and the
density of the measuring medium (e.g. dependent on the season)
 the conditions at the measuring location (e.g. due to growing
deposits on the ground and walls)
The effect of the measurement environment can be reduced by
ensuring the optimum conditions (see section 3.2.1) and can be
compensated by an application offset (see section 4.2.2).
For measurements of the total suspended solids, a user calibration is
always required (see section 4.2.3).
When to calibrate? A new user calibration is required if there is any change of the
characteristics of the measuring medium or any change of the
environment at the measuring location.
Note
Values of the user calibration that have been entered are saved in the
controller and thus assigned to the measuring location (not to the
sensor). Therefore, if the sensor is exchanged, no new user calibration
is required.
How is a calibration
carried out?
The actual level of total suspended solids of your measuring medium is
determined by a reference measurement (e.g. gravimetric according to
DIN 38414).
If the reference measurements do not deviate from the optically
determined measured value of the VisoTurb
®
700 IQ (SW), the sensor
is already optimally adapted to the measuring situation.
If the reference measurements do deviate from the optically
determined measured value of the VisoTurb
®
700 IQ (SW), proceed
as follows:
 Optimize the conditions at the measuring location (see section
3.2.1)
 Perform a user calibration (see section 4.2.3)
if you measure the total suspended solids.
 Perform an application offset (see section 4.2.2),
if the measuring environment affects the measured values