Hanna Instruments HI 9829 User Manual

Page 49

7.7 TURBIDITY CALIBRATION
From the “Calibration” menu select “Single
param. calibration” and then “Turbidity
calibration”. The display shows two options:
“Calibrate turbidity” and “Restore factory calib”.

The Hanna turbidity sensor conforms to ISO
7027 standards which specifies the angle
between the emitted and detected light and the light source wavelength. For
best results perform a three point calibration at 0.0, 20.0, and 200.0 FNU.
Although the basis of calibration for this measurement is the standard Formazin,
from a practical point of view, these standards require daily preparation. A
secondary standard based upon polystyrene beads is a more practical approach.
See APPENDIX D – Accessories for information regarding Hanna calibration
solutions.
Note:

Note:

Note: Turbidity standard formulations made with polystyrene beads are

instrument specific and cannot be swapped with standards made for
another turbidity sensor model.

Verify the sensor is clean before calibrating. The use of the HI 7698293 calibration
beaker is required for this procedure.

Warning:

arning:

arning: Do not calibrate in bring sunlight.

Calibration is required every time the sensor is replaced and is recommended to
be part of yearly validation of your system.

7.7.1 Preparation
Pour quantities of selected standard solutions into clean beakers for rinse. Fill
the HI 7698293 calibration beaker with the zero standard. Submerse the turbidity
sensor into zero rinse beaker and then shake off excess solution. Place the sensor
into the calibration beaker. It is extremely important that no bubbles are present
on the optical area. Gentle agitation of sensor or beaker may be required to
dislodge bubbles before screwing the beaker on
fully. Do not place hands on the calibration beaker
during calibration.

7.7.2 Standard Procedure
Select “Calibrate turbidity” from the menu.
The measured value is shown on the main part of the display, while the standard
value appears on the secondary level.