HF scientific MicroTOL Online Turbidimeter - Manual (Page 17)

MICRO TOL (5/10) 11
Rev. 4.8
5.0 Instrument Calibration
The instrument was calibrated and tested prior to leaving the factory. Therefore, it is
possible to use the instrument directly out of the box. Under normal conditions, re-
calibration is recommended at least once every three months
1 .
Relay contacts will change to the alarm state while the instrument is in the calibration
and/or in the configuration mode. While in the calibration mode, the instrument has a
time-out feature that automatically returns the system operation to the AUTO mode after a
fifteen (15) minute period of inactivity.
5.1 Calibration Standards
If the Micro TOL will be used over the entire range of .02 to 1000 NTU a complete
calibration as described below will be required. If instrument accuracy is only required
below 10 NTU, such as potable water, a calibration may be performed using only a 10
NTU and a 0.02 NTU standard. To calibrate starting at the 10 NTU, press the
ubutton to
bypass the 1000 NTU and proceed to Section 5.2 Calibration Procedures, step 5.
We recommend that the following materials be used during calibration to achieve the full-
scale accuracy stated in this manual:
1. 0.02 NTU
ProCal
Calibration Standard available from HF scientific
2. 10.0 NTU ProCal Calibration Standard available from HF scientific
3. 1000 NTU ProCal Calibration Standard available from HF scientific
It is well known that diluted Formazin is unstable. If Formazin is used to calibrate the
instrument, ensure that a fresh stock suspension of Formazin is used to achieve the
accuracy quoted for the instrument. A Formazin Stock Solution Kit is available from HF
scientific (Catalog No. 50040). The HF scientific
ProCal , primary calibration standards
(refer to section 11.0 Accessories and Replacement Parts List) are more stable than
Formazin and have a minimum shelf life of 12 months. Prior to recalibration, review the
expiration dates, to ensure that the standards have not expired.
Note: The range of Models 20055 & 20056 is .02 to 100 NTU. For calibrating these models
replace the 1000 NTU standard with a 100 NTU standard.
1
The EPA recommends that on-line turbidimeters be calibrated with a primary standard at least once every three
months if they are to be used for EPA reporting.