Hach-Lange 2100P iso - Portable Turbidimeter Instrument - Manual (Page 19)

Section 2, continued
Page 19
4650098 operation.fm Calibration
during measurement, the initial value is displayed in 12 seconds and is updated
every 1.2 seconds as long as the READ key is held.
When the instrument is turned on, the instrument defaults to the signal averaging
mode which was used during the last measurement.
2.3 Calibration
Calibration of the 2100P ISO Turbidimeter is based on formazin, the primary
standard for turbidity. The electronic and optical design provide long-term stability
and minimize the need for frequent calibration. The two-detector ratioing system
compensates for most fluctuations in lamp output. A formazin recalibration should
be performed at least once every three months, more often if experience dictates.
When calibration is necessary, use a primary standard such as StablCal™ Stabilized
Standards or formazin standards.
For Hach turbidimeters, use only StablCal® Stabilized Formazin or formazin
standards. Hach Company cannot guarantee the performance of the turbidimeter if
calibrated with co-polymer styrene divinylbenzene beads or other suspensions.
2.3.1 StablCal Stabilized Formazin Standards
2.3.1.1 Storing and Handling StablCal Stabilized Standards
For optimum results when using StablCal Stabilized Standards, adhere to the
following recommendations:
• Do not transfer the standard to another container for storage.
• Do not return standard from the sample cell back into the its original container.
Standard contamination will result.
• Store standards between 0 and 25 °C.
• For long-term storage, refrigeration at 5 °C is recommended. Do not store above
25 °C.
• Allow the standard to acclimate to ambient instrument conditions before use (not
to exceed 40 °C).