CALFLU202-3 is a special calibration fluid intended for calibrating the span (high-end) point on MISCO Palm Abbe digital refractometers. Although it is important to Zero-Set the Palm Abbe refractometer to water daily, you may at some point want to set the span adjustment as well.
The refractometer span should be set if you notice a general degradation in the instrument’s accuracy and precision and/or on a periodic basis determined by your particular history with the instrument. It is recommended to set it once a year to maintain maximum measurement precision.
Factors affecting your decision to set the span adjustment include how often the instrument is used, how roughly it is handled, how often it is exposed to large temperature changes, and the level of precision you require for your measurements. When setting the span adjustment, it is important to keep the instrument and calibration fluid as close to 20 ‘C (68 ‘F) as possible; it should never be more than a couple of degrees away from this temperature.