Sper Scientific 300003 Refractometer - Sugar Brix 0-80% - Manual (Page 5)

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11. After use, clean the refracting and illuminating
prisms with a soft cloth to remove any surface
residue.
12. The temperature of the null reference liquid should
be at the same temperature as the sample solu-
tion. For variations in temperature during use, the
null point should be recalibrated once every 30
minutes.
Temperature Correction
Your refractometer is designed to operate with distilled
water and sample solutions at a standard temperature
of 20°C (68°F). To compensate for temperature con-
ditions other than 20°C, use the Temperature Correc-
tion Table on Page 6.
Add to the reading when the temperature is above
20°C. Example: Actual temperature is 30°C. The
boundary line reads a concentration of 15%. Refer to
the Temperature Correction Table and locate the 15%
concentration column. Follow this column down to the
row that corresponds to the temperature of 30°C. At
the 0.78 correction point, the actual concentration per-
cent is 15% + 0.78%, or 15.78%.
Subtract from the reading when the temperature is be-
low 20°C Example: Actual temperature is 16°C. The
boundary line reads a concentration of 40%. Refer to
the Temperature Correction Table and locate the 40%
concentration column. Follow this column down to the
row that corresponds to the temperature of 16°C. At
the 0.30 correction point, the actual concentration per-
cent is 40% - 0.30%, or 39.70%.
If the null liquid (distilled water) is the same tempera-
ture as the test sample and the null line of distilled wa-
ter reads 0%, it is not necessary to refer to the correc-
tion table.