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4
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Operating Procedures
1. With the COVER PLATE (1) open, carefully clean
the PRISM (3) and REFLECTING WINDOW (2)
with a soft cloth. Avoid scratching the surfaces.
2. Aim the refractometer toward a light source and
select the 0-50% scale by rotating the SCALE SE-
LECTOR (6).
3. Rotate the EYEPIECE (7) to obtain the clearest
focus.
4. Adjustment of the null (reference point):
A. Open the COVER PLATE (1).
B. Apply a few drops of pure distilled water onto
the REFRACTING PRISM (3).
C. Close the COVER PLATE (1).
D. Turn the CALIBRATION SCREW (4) so that
the dark and light boundary line coincides ex-
actly with the 0% line reading on the scale in
the 0-50% range.
5. Carefully dry the prism platform and the LIGHT
REFLECTING WINDOW (2) with a soft cloth.
6. To test your sugar sample, rotate the SCALE
SELECTOR (6) to select the 0-50% range or the
50-80% range.
7. Place a few drops of the test solution on the prism
and close the COVER PLATE (1) so the solution
spreads evenly on the prism.
8. Aim the light reflecting windows toward the light
source and focus the eyepiece on the boundary
line of the light and dark hemispheres.
9. The boundary line indicates the concentration of
sugar in the test sample.
10. If the boundary line is too low or too high to be
read on the scale you selected, rotate the SCALE
SELECTOR (6) to the other scale.
0-50%
scale
-50
-45
-40
-35
-30
-25
-15
-10
-5
-0
85—
80—
75—
70—
65—
60—
55—
50—
50-80%
scale
