Calibration
of Refractometer
Ø
Ensure that the
instrument and area is properly clean and free from dust.
Ø
Place instrument
such that proper light can be reflected through the mirror.
Ø Unlock the prism and clean its surface using distilled
water or naphthalene bromide with the help of tissue paper.
Ø
Place few drops
of Distilled Water/Toluene/Carbon Tetrachloride
and allow it to smear on the prism surface.
Ø
Quickly close the
prism lock.
Ø
Adjust the light
using shield fixed below the prism.
Ø
Adjust the eye
piece cross wire with a knob by rotating it in a clockwise or anti-clockwise
direction so that the sharp demarcation line passes through its center.
Ø Observe sharp demarcation produced in circle form
having dark and light portions equally.
Ø
Use a knob
present just above the prism for fine adjustment.
Ø
Repeat the
procedure three times.
Ø
Observe and
record the readings using magnifying lens of the instrument from the scale
Following
Solvents Should be used for calibration of Refractometer
|
S.No |
Solvent |
Observed refractive index |
Acceptance criteria |
Temperature |
|
01 |
Distilled water |
|
1.3320 —1.3330 |
20 ± 0.5 ◦C |
|
02 |
Toluene |
|
1.4964 --- 1.4974 |
20 ± 0.5 ◦C |
|
03 |
Carbon Tetrachloride |
|
1.4598----1.4608 |
20 ± 0.5 ◦C |
If the
readings falls within the acceptance instrument should be tagged as “Calibrated”. In case of any failure
inform the concerned performed.
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