Refractometer
Components
Calibration Ring
Mechanism used to zero or calibrate the refractometer,
without the requirement of additional tools.
Rubber Hood
Houses and protects the focusable lens. Prevents
light from entering through the eyepiece during use.
Rubber Grip
Insulates the refractometer
against hand heat for accurate
results.
Non-Roll Stand
Protects against damage to the
instrument when set down between
measurements.
Daylight Plate & Prism
The prism and sample are covered by
the daylight plate during readings.
This refractometer is an optical instrument -- it can become damaged if dropped or handled in a rough manner.
The prism is made of optical glass and is susceptible to scratches -- do not apply any rough or abrasive
material and take care when cleaning the prism.
After each use, clean the prism surface and daylight plate with a soft cloth or tissue soaked in water and
wipe off with a dry cloth or tissue.
Do not hold the refractometer under a stream of water from a faucet. Do not splash it with or dip it in water.
If the surface of the prism becomes coated with an oily solution or similar, it will repel test samples and
affect readings. If this occurs, the prism should be cleaned with a weakened detergent or similar solvent.
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Calibration
Precautions
Calibration should be conducted at the start of each day or when any
shifts in ambient temperature occur. If recalibration is impractical, refer
to the directions and temperature correction table on the following page.
For standard calibration procedures, please follow the directions below.
Open the daylight plate and apply one or two drops of distilled water on to
the surface of the prism. Hold the prism at an angle close to parallel with
the floor so the distilled water will not run off of the prism.
Gently close the daylight plate over the prism. The distilled water should
spread as a thin, even layer in between the daylight plate and the prism.
By looking through the daylight plate, ensure that the distilled water covers
the ENTIRE surface of the prism. If there are bubbles and gaps or if the
distilled water is only on one portion of the prism, the distilled water must
be reapplied (Figure 1). Inaccurate calibrations will result if the prism is
not covered correctly.
Looking through the eyepiece, hold the refractometer and direct the daylight
plate upwards towards light. If the scale is not in focus, adjust it by gently
turning the eyepiece (rubber hood) either clockwise or counterclockwise.
Be careful not to overturn the focusing mechanism.
When the refractometer scale is viewed through the eyepiece, the upper
field of view will be seen as blue and the lower field will be seen as white
(Figure 2). Confirm that the boundary line crosses the scale at “0” (Figure 3).
If the boundary line falls above or below zero, gently loosen the screw on the
calibration ring. While looking through the eyepiece, gently turn the calibration
ring clockwise or counterclockwise until the boundary line is at zero. Once
this is achieved gently tighten down the set screw. (NOTE: Do not over-tight-
en. If the set screw is over-tightened, the boundary line may shift slightly).
When calibration is complete, gently wipe the prism using tissue paper.
Thank you for purchasing this VEE GEE Refractometer. With the user in mind, VEE GEE Refractometers are built
from modern designs and, with proper care, this instrument should provide many years of reliable performance.
It’s recommended this manual is read entirely before using the refractometer for the first time.
Introduction
Figure 1
Figure 2
Figure 3
Figure 4
Figure 3
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General
Use
Open the daylight plate and apply one or two drops of the sample solution
to the surface of the prism. Hold the prism at an angle close to parallel
with the floor so the sample will not run off of the prism.
Gently close the daylight plate over the prism. The sample solution should
spread as a thin, even layer in between the daylight plate and the prism.
By looking through the daylight plate, ensure that the sample solution
covers the ENTIRE surface of the prism. If there are bubbles and gaps or if
the sample is only on one portion of the prism, the sample solution must
be reapplied (Figure 1). Inaccurate readings will result if the prism is not
covered correctly.
Looking through the eyepiece, hold the refractometer and direct the daylight
plate upwards towards light. If the scale is not in focus, adjust it by gently
turning the eyepiece (rubber hood) either clockwise or counterclockwise.
Be careful not to overturn the focusing mechanism.
When the refractometer scale is viewed through the eyepiece, the upper
field of view will be seen as blue and the lower field will be seen as white
(Figure 4). The reading is taken at the point where the boundary line of the
blue and white fields crosses the scale (Figure 5). The value is the Brix%
reading of the sample.
When each measurement is complete, the sample must be cleaned from
the prism using tissue paper and water.
Calibration Ring Set Screw
Secures the calibration ring in place to
protect from any shifts which could occur
during use.
Figure 5
Figure 3
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