LW Scientific Refractometer - Manual (Page 2)

P. 770.270.1394 F. 770.270.2389 865 Marathon Parkway Lawrenceville GA 30046
MKT-7.5.3-L-036 | Rev 1
Operation
Maintenance and Cautions
(Protein / Specific Gravity Model CTL-REFM-PRSG): Lift the cover plate and add 1 or 2 drops of urine or serum (or
plasma) depending on which test is desired. Lower the cover plate. Lightly press the cover plate, making sure the
liquid is evenly distributed across the prism. You can now read the value of the protein concentration (for serum or
plasma) or specific gravity (for urine) from the appropriate scale by reading the boundary line between the light and
dark area as it intersects the scale.
(BRIX Model CTL-REFM-BR32): Lift the cover plate and add 1 or 2 drops of liquid, such as wine, fruit juice, or other
liquids containing sugar. Lower the cover plate. Lightly press the cover plate, making sure the liquid is evenly distrib-
uted across the prism. You can now read the percentage of sugar content from the percentage scale by reading
the boundary line between the light and dark area as it intersects the scale.
•Testing quality of Colostrum for feeding young calves (BRIX Model CTL-REFM-BR32):
Follow the operating instructions above for the BRIX refractometer, using 1 or 2 drops of colostrum. Research
indicates that BRIX scores of 22% or higher represent good quality in colostrum, 18-21% represent colostrum that can
be used for second feedings, and scores below 17% will need to be supplemented.
•Testing total solids in milk for feeding older calves (BRIX Model CTL-REFM-BR32):
Follow the operating instructions above for the BRIX refractometer, using 1 or 2 drops of milk. The expected content
of total solids in normal milk would be 12.5% to 13%. The following equation was developed by Penn State to
convert BRIX reading to total solids in milk:
TOTAL SOLIDS = (0.9984 x BRIX reading) + 2.077
Therefore, a BRIX reading of 10.4% equals 12.5% total solids, and a reading of 10.9% equals 13% total solids.
After use, clean with distilled water only. Rinse and dry the glass and metal parts. Store the Refractometer in its
case in a clean, cool, dry, non-corrosive atmosphere.
Handle the hinged cover plate carefully, so as not to break the hinge.
When calibrating, the distilled water and specimens to be measured should all be the same temperature. If the
temperature varies greatly between the two, the calibration should be adjusted once every 30 minutes.
Never immerse the Refractometer in water.
Use extra caution when cleaning to avoid scratching the prism.
When used properly, the LW Scientific Refractometer will give years of reliable performance.
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As with any precision instrument, care should always be used when handling, cleaning, and storing. Storage in a
clean, dry, non-corrosive atmosphere is recommended. Avoid dropping or strong shocks.
Protein / Specific Gravity Scale BRIX scale