MR100ATC - Salinity Refractometer
Specifications
Scale Range Resolution
Parts Per Thousand 0 to 100 0/00 1 0/00
Specific Gravity 1.000 to 1.070
Dimensions 7.6 x 1.5 x 1.5" (194 x 38 x 38mm)
Weight Approx. 8.0 oz. (227g)
Shadow-line Æ
Operation
The instrument measures the refractive index of the sample and displays the result in parts
per thousand ( 0/00 ) and specific gravity.
1. Zero Adjustment
Put distilled water on the prism; enough to cover the entire prism. Close the cover plate and rotate
the adjusting screw so that the light/dark boundary line (known as the shadow-line) evens up with
the zero line. After the zero adjustment, clean the prism with soft cloth.
2. Sample Preparation and Reading
To take a reading, place a few drops of a sample liquid on the measurement prism. Ensure that
enough solution is added to the prism in order to cover the entire prism. Close the prism so that
the liquid spreads across the entire surface of the prism without air bubbles or dry spots (see
diagrams below). Allow the sample to remain on the prism for approximately 30 seconds. While
holding the instrument under a light source, look through the eyepiece. The salinity concentration
is determined by the intersection of the boundary of the light and dark fields (known as the
shadow-line) on the printed scale. The left side of the scale indicates the specific gravity and the
right side parts per thousand. If the scale appears out of focus, the eyepiece may be adjusted by
rotating the knurled portion. The instrument also features an eye guard to prevent stray light from
entering the eyepiece and causing reflections. It may be necessary to adjust the position of the
light source to maximize the contrast of the shadow-line. Under normal conditions, optimal
contrast is obtained by holding the instrument underneath and perpendicular to a light source.
(florescent light is not recommended) - Once a reading has been taken, wipe dry with a clean
cloth (do not wash or rinse) and place the instrument in the supplied plastic case. Store the
instrument in a safe, dry environment.
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