Optika Italy HR-110 Manual De Instrucciones página 9

USING THE REFRACTOMETER HR-150
Step 1. Placing the liquid on the prism
Open daylight plate, clean the refraction prism with a soft and clean flannelette, and place 2 - 3 drops
of distilled water or calibration liquid on the main prism. Close the daylight plate so the water spreads
across the entire surface of the prism without air bubbles or dry spots. Leave the sample on the pri-
sm for approximately 30 seconds to allow it to adjust to the same temperature as the refractometer
before going to the next step.
Step 2. Looking at and focussing the scale
Hold the daylight plate in the direction of a light source and look into the eyepiece. You see a circular
field with vertical scale graduations along the centre of the visual field (you may have to focus the
eyepiece to clearly see the graduations). The upper portion of the field should be blue, while the
lower portion should be white.
Step 3. Setting the scale to zero
Using distilled water or calibration liquid as a sample, look into the eyepiece and turn the calibra-
tion screw, at the side of the refractive prism stand, until the boundary between the upper blue field
and the lower white field meet exactly on the zero in the scale. Turn the adjustment tube to change
between the scales 0-50% and 50-80%. That is the end of the calibration.
Make sure the room temperature is suitable for the solution you are using. When the temperature
of the environment (not the sample) changes by more than 5 °F, we recommend recalibrating the
instrument to maintain accuracy and reproducibility.
Step 4. Testing your sample
Remove the calibration liquid from the prism and repeat step 1 substituting the water or calibration
liquid with your sample to analyse. Then continue with step 2. After having finished this step, change
to the correct scale, and the Brix concentration can be read directly where the boundary line of blue
and white areas crosses the graduated scale.
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