Variable Conditions In Taking Readings; Calibrating With Distilled Water; Operating Instructions - Reichert Abbe Mark II Manual De Instrucciones

The mode selector switch is used to select measurement modes:
The modes are:
• % Solids-TC - Temperature Compensated % Solids as Sucrose
(°Brix) per International Commission for Uniform Methods of Sugar
Analysis Refractive Index Tables.
• n - Refractive Index
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• % Solids - Non-Temperature Compensated % Solids as Sucrose
The reticle adjustment access hole permits vertical adjustment
of the crosshair during calibration procedures.
Depress the read display button to obtain measurement values.
Depressing the temperature display button will provide a reading
of the prism temperature.
Readings are shown digitally in the display window.

5.1 Variable Conditions in Taking Readings

Distilled water readings above 20°C can be obtained in the
refractive index % Solids-TC mode, assuming the instrument is
properly calibrated. Correct readings cannot be obtained in the
non-temperature compensated % Solids mode when the water
sample temperature is above or below 20°C. Refractive index
(n ) readings for distilled water can be obtained from O °C to
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80°C (see Chart 1 for values between 18-30°C).
Refractive index is inversely proportional to temperature. As
temperature increases, the solution density decreases and the
refractive index or % Solids reading will decrease. As temperature
decreases the solution density will increase and the refractive
index (% Solids) will increase. The % Solids-TC mode
automatically corrects the reading for temperature based on the
temperature coefficient of sucrose in solution. This coefficient is
typical of most aqueous solutions.

5.2 Calibrating With Distilled Water

To calibrate:
1. Place a distilled water sample on the measuring prism surface
and let it stand undisturbed for 3-5 minutes to obtain temperature
stability. Turn the mode selector switch to the refractive index
(n ) position.
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2.Focus the eyepiece until the crosshair clearly appears.
3. Rotate the adjustment control clockwise until the shadow line
nearly meets the crosshair. Use the dispersion correction wheel
to obtain the sharpest possible color-free shadow line. Adjust the
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English
shadow line to meet the crosshair. Press the Read button and
record the n value, then press the temperature button and record
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the temperature.
4. If the instrument is properly calibrated, the reading will be 1.3330
less 0.0001 for each degree above 20°C or plus 0.0001 for each
degree below 20°C.
If the instrument is not calibrated, determine the proper reading
(Chart 1) and rotate the adjustment control and depress the READ
display button until the display reads correctly. (The shadow line
will no longer intersect the crosshair on the reticle.)
5. Insert a 1/16" Allen wrench into the reticle adjustment access
hole (Figure 2) located in the dispersion correction wheel. Turn the
wrench to bring the crosshair into proper position on the shadow line.
NOTE: The final movement made with the adjustment correction
control wheel should always be in a clockwise direction. The
shadow line will move upward.
6. Turn the mode selector to the BX-TC position. Press the READ
button. An LED reading of 000.0 or 0.1 is normal. If a negative
sign and a decimal point appear, no reading can be given.
Go on to the next step.
If a " No Reading" condition persists after repeated READ attempts,
rotate the adjustment control until the display reads 000.0 or 0.1.
Only a very slight adjustment will be necessary. Readjust the
reticle crosshair to the shadow line.
The display should now read 000.0.
Repeat the steps until the display reads 000.0.

6.0 OPERATING INSTRUCTIONS

To begin operation:
1. Open the prism assembly cover (Figure 4) and remove the
protective lens tissue. Clean the measuring prism surface with alcohol
and then distilled water. Wipe with a clean soft cloth or lens tissue,
but do not wipe the measuring prism surface while it is dry. Any
residue left on the prism can affect the accuracy of readings.
2. Turn the mode selector to the desired mode position.
3. Apply a sample solution to the measuring prism surface using a
glass dropper. Close the prism cover and position the illumination
arm so that the exposed face of the upper prism is fully illuminated.