Robinair 75240 Hand Refractometer - Manual (Page 2)

Operating Instructions
Use the following instructions to operate the 75240
Hand Refractometer.
IMPORTANT: Read and understand all Operating
Instructions and Helpful Hints before operating
the Refractometer.
1. Aim the front end (prism [1] and cover plate [2] end)
of the refractometer toward a bright light; then adjust
the focusing ring of the diopter (5) until the reticle
(scale within the mirror tube) can be seen clearly.
2. To set the Hand Refractometer to a null or zero
point -
(a) Open the cover plate.
(b) Place one or two drops of pure distilled water
on the surface of the prism.
(c) Close the cover plate and press it lightly.
(d) Through the eyepiece, observe where the
shadow line falls.
(e) If necessary, adjust the correction screw (3)
with the screw driver provided to make the
shadow line coincide with the water line.
The Hand Refractometer should now have a null point,
and you are ready to begin measuring.
3. Open the cover plate, and wipe the water off the
surfaces of the prism and cover plate with the soft
cloth that is provided.
4. Then place one or two drops of the liquid needed to
be measured on the prism surface.
WARNING: To prevent personal injury, use
glass rod provided when measuring battery
liquid.
Close the cover plate and press it lightly. The reticle
reading on the shadowline is the freeze point of the
liquid, or an indication of the operation state of the
battery liquid.
5. After measurements are taken, wipe the liquid
completely from the prism surface with the soft cloth
and let dry.
CAUTION: To prevent damage to the
refractometer, do NOT use water to wash the
instrument.
6. Replace the refractometer in its case, and store it in a
dry, clean area.
Helpful Hints and Maintenance
• The distilled water and the liquid to be measured
should be at the same temperature.
• Null point should be adjusted once every 30 minutes.
• Clean prism completely to prevent residual impuri-
ties, which could cause error during measuring.
• The refractometer is a precision optical instrument;
handle with care. Do NOT touch the optical surfaces.
• Avoid strong shock during transportation.