Sample Well
5 Character
LCD
Read Key
Calibrate Key
Mode Key
Battery Door
VST
COFFEE
Refractometer
User Guide
INTRODUCTION:
VST, Inc. would like to extend our appreciation to you for purchasing
this coffee refractometer. It is our mission to provide a quality product
at a very competitive price to our end users and we feel this instru-
ment will prove its value time and again to you.
FEATURES:
CLEANING:
Cleaning of the measurement surface and well should be performed
immediately after each sample reading. Never immerse the instru-
ment in any liquid. When the measurement surface and well have
been completely cleaned no residue should be present.
To properly clean the sample well and glass measurement surface
use a mild soap and water solution, Isopropyl Alcohol or Methanol
followed by a distilled water rinse and then thoroughly dry with a soft
lint and residue free cloth or a product such as KimTech tissues.
To clean the refractometer’s body use a soft cloth with a mild clean-
ing solution like window cleaner applied to it and wipe it clean. Never
use any harsh cleaning agents that will damage the instrument.
Never use any harsh solvents on the instrument that will adversely
affect the material that it is made from.
AUTOMATIC TEMPERATURE COMPENSATION:
Automatic temperature compensation corrects readings over a range
of temperatures. As an example: Samples taken within the working
temperature range of the instrument (15-30 Deg C) are corrected to
a reference temperature of 20 degrees C. Temperature correction is
essential because refractive index varies inversely with temperature.
This feature is used in lieu of temperature control of the prism and
sample. For this feature to be effective however it is necessary to al-
low the sample to temperature equilibrate to the ambient temperature
of the prism.
Finally, for the most accurate and consistent results, coffee TDS
readings should be taken within +/- 2 Deg C of the CALIBRATION
temperature using distilled water.
SIMPLE SET UP:
Install Batteries
1. Remove battery door by rotating it the counter-clockwise to the
OPEN position until it stops and lift it off. Do not apply excessive
force.
2. Install batteries, negative side into cavity rst, positive facing
outward.
3. Re-install battery door by rotating the cover in the clock wise
direction until it is in the position shown below.
PRECAUTIONS:
1. Do not use Acetone, Acetone based products or other harsh sol
vents when cleaning the body or it’s components.
2. Using strong solvents such as N-Nimethylacetamide, cresols,
phenols and other tar acids should be avoided, Tetrahydrofuran
or some other lacquer thinners and their components will deterio
rate the prism seal and should not be used.
3. Do not apply excessive force when removing or installing the
battery door.
4. Do not store refractometer in extremely warm or cold environ-
ments.
OPEN
CLOSED
CALIBRATION USING DISTILLED OR DEIONIZED WATER:
1. Clean the measuring surface and well as outlined under “Cleaning”.
2. Apply approximately 0.2-mL DI water to the measurement surface.
3. Allow the water sample to temperature equilibrate to the tempera-
ture of the instrument. (20-25 Deg C, approx 1-2 minutes).
4. Press and hold the “CAL” key for at least 5 seconds.
5. While holding the “CAL” key press the “READ” key, then release
both keys.
6. Successful calibration will be indicated by the word “END” being
displayed. Dry the sample well using KimTech or similar tissues.
7. Select nD using the Mode Key, and take a measurement. Check
the nD at Temperature indicated against the DI Water Table, below.
If the nD does not agree, clean and dry the sample well and glass,
and place another sample of DI water, and wait 1-2 minutes to
equibrilate, then CALIBRATE. When END is reached, take another
nD reading. The reading should agree to the table, within +/-
0.0002 nD for the temperature indicated.
DISTILLED WATER REFRACTIVE INDEX TABLE:
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