VST Lab Coffee 2 User manual
VST inc
Lab Coffee II
Digital Refractometer
Instructions for Base Models
Coffee, Epresso
Coffee & Espresso
Read Instruction Manual Before Use
Rev D
Made in USA
© VST, Inc. 2012
Best New Product
SCAA 2010
Designed to work directly
with VST LAB Coffee Re-
fractometers
Calculate Brew Formula
Portions
Measure extraction yield
against design targets
Conversions for Volumes,
Weights, Metric and US
Units
Works with virtually any
brew method
Design, Brew, Measure,
Save, Share
The VST Laboratory Grade Coffee Refractometer
LAB Grade Precision & Accuracy
Temperature Stability Function
Multiple Measurements
Averaged Display
Coffee and Espresso
Scales Included
Smart Zero-Set Software
Optional Rugged Hard Case
Five Languages
Made in USA
Evaporative Cover &
Ambient Light Shield
Stainless-Steel
Sample Well
Sapphire
Optics
1024 Element
Detector Array
24-Character
Backlit Display
Rubber Armor Jacket
Coffee and Espresso
Design Software
www.MoJoToGo.us
2
Warranty
A. What is covered and for how long:
Any defect in material and workmanship from use in accordance with the
Instruction Manual, for one year from the date of purchase.
B. Who gets the Warranty:
This warranty is limited to the original purchaser of product.
C. What we will do:
If your VST product is defective, we will repair it or, at our option, replace it at no
charge to you. If we repair your VST product, we may use new or reconditioned
replacement parts. If we choose to replace your VST product, we may replace it
with a new or reconditioned one of the same or similar design.
D. Limitations:
DAMAGE FROM LEAKING BATTERIES IS NOTCOVERED BY VST’s
WARRANTY. EXCEPTAS SET FORTHABOVE, NO WARRANTY OF
MERCHANTABILITYOF FITNESS FORAPARTICULAR PURPOSE, OR OTHER
WARRANTY, EXPRESS, IMPLIED OR STATUTORY, NOR ANYAFFIRMATION
OF FACT OR PROMISE IS MADE BYVST WITH RESPECTTO THE GOODS
WHICHARE SOLD PURSUANT HERETO. VSTSHALLNOT BE LIABLE FOR
INCIDENTALOR CONSEQUENTIAL LOSSES, DAMAGES OR EXPENSES,
DIRECTLYOR INDIRECTLYARISING FROM THE SALE, HANDLING, OR USE
OF THE GOODS, OR FROMANY OTHER CAUSE RELATING THERETO,AND
VST’s LIABILITY HEREUNDER IN ANY CASE IS EXPRESSLY LIMITED TO THE
REPAIRAND OR REPLACEMENT (IN THE FORM ORIGINALLY SHIPPED) OF
GOODS NOT COMPLYING WITH THIS AGREEMENT OR,AT VST’s ELECTION,
TO CREDITING BUYER WITHAN AMOUNTEQUALTO THE PURCHASE
PRICE OF SUCH GOODS, WHETHER SUCH CLAIMSARE FOR BREACH OF
WARRANTY, NEGLIGENCE OR
OTHERWISE.
E. How to Obtain Warranty Service:
To obtain warranty service for your VST product, you must provide proof of the
date and place of purchase of the product, and have completed and returned
the Warranty Registration Card to VST. You may obtain service by contacting
product, shipping prepaid, to: VST, inc.,Attention: Service Department, P.O. Box
61, Harvard, MA01451 USA. Be sure to include your name, address, telephone
number, RMAForm, proof of date and place of purchase and a description of the
operating problem. If eligible for repair, VST will repair or, at our option replace,
your VST product and return it to you freight pre-paid if in the 50 U.S. Users
outside of the 50 U.S. must pre-pay return freight.
The above is your exclusive remedy under this warranty.
F. What this Warranty does not cover:
This Warranty does not cover batteries or lost screws (which are considered
replacement parts), defects resulting from accidents, hinged items, damage
while in transit to or from our service location, or damage resulting from leaking
batteries, alterations, falls, misuse or abuse, lack of proper maintenance,
unauthorized repair or modification of the product, affixing of any attachment
not provided with the product, fire, flood or act of God, or failure to follow the
Instruction Manual. This Warranty is the only one we will give on your VST
product, and it sets forth all our responsibilities regarding your VST product. There
are no other express warranties.
14 Specifications
Protected by US Patents and Patents Pending
VST LAB Coffee
Refractometer Models
Coffee Espresso Coffee &
Espresso
Unit of Measure: % TDS % TDS % TDS
Range: 0.00 - 9.99 0.0-20.0 0.00 - 20.00
Resolution: 0.01% 0.1% 0.01%
Precision: +/- 0.02% +/- 0.1% +/- 0.02%
Accuracy: +/- 0.05% +/- 0.1%
0.00-4.99:
+/- 0.05%
5.00-20.00:
+/- 0.10%
Prism Material: Sapphire
Well Material: Stainless Steel w/Cover
Detector: 1024 Elements
Temp Range: 15 to 40 ºC (59 to 104 ºF)
Sample Volume: 0.3 ml
Measuring Time: < 2 Sec (Typical)
Power: 2x AAA
Battery Life: > 4,000 Readings
Dependant on Backlight
Dimensions: 145 x 75 x 37 mm
Weight: 250 grams (8.8 Ounces)
Display: LED Backlight, LCD
2 Lines x 12 Characters
Languages: 5 Languages - English, French,
Spanish, German, Russian
Specifications are subject to change without notice.
3
Optional Accessories
Coffee & Espresso Software for iPhone®, iPad®,
iPod Touch® or PC & Mac under Windows.
See: www.VSTAPPS.com - SOFTWARE
Please refer to www.VSTAPPS.com - Refractometer
ACCESSORIES for
Soft Case - soft silicone case available in multiple colors.
Hard Case - protects instrument during transit, keeps
temperature stable.
Reference Solutions -Accurate to +/- 0.02% for 1.40%
TDS and +/- 0.03% for 9.70% TDS, can be used to check
accuracy of the instrument at 20.0 +/- 2.0 Deg C.
Syringe Filter Kit - For pre-filtering espresso or coffee
brewed using metal filters
Transfer Pipettes - to transfer samples without
contamination to ensure accuracy
4Temperature Correction
The VST LAB Coffee Refractometer is temperature corrected
for aqueous (water-based) coffee and espresso solutions.
Temperature correction does not mean that a hot coffee or
espresso sample can be placed directly into the sample well
which is at ambient temperature. Rather, it means that the
sample should first be cooled to the temperature at which the
instrument was last calibrated, and that both the instrument
and sample are within the temperature correction range of 15
to 40 °C.
In order for temperature correction to work properly, a small
portion of the sample should be placed into a glass that has
been at ambient temperature and allowed 20-30 seconds to
cool before being transferred to the instrument sample well.
Once placed, allow 15-20 seconds for the sample to reach
temperature equilibrium with the instrument.
For the most accurate and repeatable results it is
recommended that the instrument, distilled water used to
calibrate the instrument, glass or ceramic cooling cups, and
the sample to be measured all be at the same temperature and
within the range of 15 to 40 °C.
Samples filtered with the VST COF/ESPsyringe filters will yield
the most stable, repeatable results.
13
Instrument Features
The VST LAB CoffeeII digital refractometers represent
a signifcant improvement in accuracy and precision over
previous models and are satisfactory for laboratory use.
Battery life is double previous models. The instruments feature
a 1,024 element detector array and sapphire prism for superior
resolution and accuracy. Precision is typically +/- 0.01-0.02%.
The two-line backlit LCD display offers improved readability.
The low-power LED backlight auto dims after 20 seconds to
preserve battery life. In newer instruments the backlight dims
during measurement to improve precision, and returns to ON
when the measurement is completed and displayed. You may
turn backlight off for longer battery life, or when batteries are
low to extend remaining life. Amenu function is provided to
disable backlighting. Under typical use, without backlight, a
single set of batteries should last for 4,000 or more readings.
The instrument will automatically power OFF when idle for
three minutes. Measurements are displayed for a full three
minutes before auto-shut down.
TIP:
Hold <GO> for five seconds to turn instrument OFF.
Hold <MENU> for five seconds to display serial number and
firmware version.
The instrument reads each sample multiple times and
displays an averaged value to help eliminate noisey or erratic
measurements.Atemperature stabilization software feature
prevents false calibration if the water sample temperature is
not stable during zero set.
Five languages are supported – English, French, Spanish,
German and Russian.
Accessory jackets and hard cases available for protection to
help ensure the instrument will not be damaged by excessive
shock and vibration during use or transit. High accuracy
reference solutions at 1.40% and 9.70% TDS are available at
www.VSTAPPS.com to verify instrument accuracy.
12 Introduction
The VST LAB Coffee digital refractometers for Coffee &
Espresso TDS are advanced fourth-generation handheld
instruments that put laboratory precision in the palm of
your hand.Accuracy and precision of the VST LAB Coffee
refractometers are comparable to state-of-the-art dehradration
ovens, and rival benchtop laboratory refractometers with
Peltier trays. VST’s latest LAB Coffee refractometers achieve
typical accuracies of +/- 0.03% and precision of +/- 0.02%.
Designed for the rapid and accurate determination of coffee
concentrations, these instruments will automatically correct for
temperature within the range of 15 - 40 °C (59 -104 °F), and
when used and cared for properly, will provide years of trouble-
free service.
This manual will help you maximize the usefulness of your
instrument, and it’s recommended that it be read carefully
before use. If you have any questions, please contact VST
The VST LAB Coffee models are equipped with several scales
that measure coffee concentration from 0-20 %Total Dissolved
Solids. See specifictions for range, resolution, accuracy,
precision and temperature correction.
IMPORTANT:
When measuring espresso or coffee brewed with woven
or mesh metal filters, the sample must be filtered prior to
measurement to remove non-dissolved, suspended solids
using a coffee/espresso syringe filter.
Read the section about Filtering Espresso and Coffee in this
instruction sheet for more information on pre-filtering prior to
making measurements.
5
Calibration - Zero Set
The VST Coffee Refractometer MUST be Zero Set before
initial use and periodically thereafter for changes in ambient
temperature of more than 2 Deg C. It is recommended that a
Zero Set be performed at least once a day as well as prior to
performing tests requiring the highest accuracy, or when moving
between environments with changes in ambient temperature.
Distilled or deionized water is required for Zero Setting the
instrument. The water temperature for zero setting should
be between 15-30°C (59 to 86 °F). To ensure accuracy, it is
important to independently verify that you are calibrating the
instrument with distilled or deionized (DI) water and not just a
clear liquid which you think is DI water. RO (reverse osmosis)
water is not recommended for Zero Set.
1
2
3
4
Inspect the measuring surface to make
sure it is clean and dry. Place a few drops
of distilled water on the measuring surface.
Close the sample cover and allow some
time for the temperature to equalize. The
sample cover MUST be closed to calibrate
or take measurements.
Press and release <GO> to turn the instru-
ment on.
Press and release <MENU> until the
display reads: Set Zero?
[GO] To Set
5Press and release <GO> to automati-
cally zero the instrument. Remember
to clean and dry the measuring
surface after zero-set.
If the calibration was successful the instrument will display
“READY” or “nD 1.3330” otherwise, an error message will be
displayed. In later revisions, the backlight dims during reads.
6
Allow 2 minutes for espresso to cool
and CO2to diffuse out of solution, and
stir sample for 4-5 seconds.
Draw about 3-4 mLespresso with sy-
ringe tip under the crema, and without
touching the bottom
Press GO to take a measurement.
Using a fresh pipette, transfer the
cooled sample to the instrument
Sample Well. Close cover. Allow 20-
30 seconds to equibrilate.
Draw a 0.2 - 0.4 mLfiltered sample
using a pipette and transfer to a clean
dry cup or glass that is at ambi-
ent temperature. Let cool for 30-60
seconds.
Slowly express about 2 mLinto a clean,
dry glass. Allow 30-60 seconds to cool.
CONTINUE with Step 2 of Sampling
Procedure, below.
Attach syringe filter and tighten until
snug, about a quarter turn. Do not
over-tighten.
Sampling Procedure
Filtering Procedure
for Espresso or Coffee
1
1
2
2
3
3
4
11
Filtering Espresso and Coffee
Filtering Espresso
When measuring espresso, you must filter the sample prior to
measurement to remove non-dissolved solids that pass through
metallic filters. Using the incorrect filter or a paper will result in
inaccurate and erratic readings. VST Coffee/Espresso Syringe
filters are designed specifically for espresso and coffee brewed
with any metallic filter, and will ensure accurate and repeatable
TDS measurements with the LAB Coffee Refractometer. Espresso
measurements should be taken no earlier than two minutes after the
shot is extracted, to allow sufficient time for CO2infused into solution
to be released. CO2reduces the density and therefore also the
refractive index, causing lower than actual readings.
Filtering Coffee
Generally, coffee brewed with paper or cloth filters and ground
to nominal drip grades does not need to be filtered prior to
measurement. However, coffee brewed with metal filters such as
press-pot, Clover®, trifecta, or Swiss Gold, or without filters–such
as coffee prepared for cupping, cold-processed or turkish methods,
must be pre-filtered, as above, using the syringe filter before
measurement. Coffee ground at a fine setting or using an espresso
grinder, even if brewed through a paper filter, should be filtered using
a syringe filter prior to measurement.
Note: When comparing % TDS measurements made with a
refractometer to those taken by a dehydration method, the espresso
beverage sample to be dehydrated must also be filtered first,
using a method similar to that recommended, below, so that both
measurements are Total Dissolved Solid measurements, versus total
brew solids, in the case of unfiltered espresso.
One filter is required for each measurement. Do not force more liquid
through a filter that has reached its maximum capacity, or bursting of
the device may occur resulting in loss of sample or personal injury.
IMPORTANT:
When using VST COF/ESPSyringe Filters to prepare a sample for
measurement, be sure to deliver the filtered espresso sample into
a dry, clean glass or cup for cooling to ROOM TEMPERATURE, not
directly into the refractometer sample well.
10
The Span Set function is used by the factory to set a calibration point
toward the upper end of the VST Espresso range. Span Set is used
to determine if a factory RE-CALIBRATION is required, because the
instrument no longer meets specifications.
Normally, Span Set is not required throughout the life of the
instrument, unless it is dropped or subject to other significant shock
and vibration.
If you have reason to believe the instrument is not providing correct
measurements, you can confirm using the VST Reference Solutions.
Maintenance and Upgrade Note:
Most VST LAB Coffee refractometers may be upgraded to latest
firmware revision and re-calibrated for a fixed fee of $199 (or current
fee). Other repairs, if needed, are not included in this charge. For
firmware upgrades, latest fees, and re-calibration services, contact
VST with your serial number, proof and date of purchase and request
an RMAprior to returning your instrument to VST.
Reference Solutions -Accurate to +/- 0.02% for 1.40%
TDS and +/- 0.03% for 9.70% TDS, are be used to check
accuracy of the instrument at 20.0 +/- 2.0 Deg C, and are
available from:
www.VSTAPPS.com
for calibration reference fluids.
Calibration - Span Set 7
Menu Options
Various options are accessible through the <MENU>
button. With the instrument “ON”, press and release
<MENU> to step through the options.
COFFEE % TDS –press [GO] to Set
This option sets the default unit of measure, or scale,
the instrument will read. Some instruments are
programmed with more than one scale, or a separate
ESPRESSO % TDS scale. Later revision instruments
have a single COFFEE % TDS scale that covers the
entire range of coffee through espresso. Pressing
<MENU> will step through all available scales. Press
<GO> to set the a scale as the default.
SET ZERO?–press [GO] to Set
The Zero Set option will zero or calibrate the
instrument to pure water. See “Calibration - Zero Set.”
Set Span?–press [GO] to Set
The Span Set option will calibrate the upper range of
the instrument to a special calibration solution. See
“Calibration - Span Set.”
LCD-Light?–press [GO] YES
This option allows you to turn the LCD display
backlight on or off.The options are “Yes” and “NO.” Later
revision instruments turn backlight OFF momentarily
during read.
Language?–press [GO] to Set
This option allows you to set the display to a particular
language; English, Spanish, German, French, or
Russian. Just follow the prompts to your language of
choice and press <GO> to set.
8
Follow the steps below to accurately measure a coffee or
espresso sample:
Taking a Measurement
1
2
3
5
Inspect the measuring surface to make sure
it is clean and dry. Place a few drops of the
sample to be tested on the measuring surface.
The instrument need not be on.
Close the sample cover and allow some time
for the temperature to equalize.Agood rule-
of-thumb is to wait 10 to 20 seconds for the
sample to equilibrate to the temperature
of the instrument.
Asingle press and release of <GO> will turn
the instrument on.
Press <GO> a second time to start the mea-
surement. The display will indicate Coffee %
TDS or Espresso % TDS on the first line of the
display and * READING * on the second line.
On later revisions backlight turns OFF mo-
mentarily during a measurement.
Notes:
The instrument will not take a measurement
if it detects the sample was at a significantly
different temperature than the prism.An error
message “TEMPERATURE STABLE ERROR”
will be displayed.
The reading will take approximately 2-3
seconds and the result displayed on the
screen is the average of several
measurements.
for calibration reference fluids.
4
9
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