VST Lab Coffee 2 User Manual

Filtering Espresso and Coffee
Filtering Espresso
When measuring espresso, you must fi lter the sample prior to
measurement to remove non-dissolved solids that pass through
metallic fi lters. Using the incorrect fi lter or a paper will result in
inaccurate and erratic readings. VST Coffee/Espresso Syringe
fi lters are designed specifi cally for espresso and coffee brewed
with any metallic fi lter, 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 suffi cient time for CO
2
infused into solution
to be released. CO
2
reduces the density and therefore also the
refractive index, causing lower than actual readings.
Filtering Coffee
Generally, coffee brewed with paper or cloth fi lters and ground
to nominal drip grades does not need to be fi ltered prior to
measurement. However, coffee brewed with metal fi lters such as
press-pot, Clover®, trifecta, or Swiss Gold, or without fi lters–such
as coffee prepared for cupping, cold-processed or turkish methods,
must be pre-fi ltered, as above, using the syringe fi lter before
measurement. Coffee ground at a fi ne setting or using an espresso
grinder, even if brewed through a paper fi lter, should be fi ltered using
a syringe fi lter 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 fi ltered fi rst,
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 unfi ltered espresso.
One fi lter is required for each measurement. Do not force more liquid
through a fi lter 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/ESP Syringe Filters to prepare a sample for
measurement, be sure to deliver the fi ltered 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 specifi cations.
Normally, Span Set is not required throughout the life of the
instrument, unless it is dropped or subject to other signifi cant shock
and vibration.
If you have reason to believe the instrument is not providing correct
measurements, you can confi rm using the VST Reference Solutions.
Maintenance and Upgrade Note:
Most VST LAB Coffee refractometers may be upgraded to latest
fi rmware revision and re-calibrated for a fi xed fee of $199 (or current
fee). Other repairs, if needed, are not included in this charge. For
fi rmware upgrades, latest fees, and re-calibration services, contact
VST with your serial number, proof and date of purchase and request
an RMA prior 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
Contact VST at support@vstapps.com
for calibration reference fl uids.
Calibration - Span Set
7

VST Lab Coffee 2 Specifications

General

Brand	VST
Model	Lab Coffee 2
Category	Measuring Instruments
Language	English