On our led online store, We are selling Digital Refractometer, Hand-held Refractometer, Hand Held Refractometer, Illumination Hand Held Refractometer, Abbe Refractometer, Bench-top Refractometer, Gem Refractometer, Gemological Refractometer and so on.
A refractometer is a laboratory or field device for the measurement of an index of refraction (refractometry). The index of refraction is calculated from Snell's law and can be calculated from the composition of the material using the Gladstone–Dale relation.
A refractometer is an optical device that, like a
hydrometer, measures the specific gravity of your beer
or fort. It does so by sampling a small amount of
liquid, and looking at its optically. The main advantage
over a hydrometer is the small sample size needed –
typically only a few drops.
If you start with a glass of clear water, you will
notice that the water and glass bend the light passing
through it in a certain way. The bending of the light by
the water is called refraction. Light bends to different
degrees as it passes through different substances. This
is the same effect that glasses lenses in eyeglasses are
based upon – the lenses bend the light allowing glasses
to adjust the focus of an image and make it clearer to
your eyes.
If you add sugar to your glass of water, the light will
bend more. The refractometer takes advantage of this
effect to measure the amount of bending (refraction)
which indicates the amount of sugar in the sample. Most
refractometers use a prism and a light source to
illuminate the sample. On inexpensive refractometers,
you hold the instrument up to a natural light source.
More expensive models have internal light sources.
Most brewing refractometers measure samples in Brix,
which is a scale used to measure specific gravity
primarily by wine makers. Some also use a Refractive
Index (RI) scale. Both the Brix and RI indexes need to
be converted to standard specific gravity or Plato
scales using a formula, as wort does not have the same
reflective properties as plain sugar water.
There are four main types of refractometers: traditional
handheld refractometers, digital handheld
refractometers, laboratory or Abbe refractometers, and
inline process refractometers. There is also the
Rayleigh Refractometer used (typically) for measuring
the refractive indices of gases.
In veterinary medicine, a refractometer is used to
measure the total plasma protein in a blood sample and
urine specific gravity.
In drug diagnostics, a refractometer is used to measure
the specific gravity in human urine.
In gemology, a refractometer is used to help identify
gem materials by measuring their refractive index.
In marine aquarium keeping, a refractometer is used to
measure the salinity and specific gravity of the water.
Buying Tips
When you purchase a refractometer, you'll need to know:
•The range of readings (highest to lowest), to make sure
it will suit your purpose. A standard range for home
brewers is 0 to 32% Brix. For example, in order to
achieve a 13% wine, you'll want to start your wine at a
Brix of 23.
•The ease with which the refractometer can be read and
understood. Some less expensive refractometers are
difficult to read, either due to a lack of a focus
adjustment, inferior optics, or the eyepiece lacks a
rubber seal and will not fit snugly over your eye.
•The calibration temperature of the refractometer. The
most common calibration temp is 20° C or 68° F. If your
sample is not exactly 68° F, you will need to make
mathematical corrections to compensate for the
temperature difference. Luckily, many modern models of
refractometers (like the ones stocked by grapestompers)
are sold with ATC (automatic temperature compensation),
so you never have to worry about the temperature of your
sample.
•How easy it is to calibrate. Must you purchase a
calibration liquid, or can you calibrate with distilled
water? Does it calibrate with a set screw or a dial or
knob?
•How easy it is to clean.
•If it comes with a protective case (they're pretty
fragile) and instruction manual.
Conclusion
There are many reasons why a winemaker might want to use
a refractometer:
•To measure the percentage Brix of grapes or other fresh
fruit
•To determine progress of crop ripening
•To measure progress of fermentation
•To measure the amount of sugar present in grapes or
other fruit
•To allow the winemaker to determine when fruit is at
its peak of ripeness and should be harvested
The top 10 most frequently asked questions about our traditional hand-held refractometers.
"Why is the scale completely dark?"
Unless you have a fluid sample on the measuring surface
the inside of the instrument will be dark and you will
not see the scale or a shadowline.
"Why is the scale completely bright?"
If you cannot see the shadowline and the whole scale is
illuminated, then the sample you are testing is above
the range of the instrument.
"How do I turn the light on?"
To activate the light on the ViewPoint Illuminator
gently press the spot on the label marked "PRESS FOR
LIGHT." Remember there are no dumb questions. If the
light doesn't work, the battery may be dead. If this is
the case, please send the instrument back to us and we
can replace the ViewPoint.
"How do I know if my instrument is in calibration?"
Most instruments have a scale division that is
equivalent to water. in the case of a Brix
refractometer, it is 0.0 Brix, and on the Glycol &
Battery Tester, it is +32 degrees. This is the reading
you should get when testing water at room temperature.
If the reading for water does not equal one of the above
values, then you need to recalibrate your instrument.
"I hear a rattle inside whenever I shake it."
Then don't shake it - just kidding. A rattle most likely
means that one of the internal optical components came
loose inside. This is usually caused by dropping the
instrument. Please send the instrument to our repair
department. There is nothing you can do in the field to
repair it. In the future remember that this is a
precision optical instrument. Although we try to make
refractometers as rugged as we can, please try to handle
them as you would a pair of binoculars or a camera.
"How do I know what instrument I need?"
If you are uncertain about which model refractometer you
need to test a particular fluid, just call us. We more
than likely have experience measuring that fluid. If we
can't help you over the phone, we will happily test your
fluid in our laboratory FOR FREE to determine which
refractometer is best for your needs.
"Can I get a certified calibration?"
We have a dedicated laboratory and trained staff that
will happily test your refractometer and issue a
certificate of calibration traceable to NIST.
"How do I replace my ViewPoint Illuminator?"
The ViewPoint illuminator has a built-in coin cell
battery with a ten-year shelf life. It is designed for
between 3,000-5,000 fifteen-second uses. In the event
the battery dies, just send your entire instrument to
MISCO, and we will replace the ViewPoint for you. You
may also order a replacement online and change it
yourself. Do not try to disassemble the ViewPoint, there
are no user serviceable parts inside.
"What is the difference between freezepoint and burst
point?"
Freezepoint is the point that the first ice crystals
form in the absence of supercooling. Burst point is the
point that the solution freezes solid and bursts the
vessel containing it. The burst point is usually 30-50
degrees colder than the freezepoint. Our Glycol &
Battery Tester reads the freezepoint of both ethylene
and propylene glycol solutions. If you need to know the
burst point, take a reading on the Glycol & Battery
Tester and use a chart (available from your antifreeze
supplier) to cross-reference freezepoint to burst point
or percent concentration.
"I need to know the percent volume of my glycol?"
To ascertain the percent concentration of glycol in a
system, obtain a chart of physical properties from your
glycol supplier. Take a reading with the Glycol &
Battery Tester and cross reference the freezepoint
reading to the percent volume column on the chart.
Digital Fiberoptic Refractometer (DFR) - Top 10
The top 10 most frequently asked questions about the Digital Fiberoptic Refractometer
"How do I turn it off?"
The refractometer will power off automatically after
three minutes of inactivity. To manually shut off the
instrument, hold the ON/CLEAR button down for 3-5
seconds.
"How do I change the scales?"
Pressing the SELECT button will cycle through all the
possible scale choices on the instrument. If you want to
permanently change the instrument scales, you may send
it back to us and we will be happy to reprogram it for
you for a slight charge.
"Why does my instrument read [BRIGHT +]?"
A reading of [ BRIGHT + ] indicates the optical sensor
is being overpowered by strong ambient light. If this
happens, shade the sensor or move to a less brightly lit
area and repeat the measurement.
"Why does my instrument read [TEMP]?"
A reading of [ TEMP ] indicates the fluid or instrument
temperature is above or below the range of the
instrument.
"Why does my instrument read [RANGE +/-]?"
A reading of [ RANGE +/- ] indicates that the
measurement is above or below the range of the current
scale. If the instrument periodically reads [RANGE -],
make sure you haven't trapped a small bubble in the
sensing area. A bubble directly over the sensing area
can cause the instrument to display [RANGE -].
"Why does my instrument read [CALIBRTE]?"
A reading of [ CALIBRTE ] indicates the instrument needs
to be calibrated. The spelling error is intentional
since we can only display eight characters.
"Why does my instrument read [LOW BATT]?"
A reading of [ LOW BATT ] indicates the battery needs to
be replaced. Make sure you observe the battery polarity
when changing the battery.
"How often should I calibrate?"
It is recommended that the instrument be calibrated at
least once a day, prior to performing any test requiring
the highest precision, or when moving between
environments with extreme changes in ambient
temperature.
"Why won't it turn on?"
If your instrument won't power on, check the battery
polarity. If the polarity is correct and the instrument
will still not power on, change the battery.