Milwaukee MA881 User manual

INSTRUCTION MANUAL
SATISFACTION
GUARANTEED
MA881
Digital Invert Sugar
Refractometer

All rights are reserved. Reproduction in whole or in part is
prohibited without the written consent of the copyright owner,
Milwaukee Instruments Inc., Rocky Mount, NC27804USA.
THANK YOU for choosing Milwaukee Instruments!
This instruction manual will provide you the necessary
information for correct use of the meters.

3
TABLE OF CONTENTS
1. FUNCTIONAL DESCRIPTION.................................................................................4
2. GENERAL DESCRIPTION........................................................................................6
3. SPECIFICATIONS.........................................................................................................7
4. PRINCIPLE OF OPERATION...................................................................................8
5. MEASUREMENT GUIDELINES.............................................................................9
6. CALIBRATION PROCEDURE................................................................................ 10
7. MEASUREMENT PROCEDURE.............................................................................12
8. CHANGING TEMPERATURE UNIT.................................................................... 14
9. ERROR MESSAGES................................................................................................. 15
10. BATTERY REPLACEMENT...................................................................................17
CERTIFICATION.............................................................................................................. 18
RECOMMENDATION.................................................................................................... 18
WARRANTY...................................................................................................................... 18

4MA881 Digital Invert Sugar Refractometer
1. FUNCTIONAL DESCRIPTION
DISPLAY
A. BATTERY STATUS ICON
(BLINKS WHEN LOW BATTERY CONDITION DETECTED)
B. MEASUREMENT IN PROGRESS TAG
C. SETUP: FACTORY CALIBRATION TAG
D. CAL: CALIBRATION TAG
E. PRIMARY DISPLAY
(DISPLAYS MEASUREMENT AND ERROR MESSAGES)
F. AUTOMATIC TEMPERATURE COMPENSATION
(BLINKS WHEN TEMPERATURE EXCEEDS 10-40 °C / 50-104 °F
RANGE)
G. TEMPERATURE UNITS
H. SECONDARY DISPLAY
(DISPLAYS TEMPERATURE MEASUREMENTS;
WHEN BLINKING, TEMPERATURE HAS EXCEEDED OPERATION
RANGE: 0-80 °C / 32-176 °F)

FUNCTIONAL DESCRIPTION 5
FRONT PANEL
MA881
Digital Invert Sugar Refractometer
0 to 85 %Mass
A E F G
B C D
A. LIQUID CRYSTAL DISPLAY (LCD)
B. READ KEY (USER MEASUREMENT)
C. ZERO KEY (USER CALIBRATION)
D. ON/OFF
E. PRIMARY DISPLAY
F. SECONDARY DISPLAY
G. STAINLESS STEEL SAMPLE WELL AND PRISM
BOTTOM
H
I
H. BATTERY COVER
I. BATTERY COMPARTMENT

6MA881 Digital Invert Sugar Refractometer
2. GENERAL DESCRIPTION
SIGNIFICANCE OF USE
Thank you for choosing Milwaukee. This instruction manual will
provide you the necessary information for correct use of the meter.
The MA881 is an optical instrument that employs the measurement
of refractive index to determine the % Invert Sugar in aqueous
solutions. The method is both simple and quick. Samples are
measured after a simple user calibration with deionized or distilled
water. Within seconds the instrument measures the refractive
index of the sample and converts it to % by weight concentration
units. The MA881 digital refractometer eliminates the uncertainity
associated with mechanical refractometers and is easily portable
for measurements in the field.
The measurement technique and temperature compensation
employ methodology recommended in the ICUMSA Methods Book
(Internationally recognized body for Sugar Analysis).
Temperature (in °C or °F) is displayed simultaneously with the
measurement on the large dual level display along with icons for
Low Power and other helpful message codes.
Key features include:
yDual-level LCD
yAutomatic Temperature Compensation (ATC)
yEasy setup and storage
yBattery operation with Low Power indicator (BEPS)
yAutomatically turns o after 3 minutes of non-use.
Remove the instrument from the packing materials and examine
carefully to ensure no damage has occurred during shipping. If
any damage has occurred, notify your Dealer.
Each MA881 instrument is supplied with:
y9 V battery
yInstruction manual
Note: Save all packing material until you are sure that the
instrument functions correctly. A defective instrument must be
returned in its original packing.

SPECIFICATIONS 7
3. SPECIFICATIONS
Range 0 to 85% 0 to 80 °C (32 to 175 °F)
Resolution 0.1% 0.1 °C (0.1 °F)
Accuracy ± 0.2% ± 0.3 °C (± 0.5 °F)
Light Source Yellow LED
Measurement Time Approximately 1.5 seconds
Minimum Sample Volume 100 µL (cover prism totally)
Sample Cell SS ring and flint glass prism
Temperature
Compensation
Automatic between 10 and 40 °C
(50 to 104 °F)
Case Material ABS
Enclosure Rating IP 65
Battery Type/Life 1 x 9 volt AA batteries / 5000 readings
Auto-Shut o After 3 minutes of non-use
Dimensions 19.2 x 10.2 x 6.7 cm (7.5 x 4 x 2.6")
Weight 420 g (14.8 oz.).

8MA881 Digital Invert Sugar Refractometer
4. PRINCIPLE OF OPERATION
TheInvert sugardetermination is madeby measuringthe refractive
index of a solution. Refractive Index is an optical characteristic of a
substance and the number of dissolved particles in it. Refractive
Index is defined as the ratio of the speed of light in empty space
to the speed of light in the substance. A result of this property is
that light will “bend”, or change direction, when it travels through
a substance of dierent refractive index. This is called refraction.
When passing from a material with a higher to lower refractive
index, there is a critical angle at which an incoming beam of
light can no longer refract, but will instead be reflected o the
interface. The critical angle can be used to easily calculate the
refractive index according to the equation:
sin (θcritical) = n2/ n1
Where n2is the refractive index of the lower-density medium; n1is
the refractive index of the higher-density medium.
i
r
n1
n2
= angle of incidence
= angle of refraction
n1 , n2 - refractive index
Refraction Critical Angle Total Internal Reflection
r
i
i critical
i
r
n2
n1
n2
i
i critical
i critical
< >
=
n1
θ
θ
θ
θ
θ θ
θ
θ
θ
θ θ
θ θ
In the MA881, light from an LED passes through a prism in contact
with the sample. An image sensor determines the critical angle
at which the light is no longer refracted through the sample. The
MA881 automatically applies temperature compensation to the
measurement and converts the refractive index of the sample to
Invert sugar concentration in units of percent (by weight).
Prism
Lens
Linear Image Sensor
Sample
Shadow
Led
Sample Well

MEASUREMENT GUIDELINES 9
5. MEASUREMENT GUIDELINES
yHandle instrument carefully. Do not drop.
yDo not immerse instrument under water.
yDo not spray water to any part of instrument except the
“sample well” located over the prism.
yThe instrument is intended to measure seawater solutions. Do
not expose instrument or prism to solvents that will damage
it. This includes most organic solvents and extremely hot or
cold solutions.
yParticulate matter in a sample may scratch the prism. Absorb
sample with a soft tissue and rinse sample well with deionized
or distilled water between samples.
yUse plastic pipettes to transfer all solutions. Do not use
metallic tools such as needles, spoons or tweezers as these
will scratch the prism.

10 MA881 Digital Invert Sugar Refractometer
6. CALIBRATION PROCEDURE
Calibration should be performed daily, before measurements are
made, when the battery has been replaced, or between a long
series of measurements.
1. Press the ON/OFF key, then release. Two instrument test
screens will be displayed briefly; an “all segment” screen
followed by the percentage of remaining battery life. When
LCD displays dashes, the instrument is ready.
2. Using plastic pipettes, fill the sample well with distilled or
deionized water.
Note: If the ZERO sample is subject to intense light such as
sunlight or another strong source, cover the sample well with
your hand or other shade during the calibration.