Biolin Scientific Sigma 702 Product information sheet

Sigma 702
User Manual
Original instructions
Force Tensiometer
MANUAL23834-4

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Table of Contents
1. INTRODUCTION 4
2. SAFETY 5
3. PHYSICAL DESCRIPTION 7
3.1 Measurement Unit 7
3.1.1 Main Body 7
3.1.2 Balance 7
3.1.3 Lifting System 7
3.1.4 Measuring stage 7
3.1.5 LCD Display 7
3.1.6 Manual Membrane Keyboard 8
3.2 Optional Accessories 9
3.2.1 Du Noüy Ring 9
3.2.2 Wilhelmy Plate 9
3.2.3 Density Probe 10
3.2.4 Thermostatic Vessel 10
3.3 Cleaning procedure 11
3.4 Maintenance 11
4. TECHNICAL SPECIFICATIONS 12
5. MEASUREMENT 13
5.1 Preparations for measurement 13
5.2 Measuring surface tension with a Du Noüy ring 14
5.2.1 Choosing a correction method: Huh-Mason or Zuidema-Waters 15
5.3 Measuring interfacial tension with a Du Noüy ring 16
5.3.1 Push Mode and normal (pull) mode 16
5.3.2 Measurement steps 16
5.4 Surface tension measurement with a Wilhelmy Plate 17
5.4.1 Steps for measurement 17
5.4.2 Taring modes: Wet Taring and Dry Taring 18
5.5 Density measurement 18
5.5.1 Density of a liquid 18
5.5.2 Density of a solid object 19
5.6 Collecting data to a PC 19

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5.7 Using the optional printer 20
6. CALIBRATION OF SIGMA 702 21
6.1 Calibration of the electromagnetic balance 21
6.1.1 Calibration procedure 21
6.1.2 Calibration result verification 21
6.2 Calibration of the density measurement system 22
7. TROUBLESHOOTING 23
8. CONTACT AND SUPPORT 24
9. EC DECLARATION OF CONFORMITY 25

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1.Introduction
The Sigma tensiometer system is a high performance tensiometer for the measurement of surface
or interfacial tension. The 702 is designed for measuring surface tensions and interfacial tensions
between two liquids with Du Noüy ring or Wilhelmy plate. The density of a liquid can also be
measured.
Inside this manual you will find information on how to use your Sigma tensiometer. You will also
find brief reviews of the concepts involved in your measurements and some practical advice on the
techniques involved. In order to obtain the maximum performance from your instrument you
should read this manual and keep it available for reference.

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2.Safety
WARNING!
The safety requirements listed in this manual must be followed in order to avoid
personal injury and damage to the instrument. If the equipment is used in a manner
not listed in this manual, protection provided by the equipment may be impaired.
WARNING!
RISK OF ELECTRICAL SHOCK. Do not connect this instrument to electrical power if
the enclosure is damaged or any of the covers or panels are removed. Make sure the
voltage rating on the instrument matches the line voltage available. Make sure the
power cord is not damaged and it is properly connected to the instrument and a
power outlet with protective earthing. Make sure that the power cord is easily
accessible after the equipment has been installed and set at its working position.
WARNING!
RISK OF ELECTRICAL SHOCK OR FIRE HAZARD. The instrument has been
designed for indoor use only. Do not expose it to rain, snow or dust. During storage
or transport the instrument should be kept dry. Temperatures below 0˚C and above
70˚C should be avoided. Do not operate at ambient temperatures below 15˚C and
above 30˚C.
When handling flammable liquids, use a minimum sample volume that is required for
successful measurement.
Ensure prevention of Electrostatic Discharge (ESD) when handling flammable liquids.
Contact your local authorities for information on ESD prevention practices.
Do not heat flammable sample liquids to temperatures higher than T–25 °C where T
is fire point of the sample liquid.
WARNING!
RISK OF INJURY. Do not configure the instrument with parts that are not supplied
by Biolin Scientific and not intended to be used with Attension instruments. Do not
install substitute parts that are not described in this manual. Do not perform any
modifications to the product.
If dangerous liquids are used, adequate protection such as proper ventilation, safety
glasses, etc., should be used: refer to the safety information from the supplier and
general safety regulations in your country. Carry out appropriate decontamination if
equipment is exposed to hazardous material.
WARNING!
RISK OF BURNS. Exercise caution when touching heated sample vessels (optional).
The vessel surface will reach dangerous temperatures when heated. The vessels are
marked with hot surface warning symbol.
Platinum Wilhelmy plate/rod is an excellent catalyst for oxidation of methanol vapor.
This reaction is very exothermic. In experiments in which the Wilhelmy plate/rod is
positioned above reagent-grade methanol this reaction may cause dangerous
heating of the plate/rod. Be aware of this phenomenon and take appropriate
precautions.

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CAUTION!
Make sure that the power is switched off when making any electrical connections
(apart from the USB cables). Connecting cables with power on may damage
instrument electronics. To disconnect the instrument, after turning the instrument
off, remove the power cord plug from the electric outlet.

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3.Physical Description
This section describes the physical construction of the Sigma 702 tensiometer. All necessary
hardware, software and accessories are included in the basic Sigma instrument making it possible
to take the instrument into use directly from its shipping crate.
CAUTION!: The transportation lock of the balance must be unlocked before using the instrument.
See section 3.1.2 for instructions.
3.1 Measurement Unit
The basic Measurement Unit consists of the following parts:
Main body containing electronics, power supply and user interface
Manually locked and calibrated super sensitive electro-magnetic balance
Lifting stage with long movement range for large samples
Membrane keyboard for manual system operations without PC control
Led lights for non-heating illumination of the measuring chamber
3.1.1 Main Body
The Main Body consists of the Power supply and the Main Electronic Board.
3.1.2 Balance
The balance for your Sigma 702 tensiometer is located in the upper housing of the Measuring Unit.
The balance is suitable for all kind of surface or interfacial tension measurements. One hook comes
down from the balance. This is used for hanging the probe used for the measurement. The travel
lock is located below the balance housing and looks like a small screw. Use this to lock the balance
when the Measuring Unit is moved (even from table to table). It is important to unlock the
transportation lock before using the instrument. To unlock, turn the screw so that it moves
outwards from the balance housing.
3.1.3 Lifting System
The stage of your Sigma tensiometer is lifted by a stepper motor. The speed range for the
movement of the sample stage is from 0.01 to 500 mm/min in increments of 0.01 mm/min. The
maximum range of movement is 100 mm. There are safety switches which stop the upward and
downward movement of your stage automatically at the highest and lowest positions of the stage.
3.1.4 Measuring stage
The measuring stage of your Sigma tensiometer has been designed so that it has a sufficient
separation between balance housing (top) and measuring stage for improved stability.
3.1.5 LCD Display
The built-in LCD display is used to monitor the status of the Sigma 702. It guides the user to the
next step in the measurement or calibration procedure and shows the results obtained.

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Figure 1: Startup screen
The bottom line of the display shows the balance reading, which is updated real-time. During
measurement, the bottom line shows the surface tension or interfacial tension value calculated
from the balance reading.
Figure 2: Adjusting measurement parameters
3.1.6 Manual Membrane Keyboard
The built-in Manual Membrane Keyboard allows the user to navigate through the menus of the user
interface and to control sample stage movement and the stirrer.
Figure 3: The manual membrane keyboard controls
To control the distance between the probe and the vessel, use the triangular buttons on the left
side of the keyboard. The upper triangle moves the stage up, the lower one moves it down. Press
and hold down a button to keep the stage moving. To save time, it is advisable to bring the liquid
surface close to the probe before starting measurement. The stage buttons are disabled during a
measurement.
The button with two arrows in circular shape in the lower middle part of the keyboard is the stirrer
button. Pressing it sets the stirrer on and off. The button is disabled during a measurement.

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The blue buttons OK, , and Stop/Cancel are used to navigate the menus on screen. Press
and to move the highlight on the desired operation and OK to select it. Stop/Cancel can be
used to return back to an upper menu level or to interrupt any operation.
3.2 Optional Accessories
Note: You need at least one of the probes described in sections 2.8.1 through 2.8.3 to perform
measurements with Sigma 702.
3.2.1 Du Noüy Ring
A platinum-iridium ring (Du Noüy ring) can be purchased separately for use in surface tension and
interfacial tension measurements. The ring should be cleaned regularly after use and treated
carefully to avoid deformation.
A good way to store the ring is to immerse it in ethanol by first hanging it on a hook attached to a
lid, which is then attached to a beaker filled half-full with ethanol. Then before using the ring again
flush it with pure ethanol and water, or burn it with a Bunsen burner (ca. 1000ºC flame) for a short
time (glowing yellow-red for a few seconds). In this way the ring will keep its form better and will
not deform as easily as by putting it back to the transport case after each measurement.
Figure 4: Du Noüy ring
3.2.2 Wilhelmy Plate
A thin platinum plate (Wilhelmy plate) can be purchased separately for surface tension
measurement. The measurement with Wilhelmy plate is based on measuring the increase in the
weight that the plate gets when it is wetted and water "hangs" from it (see figure 5). The force per
wetted length is proportional to the surface tension. In this case, wetted length is the perimeter of
the plate.
The Wilhelmy method is based on the assumption that the contact angle between the plate and the
liquid is zero.

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Figure 5. Water "hanging" from a Wilhelmy plate, increasing its weight.
A Wilhelmy plate can be cleaned by washing it with pure ethanol and de-ionized water. The plate
should also be burned glowing red with a Bunsen burner for a few seconds in order to burn all
remaining organic contaminants.
WARNING!
RISK OF BURNS. Platinum Wilhelmy plate/rod is an excellent catalyst for oxidation
of methanol vapor. This reaction is very exothermic. In experiments in which the
Wilhelmy plate/rod is positioned above reagent-grade methanol this reaction may
cause dangerous heating of the plate/rod. Be aware of this phenomenon and take
appropriate precautions.
3.2.3 Density Probe
A density probe (a glass ball with a wire hook attached to it) can be purchased separately for use
for density measurement with Sigma 702. The hook of the probe is mounted to the hook that
hangs from the balance housing.
The density measurement system of Sigma 702 must be calibrated for each density probe used.
3.2.4 Thermostatic Vessel
A thermostatic vessel is used for controlling the temperature of the sample liquid. It has two water
jackets that conduct water from an external bath/circulator heating or cooling. A glass vessel
should be used inside the thermostatic vessel. Sample vessels with a diameter of 70mm or less fit
in the thermostatic vessel. Note: The necessary external bath/circulator is not included.
Figure 6: Thermostatic vessel