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KERN & Sohn GmbHZiegelei 1D-72336 Balingen

E-Mail: info@kern-sohn.com

Tel: +49-[0]7433- 9933-0Fax: +49-[0]7433-9933-149

Internet: www.kern-sohn.com

Operating InstructionsDensity Determination Set for

Analytical Balance KERN ABTKERN ABT-A01Version 1.002/2007GB

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GB

KERN ABT-A01Version 1.0 2/2007Operating Manual

Density Determination Set for Analytical Balance KERN ABT

Contents:

1 INTRODUCTION ............................................................................................................................ 4

1.1 SCOPE OF DELIVERY................................................................................................................. 5

2 INSTALLING THE DENSITY DETERMINATION SET .................................................................. 7

3 PRINCIPLE OF DENSITY DETERMINATION............................................................................... 9

3.1 INFLUENCING MAGNITUDES AND ERROR SOURCES .................................................................... 104 DENSITY DETERMINATION OF SOLIDS................................................................................... 11

4.1 ACTIVATE FUNCTION ............................................................................................................... 124.2 ENTERING DENSITY FOR FLUID................................................................................................ 134.3 CARRYING OUT MEASUREMENT .............................................................................................. 14

5 DETERMINING DENSITY OF LIQUIDS ...................................................................................... 14

5.1 ACTIVATE FUNCTION ............................................................................................................... 145.2 ENTERING DENSITY OF GLASS PLUMMET................................................................................. 165.3 CARRYING OUT MEASUREMENT .............................................................................................. 17

6 PRECONDITIONS FOR PRECISE MEASUREMENTS............................................................... 18

6.1 CALCULATION OF RESULTS ..................................................................................................... 186.2 INFLUENCE FACTORS FOR MEASUREMENT ERRORS ................................................................. 19

6.2.1 Air bubbles....................................................................................................................... 196.2.2 Solid Specimen................................................................................................................ 196.2.3 Liquids.............................................................................................................................. 196.2.4 Surface............................................................................................................................. 196.2.5 Glass Plummet for Measuring Fluids............................................................................... 20

6.3 GENERAL INFORMATION .......................................................................................................... 206.3.1 Density / Relative Density................................................................................................ 206.3.2 Drift of Balance Display ................................................................................................... 20

7 DENSITY TABLE FOR FLUIDS................................................................................................... 21

8 UNCERTAINTY OF MEASUREMENT FOR DENSITY DETERMINATION OF SOLIDS............ 22

9 USER INSTRUCTIONS................................................................................................................ 23

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1 Introduction

Safety instruct ions:

In order to guarantee a safe and smooth operation of this instrument, you have tocomply with the precautions below.

1. Carefully read the operating instructions.2. Handle this set and the balance with care as they are precision instruments.

This set contains parts made of glass. Protect all parts against shocks andimpacts.

3. Do not disassemble this set nor the balance.

KERN ABT-A01 Density determination set for analytical balances of theKERN ABT series(readability d = 0.1 mg).This set is designed for the efficient determination of the density of solids by meansof an analytical balance.In addition the density of fluids may be determined by means of an additionalplummet.

These operating instructions only describe the operation of the density determinationset. For further information on how to operate your balance please refer to theoperating instructions supplied with each balance.

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1.1 Scope of delivery

SAMPLE DISHSAMPLE DISH

FILTER BOWL FILTER BOWL

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MONTAGE THERMOMETER:

No. Designation

1 Platform assembly (sample dish and sifting bowl), 2 x

2 Weighing platform with rack

3 Beaker

4 Platform for glass beaker

5 Thermometer

6 Holder for thermometer

7 --

8 Glass plummet

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2 Install ing the density determination set1. Turn off and disconnect the power supply for the balance

2. Open the lateral glass doors of the weighing space of the balance and remove the

grading ring, the weighing plate and the support of the weighing plate.

3. Carefully insert the weighing platform with rack onto the floor of the weighingspace.

4. Place the platform for the glass beaker above it without touching the weighingplatform, as shown.

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5. Attach the platform assembly (sample dish and sifting bowl) to the rack of theweighing platform. In doing so, bear in mind that the centering of the upper sampledish matches the notch in the upper part of the weighing platform.

6. Close the glass doors and connect the power supply for the balance. Wait for the

auto test of the balance and the display message "oFF. Some models additionallycarry out an automatic adjustment before displaying oFF. (Connect the balance tothe platform assembly but without any fluid in the glass beaker. )

7. Turn on the balance by pressing the [ON/OFF] key, so that gram appears on thedisplay.

8. Attach the holder with thermometer to the glass beaker. Fill the glass beaker withknown fluid (for density determination of solids) or test fluid (for density determinationof fluids).

9. To be able to place the glass beaker in the centre of the platform, the platformassembly must first be removed from the rack.

10. Reattach the platform assembly to the rack and ensure that the sifting bowl doesnot touch the glass beaker.

11. Observe the waiting time until the test fluid, the known fluid, the instruments orthe plummet have the same temperature. For the balance also observe the requiredwarm-up time. (For details please refer to the operating instructions for the balance)

At tention:

The platform for the beaker must not touch the frame!

When the density set is installed, correct adjustment is not possible. Toachieve correct adjustment reinsert the weighing p late.

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3 Principle of Density Determination

Three physical magnitudes are the volume and the mass of bodies as well as thedensity of matter. In density mass and volume are related.

Density [ ] is the relation of mass [ m ] to volume [ V ].

= AA-B

o

=mV

SI-unit of density is kilogram divided by cubic meter (kg/m). 1 kg/m equals thedensity of a homogenous body that, for a mass of 1 kg, has the volume of 1 m.

Additional frequently applied units include:1

g

cm3

,1

kg

m3

,1

g

l

The application of this density determination set in combination with the KERN ABTbalance provides fast and safe determination of solids and fluids. Our set uses the"Principle of Archimedes" to determine density:

BUOYANCY IS A FORCE. IT AFFECTS A BODY THAT IS IMMERSED INTO A FLUID. THEBUOYANCY OF THE BODY EQUALS THE WEIGHT FORCE OF THE DISPLACED FLUID. THEFORCE OF BUOYANCY ACTS VERTICALLY UPWARDS.

Thus, density is calculated according to the formulae below:

Density determination of solids:

This balance enables weighing of solids in air [ A ] as well as water [ B ]. If the

density of the buoyancy medium is known [ o ] the density of the solid [ ] iscalculated as follows:

= density of sampleA = weight of the sample in airB = weight of sample in measuring fluid

o = density of measuring fluid

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Determining density of liquids:

The density of a fluid is determined with the help of a plummet providing a knownvolume [ V ]. The plummet is weighed in air [ A ] as well as in the sample fluid [ B ].

According to the Archimedes Principle a body immersed in a fluid experiences aforce of buoyancy [ G ]. This force equals the weight force of the fluid displaced bythe volume of the body.The volume [ V ] of the immersed body equals the volume of the displaced fluid.

=GV

G = buoyancy of plummet

Buoyancy of plummet =

Weight of the sinker in air [ A ] - weight sinker in sample liquid [ B ]

From this follows:

=

V

A-BL+

= density of sample fluidA = weight of plummet in airB = weight of plummet in sample fluidV = volume of plummet

L = air density (0.0012 g/cm)

3.1 Influencing magnitudes and error sources

Air pressure

Temperature

Volume deviance of the sinker ( 0.005 cm3)

Surface tension of the liquid

Air bubbles

Immersion depth of the sample dish of sinker

Porosity of the solid

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4 Density determination of solids

Prepare balance as described in chapter 2 "Installation of density determination set".

Install holder for the thermometer on beaker rim.

Suspend thermometer

Fill your measuring liquid, whose density o is known, into the beaker.Filling height should be approx. of the capacity.

Place beaker in the centre of the platform

Suspend sample dish from the centre of the frame

Heat measuring liquid until temperature is constant.

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4.1 Activate funct ion

Press several times the [UNIT] key to change the display between activated units,piece counting, percentage and density determination mode.This does not require additional software.

Settings have to be activated in the menu:

Repeatedly press the [CAL] key until "FUnC.SEL" appears.

Press [TARE] key

(Example)Repeatedly press the [CAL] key until "Unit.SEL" appears.

Press [TARE] key

Use the [CAL] key, to select the settings below:

U- ,d ( , this is an upside down triangle)Current settings are indicated by the standstill display ( ).

Confirm your selection by pressing the [TARE] key.

The [TARE] key is also used to deactivate a unit or function ifthe corresponding setting with standstill display is shown in thedisplay.

Repeatedly press the [ON/OFF] key. This takes you back to themenu/weighing mode.

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4.2 Entering Density for Fluid

Press the [CAL] key repeatedly until "SettinG" appears.

Press the [TARE] key.

Repeatedly actuate the [CAL] key until "LSG SEt" appears

(Example)

Press the [TARE] key. The currently set density for the liquid to be

measured appears. In the upper part of the display panel, thesymbol and the # symbol appear in order to indicatenumerical input status. The leftmost digit blinks.

(Example)

Enter density for the liquid to be measured. When the [UNIT] keyis pressed, the numerical of the blinking digit increases by 1 at atime. You can determine the value of the flashing digit, or shift theflashing digit by one position to the right, by pressing the [PRINT]key. Confirm your setting by pressing the [TARE] key.

Repeatedly press the [ON/OFF] key until the balance is inweighing mode.

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4.3 Carrying Out Measurement

Repeatedly press the [UNIT] key until the balance is in densitydetermination mode for solids ",d". Note that g also appearsduring weight measurement in air.

Press the [TARE] key. Place the object to be measured on thesample dish.

When standstill control is complete, press the [CAL] key.

Place the item to be measured on the immersed sifting bowl. Thedisplay is showing the density of the measured item. dSP oL maybe displayed when nothing is on the weighing pan, which isnormal.

To start next measurement, press the [CAL] and the [ TARE ] keyand place the object to be measured on the weighing tray.

5 Determining density of liquids

Prepare balance as described in chapter 2 "Installation of density determination set".

Install holder for the thermometer on beaker rim.

Suspend thermometer

Fill your measuring liquid into the beaker. Filling height should be approx. of thecapacity.

Heat measuring liquid until temperature is constant.

Prepare glass sinker

5.1 Activate funct ion

Press several times the [UNIT] key to change the display between activated units,piece counting, percentage and density determination mode.This does not require additional software.

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Settings have to be activated in the menu:

Repeatedly press the [CAL] key until "FUnC.SEL" appears.

Press [TARE] key

(Example)Repeatedly press the [CAL] key until "Unit.SEL" appears.

Press [TARE] key

Use the [CAL] key, to select the settings below:

U- d

Current settings are indicated by the standstill display ( ).

Confirm your selection by pressing the [TARE] key.

The [TARE] key is also used to deactivate a unit or function ifthe corresponding setting with standstill display is shown in thedisplay.

Repeatedly press the [ON/OFF] key. This takes you back to themenu/weighing mode.

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5.2 Entering Density of Glass Plummet

Press the [CAL] key repeatedly until "SettinG" appears.

Press the [TARE] key.

Repeatedly actuate the [CAL] key until "Sv SEt" appears

(Example)

Press the [TARE] key. The currently set density for the body to beimmersed appears. In the upper part of the display panel, the

symbol and the # symbol appear in order to indicatenumerical input status. The leftmost digit blinks.

(Example)

Enter density for your body to be immersed. When the [UNIT] keyis pressed, the numerical of the blinking digit increases by 1 at atime. You can determine the value of the flashing digit, or shift theflashing digit by one position to the right, by pressing the [PRINT]key. Confirm your setting by pressing the [TARE] key.

Repeatedly press the [ON/OFF] key until the balance is in

weighing mode.

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5.3 Carrying Out Measurement

Remove the platform assembly and the glass beaker from the platform.

Repeatedly press the [UNIT] key until the balance is in densitydetermination mode for liquids "d". Note that g also appearsduring weight measurement in air.

Press the [TARE] key. To carry out a measurement in air, attachthe glass plummet to the rack.

When standstill control is complete, press the [CAL] key

Remove the glass plummet.

Place the glass beaker containing the test fluid on the platform forthe glass beaker.

Reattach the glass plummet to the rack and immerse it completelyin the fluid without producing bubbles.

The display is showing the density of the sample. If no glassplummets are available the message dSP oL might appear whichis normal.

To start the next measurement, press the [CAL] key and [TARE] key and reattachthe glass plummet to the rack without the glass beaker, in order to carry out ameasurement in air.

Ensure that the glass beaker is dry and clean each time you fill it with test fluid.The same applies to the glass plummet.

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6 Preconditions for Precise Measurements

There are numerous error possibilities during density determination.Accurate knowledge and caution are required to achieve precise results whenapplying this density set in combination with the balance.

6.1 Calculation of Results

The balance displays results for density determination by giving four decimal places.However, this does not mean that the results are accurate down to the last decimalplace as this would be the case for a calculated value. Therefore all weighing resultsused for calculations have to be examined closely.

Example for density determination of solids:To ensure high-grade results, numerators as well as common denominators of theformula below must show the desired accuracy. If either of them is instable or flawed,the result, too, will be instable or flawed.

=A

A-Bo

= density of sampleA = weight of the sample in airB = weight of sample in measuring fluid

o = density of measuring fluid

The use of a heavy specimen contributes to the accuracy of a result because thisincreases the numerical value. The use of a light-weight specimen, too, contributes tothe accuracy of a result because this increases buoyancy (A-B). As a consequence,

the result of the common denominator increases. Bear also in mind that the accuracyof the density of the measuring fluid o enters into the common denominator and,thus, has considerable influence on the accuracy of the result.The result for the density of the specimen cannot be more accurate than the leastaccurate of the aforementioned individual entities.This fact applies equally to the determination of density for fluids and glass plummetadjustment.

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6.2 Influence Factors for Measurement Errors

6.2.1 Air bubblesA small bubble of, for example, 1mm

3will have a considerable influence on the

measurement if the specimen is small. Buoyancy will be increased by approximately1mg resulting immediately in an error of 2 digits. Hence, it has to be ensured that noair bubbles cling to the solid immersed in the fluid. The same applies to the glassplummet that is immersed in the test fluid.Take great care when removing air bubbles by swirling, to prevent the fluid fromspurting out and splashing onto the sifting bowl. Moisture on the suspension bracketof the sifting bowl results in increased weight.Do not touch the solid sample or glass plummet with bare fingers. An oily surfacecauses air bubbles when immersing the specimen in fluids.Do not place solid specimens (in particular flat objects) in the sifting bowls as thiswould result in air bubbles when immersed together. For this reason examine thebottom of the sifting bowl for air bubbles after the specimen had been immersed influid.

6.2.2 Solid Specimen

A specimen possessing too great a volume that is immersed in fluid will result in anincrease in fluid level inside the glass beaker. As a result, part of the suspensionbracket of the sifting bowl will also be immersed causing buoyancy to increase. As a

consequence the weight of the specimen in the fluid will drop.Specimens that change the volume or assimilate fluid are unsuitable formeasurement.

6.2.3 Liquids

Water temperature is another factor to be taken into consideration. The density ofwater changes by c. 0.01% per degree Celsius. A temperature measurementshowing an error of 1 degree Celsius results in an inaccurate fourth decimal place.If the specimen absorbs the fluid or dissolves during the measurement in the fluid, adifferent fluid should be chosen. Additionally take into consideration that the fluid

might evaporate.

6.2.4 Surface

The suspension bracket of the sifting bowl penetrates the surface of the fluid. Thisstate undergoes continuous change. If the specimen or the glass plummet isrelatively small, the surface tension will impair repeatability. The addition of a smallamount of detergent makes the surface tension negligible and increasesrepeatability.

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6.2.5 Glass Plummet for Measuring Fluids

To save test fluids used for density determination of fluids, use a small glass beakerand an accordingly sized glass plummet. However, it needs to be pointed that a largeglass plummet achieves higher accuracy.It is desirable that the buoyancy and the volume of the glass plummet are determined

as accurately as possible. For the determination of fluid density these results areapplied to the common denominator as well as the numerator of the formula.

6.3 General information

6.3.1 Density / Relative Density

Relative density follows from the weight of a specimen divided by the weight of water(at 4 Celsius) of the same volume. For this reason relative density does not have aunit. Density equals mass divided by volume.The application of the relative density instead of the density of a fluid in a formulaproduces an incorrect result. In the case of fluids only their density isphysically meaningful.

6.3.2 Drift of Balance Display

The drifting of a balance does not influence the final result of the density

determination although the shown weight of weighing in air is affected. Accuratevalues are merely required if the density of fluids is determined by means of a glassplummet.For this purpose some of the models carry out auto-adjustment.

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7 Density Table for Fluids

Density p [g/cm3]Temperature

[C] Water Ethyl alcohol Methyl alcohol

10 0.9997 0.7978 0.8009

11 0.9996 0.7969 0.8000

12 0.9995 0.7961 0.7991

13 0.9994 0.7953 0.7982

14 0.9993 0.7944 0.7972

15 0.9991 0.7935 0.796316 0.9990 0.7927 0.7954

17 0.9988 0.7918 0.7945

18 0.9986 0.7909 0.7935

19 0.9984 0.7901 0.7926

20 0.9982 0.7893 0.7917

21 0.9980 0.7884 0.7907

22 0.9978 0.7876 0.7898

23 0.9976 0.7867 0.7880

24 0.9973 0.7859 0.7870

25 0.9971 0.7851 0.7870

26 0.9968 0.7842 0.7861

27 0.9965 0.7833 0.7852

28 0.9963 0.7824 0.7842

29 0.9960 0.7816 0.7833

30 0.9957 0.7808 0.7824

31 0.9954 0.7800 0.7814

32 0.9951 0.7791 0.7805

33 0.9947 0.7783 0.7896

34 0.9944 0.7774 0.788635 0.9941 0.7766 0.7877

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8 Uncertainty of Measurement for DensityDetermination of Solids

This table shows the approximate readability of the balance in connection with thedensity set. In doing so take into consideration that these theoretically calculatedvalues may vary according to ambient conditions.In addition observe chapter 6.

Example to table below:

Test of a solid weight of 5 gram and a density of 3 g/cm3.The minimum display value for density is 0.0004 g/cm

3. Thus the last display digit of

the display (readability of 0.0001) is not relevant for this measurement.

Approximative readability at the density determination(when using the 0.1mg range)

Weight (g) of thespecimen

1 5 10 100 200 300

1 0.001 0.0001 0.0001 0.0001 0.0001 0.0001

3 0.002 0.0004

Density ofthe specimen(g/cm

3)

0.0003 0.0001 0.0001 0.0001

5 0.003 0.001 0.0004 0.0002 0.0002 0.0002

8 0.004 0.001 0.0006 0.0003 0.0003 0.0003

10 0.005 0.001 0.0008 0.0004 0.0003 0.0003

12 0.006 0.002 0.001 0.0004 0.0004 0.0004

20 0.01 0.003 0.002 0.001 0.001 0.001

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9 User Instructions To form a reproducible mean value several density measurement are necessary

Remove fat from solvent-resistant sample / /glass sinker /beaker.

Regularly clean sample dishes/glass sinker/beaker, do not touch immersed partwith your hands

Dry sample/glass sinker/pincers after each measurement.

Adjust sample size to sample dish (ideal sample size > 5 g).

Only use distilled water.

When immersing for the first time, lightly shake sample dishes and sinker, in orderto Dissolve air bubbles.

Always ensure that, when re-immersing into the liquid no additional bubbles

adhere; it is better to use pincers to place the sample.

Remove firmly adherent air bubbles with a fine brush or a similar tool.

To avoid adherent air bubbles smoothen samples with rough surface.

Take care that no water drips onto the upper sample dish when weighing with thehelp of tweezers.

In order to reduce the surface tension of water and the friction of the liquid on thewire, add three drops of a common detergent (washing-up liquid) to themeasuring liquid (density modification of dest. water occurring due to the additionof tensides can be ignored).

Oval samples can be held more easily with pincers when you cut grooves intothem.

The density of porous solids may only be determined approximately. Buoyancyerrors occur when not all the air is eliminated from the pores during immersion inthe measuring fluid.

To avoid great vibrations of the balance, place sample carefully.

Avoid static charge, e. g. dry glass plummet with cotton cloth only.

If the density of your solid only deviates slightly from that of distilled water,ethanol may be used as measuring fluid. However, check beforehand whether thesample is solvent-proof. In addition you must observe the applicable safetyregulations when working with ethanol.

Handle glass sinker with care(no warranty claims in case of damage).