KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: info@kern-sohn.com
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
Operating instruction
Set for density determination
KERN ALS/PLS-A01
Version 1.5
04/2008
E
ALS/PLS-A01-BA-e-0815
GB
KERN ALS/PLS-A01
Version 1.5 04/2008
Operating instruction
Set for density determination for precision and analytical
balances KERN ALT, KERN PLT, KERN ALS/ALJ, KERN
ALS..N/ALJ..N, KERN PLS/PLJ
Contents:
1 INTRODUCTION ............................................................................................................................ 4
1.1 SCOPE OF DELIVERY................................................................................................................. 4
2 INSTALLATION OF DENSITY DETERMINATION SET................................................................6
3 PRINCIPLE OF DENSITY DETERMINATION............................................................................. 10
3.1 INFLUENCING MAGNITUDES AND ERROR SOURCES .................................................................... 11
4 DENSITY DETERMINATION OF SOLIDS................................................................................... 12
4.1 MODELS KERN ALS/ALJ/PLS/PLJ........................................................................................ 13
4.2 MODELS ALJ..N/ALS..N ........................................................................................................ 18
4.3 MODELS KERN ALT, PLT...................................................................................................... 21
5 DENSITY DETERMINATION OF LIQUIDS ................................................................................. 27
5.1 MODELS KERN ALS/ALJ/PLS/PLJ........................................................................................ 29
5.2 MODELS KERN ALJ..N/ALS..N.............................................................................................. 33
5.3 MODEL KERN ALT, PLT........................................................................................................ 36
6 DENSITY TABLE FOR WATER .................................................................................................. 41
7 RECOMMENDATIONS................................................................................................................42
ALS/PLS-A01-BA-e-0815 3
1 Introduction
When acquiring a density set as accessory for your electronic balance there are
2 models available:
KERN ALS-A01 for analysing balances of the KERN ALT, KERN ALS/ALJ and
KERN ALS..N/ALJ..N series (only suitable for models with
readability d = 0.1 mg).
KERN PLS-A01 for analysing balances of the KERN PLS/PLJ and KERN PLT
series (only suitable for models with readability d = 1 mg).
This manual only descries working with the density determination set. For further
information concerning operation of your balance please refer to the operating
manual of the respective balance.
1.1 Scope of delivery
KERN ALS-A01:
No. Denomination
1 Platform for beaker 9 Sample dish
2 Frame 10 Wire
3 Glass sinker 11 Sieve dish
4 Beaker 12 Additional weights (see chap. 5)
5 Holder for thermometer 13 Additional frame (Storage for sample
dishes/sinker)
6 Thermometer Pincers w/o picture
7 Wire Operating instruction
8 Hook for sinker
4 ALS/PLS-A01-BA-e-0815
KERN PLS-A01
No. Denomination
1 Frame 7 Thermometer
2 Sieve dish 8 Holder for thermometer
3 Wire 9 Glass sinker
4 Sample dish 10 Platform for beaker
5 Beaker 11 Additional frame (Storage for
sample dishes/sinker)
6 Hook for sinker Pincers w/o picture
Operating instruction
ALS/PLS-A01-BA-e-0815 5
2 Installation of density determination set
Ö Remove the following parts from the balance
Model KERN ALT:
Model KERN ALS/ALJ:
1
2
3
(1) Weighing plate
(2) Screening ring
(1) Weighing plate
(2) Support for weighing plate
(3) Screening ring
6 ALS/PLS-A01-BA-e-0815
Model KERN PLS/PLJ, PLT:
Ö Installation of density determination set
Models KERN ALS/ALJ, KERN ALT: Central 1-point receptacle
(1) Windshield cover
(2) Windshield
(3) Weighing plate
ALS/PLS-A01-BA-e-0815 7
Models KERN ALS..N/ALJ..N,: Central 1-point receptacle
8 ALS/PLS-A01-BA-e-0815
Models KERN PLS/PLJ, PLT: 4-point receptacle
Attention:
• The platform for the beaker must not touch the frame!
• When the density set is installed, adjustment is not possible.
For adjustment, re-install weighing plate.
ALS/PLS-A01-BA-e-0815 9
3 Principle of density determination
g
g
g
A
A-B
Three physical magnitudes are the volume and the mass of bodies as well as the
density of matter. Mass and volume are connected with each other in density:
Density [ ( ] is the relation of mass [ m ] to volume [ V ].
SI-unit of density is kilogram divided by cubic meter (kg/m³). 1 kg/m³ equals the
density of a homogenous body that, for a mass of 1 kg, has the volume of 1 m³.
Other frequently used units are:
Using our set for density determination in combination with our balances KERN
ALS/ALJ/PLS/PLJ, KERN PLT and KERN ALT enables you to determine the density
of solids and liquids fast and correctly. Our set uses the "Principle of Archimedes"
to determine density:
Buoyancy is a force. It affects a body that is immersed in a liquid. A
body’s buoyancy is as large as the weight of the liquid it displaces.
Buoyancy is effective vertically upwards.
Thus, density is calculated according to the following formulas:
For density determination of solids
Our balances enable you to weigh solids in air [ A ] as well as in water [ B ]. If the
density of the buoyancy medium is known [ ρo ] the density of the solid [ ρ ] is
calculated as follows:
ρ = Density of the sample
A = Weight of the sample in air
B = Weight of the sample in measuring liquid
ρo = Density of the measuring liquid
ρ =
ρ =
m
V
,
k
1
m
1
3
,
l
1
ρ
3
cm
o
10 ALS/PLS-A01-BA-e-0815
For density determination of liquids
G
A-B
The density of a liquid is determined by using a sinker, whose volume ([ V ] is known
see embossment). The sinker is weighed in air [ A ], as well as in sample liquid [ B ].
According to the law of Archimedes, a body that immersed in a liquid is exposed to
buoyancy [ G ]. The absolute value of this force equals the weight of the liquid
displace by the volume of the body.
The volume [ V ] of the immersed body equals the volume of the displaced liquid.
ρ =
ρ =
V
V
+
ρ
L
G = Buoyancy of the sinker
Buoyancy of the sinker =
Weight of the sinker in air [ A ] - weight sinker in sample liquid [ B ]
Thus follows:
ρ = Density of sample liquid
A = Weight of sinker in air
B = Weight of sinker in sample liquid
V = Volume of the sinker
= Air density (0.0012 g/cm³)
ρ
L
3.1 Influencing magnitudes and error sources
Ö Air pressure
Ö Temperature
Ö Volume deviance of the sinker (± 0,005 cm
Ö Surface tension of the liquid
Ö Air bubbles
Ö Immersion depth of the sample dish of sinker
Ö Porosity of the solid
ALS/PLS-A01-BA-e-0815 11
3
)
4 Density determination of solids
Prepare balance as in chapter 2 "Installation of density determination set".
Ö Install holder for the thermometer on beaker rim.
Ö Suspend thermometer
Ö Fill your measuring liquid, whose density ρo is known, into the beaker. Filling
height should be approx. ¾ of the capacity.
Ö Place beaker in the centre of the platform
Ö Suspend sample dishes from the centre of the frame
Ö Heat measuring liquid until temperature is constant.
12 ALS/PLS-A01-BA-e-0815
4.1 Models KERN ALS/ALJ/PLS/PLJ
Key Display Description
or
Turn on balance; balance will
carry out self-check.
Wait until the stability and
balance zero-display shows
Menu selection:
Press TARE -key; the display
shows horizontal lines; while this
display is shown, press the
F -key. The first function “Add“
or “Pieces” appears.
Keep the F –key pressed until
the density function for solids
ALS/PLS-A01-BA-e-0815 13
"Co" is displayed.
Confirm your selection.
The balance is now in density
determination mode for solids.
O
O
O
Select measuring liquid:
If you selected distilled water or ethanol as measuring liquid, enter the temperature
of the measuring liquid in the next menu step.
TE-L 0
Use the F -button to choose
between the following settings:
H20 = Distilled water
C2H5OH = Ethanol
nother = Measuring liquid
of your choice,
whose density is
known
Confirm your selection.
Read the temperature of the
measuring liquid from the
suspended thermometer and
then enter it as follows (current
number is blinking).
Use the F – key to change the
TE-L 2
TE-L 2
value of the number
Use the ON/OFF – key to select
the place you want to change,
the currently active place is
blinking
Confirm your entry.
14 ALS/PLS-A01-BA-e-0815
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