KERN PBS-A03 User manual

KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
email: [e-mail]
Phone: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
Operating instructions
Density Determination Set
KERN PBS-A03/A04
Version 1.4
07/2016
GB
PBS-A03/A04-BA-e-1614

2 PBS-A03/A04-BA-e-1614
GB
KERN PBS-A03/A04
Version 1.407/2016
Operating instructions
Set for density determination for precision balances
KERN PBJ/PBS
Contents:
1INTRODUCTION ............................................................................................................................ 3
1.1 SCOPE OF SUPPLY.................................................................................................................... 3
1.2 DIMENSIONS............................................................................................................................. 5
2INSTALLING THE DENSITY DETERMINATION SET.................................................................. 6
3PRINCIPLE OF DENSITY DETERMINATION............................................................................... 8
3.1 INFLUENCING MAGNITUDES AND ERROR SOURCES...................................................................... 9
4DENSITY DETERMINATION OF SOLIDS................................................................................... 10
+ACCESS MODE FOR THE DENSITY DETERMINATION OF SOLIDS........................................................ 10
+INPUT „DENSITY AUXILIARY FLUID“ ............................................................................................... 12
+ACCESS MODE FOR THE DENSITY DETERMINATION OF SOLIDS........................................................ 14
5DETERMINING DENSITY OF LIQUIDS ...................................................................................... 17
5.1 VOLUME DETERMINATION OF THE SINKER................................................................................. 17
5.2 DENSITY DETERMINATION AT KNOWN VOLUME OF THE SINKER................................................... 19
+MODE TO CALL UP DENSITY DETERMINATION OF LIQUIDS ............................................................... 19
+ENTER SINKER VOLUME............................................................................................................... 21
+DENSITY DETERMINATION OF THE TEST FLUID............................................................................... 23
6PRECONDITIONS FOR PRECISE MEASUREMENTS............................................................... 26
6.1 CALCULATION OF RESULTS..................................................................................................... 26
6.2 INFLUENCE FACTORS FOR MEASUREMENT ERRORS ................................................................. 27
6.2.1 Air bubbles....................................................................................................................... 27
6.2.2 Solid body sample ........................................................................................................... 27
6.2.3 Liquids.............................................................................................................................. 27
6.2.4 Surface............................................................................................................................. 27
6.3 GENERAL INFORMATION.......................................................................................................... 27
6.3.1 Density / Relative Density................................................................................................ 27
7DENSITY TABLE FOR FLUIDS................................................................................................... 28
8USER INSTRUCTIONS................................................................................................................ 29

PBS-A03/A04-BA-e-1614 3
1 Introduction
KERN PBS-A03 KERN PBS-A04
•Set for density determination for
precision balances of the series
KERN PBJ/PBS with big weighing
plate (180 x 170 mm).
•Set for density determination for
precision balances of the series
KERN PBJ/PBS with small
weighing plate (105 x 105 mm).
•When using the density set, the
capacity of the balance is reduces
by approx. 100 g.
•When using the density set, the
capacity of the balance is reduces
by approx. 290 g.
•In order to guarantee a safe and trouble-free operation, please
read carefully the operating instructions.
•These operating instructions only describe the operation of the
density determination set. For further information on how to
operate your balance please refer to the operating instructions
supplied with each balance.
1.1 Scope of supply
Fig. 1: Installed density set KERN PBS-A04

4 PBS-A03/A04-BA-e-1614
1. Weighing tray holder
2. Combination weighing tray
3. Container table
4. Container
5. Weighing tray carrier,
4 items
6. Glass sinker

PBS-A03/A04-BA-e-1614 5
1.2 Dimensions

6 PBS-A03/A04-BA-e-1614
2 Installing the density determination set
•If necessary, carry out necessary adjustment before installation of the density
set.
•When the density set is installed, correct adjustment is not possible.
•For reasons of adjustment, take away the density set and place the standard
weighing plate.
•The following pictures show the density set KERN PBS-A03 at a balance with
big weighing plate. The density set KERN PBS-A04 must be installed at the
same way.
1. Switch off balance and separate it from the power supply.
2. Remove standard weighing plate.
3. Remove carrier of the standard
weighing plate and replace by
weighing tray carrier of the density
set.
4. Put balance tray holder according to
fig. into the four balance tray carriers.
Thereby observe the right position,
the openings on the upper side must
point forwards.

PBS-A03/A04-BA-e-1614 7
A
B
5. Place the container table in a way
that it does not touch the balance tray
holder.
6. Put the containers in the center of the
container table
7. Hook up the combination balance
tray according to illustration; ensure
that it does not touch the container.

8 PBS-A03/A04-BA-e-1614
ρ =
A
A-B o
ρ
ρ =
m
V
3 Principle of Density Determination
Three physical magnitudes are the volume and the mass of bodies as well as the
density of matter. In density mass and volume are related.
Density [ ρ] 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.
Additional frequently applied units include:
, ,
The application of this density determination set in combination with the KERN PBS/PBJ
balances 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. THE BUOYANCY
OF THE BODY EQUALS THE WEIGHT FORCE OF THE DISPLACED FLUID. THE FORCE OF
BUOYANCY ACTS VERTICALLY UPWARDS.
Thus, density is calculated according to the formulae below:
Determining density of solid bodies
Our balances enable weighing of solids in air [ A ] as well as 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 sample
A = weight of the sample in air
B = weight of sample in measuring fluid
ρo = density of measuring fluid
1g
cm3
1kg
m3
1g
l

PBS-A03/A04-BA-e-1614 9
ρ = V
A-B
L
ρ
+
Determining density of liquids
The density of a fluid is determined with the help of a sinker providing a known volume [ V
]. The sinker is weighed in air [ A ] as well as in the test fluid [ B ].
According to the Archimedes’ Principle a body immersed in a fluid experiences a force of
buoyancy. [ G ]. This force equals the weight force of the fluid displaced by the volume of
the body.
The volume [ V ] of the immersed body equals the volume of the displaced fluid.
G = buoyancy of sinker
Buoyancy of sinker =
Weight of the sinker in air [ A ] -weight sinker in test liquid [ B ]
From this follows:
ρ= Density of test liquid
A = weight of sinker in air
B = weight of sinker in sample fluid
V = volume of sinker*
ρL = Air density (0.0012 g/cm³)
* If the volume of the sinker is unknown, this can be determined e.g. in water and be
calculated as follows, see chap. 5.1.
V = volume of sinker
A = weight of sinker in air
B = weight of sinker in water
ρW = density of water
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

10 PBS-A03/A04-BA-e-1614
4 Density determination of solids
For the determination of the density of solids, the solid is first weighed in air and then
in the aid liquid, whose density is known. From the weight difference results the
buoyancy from where the software calculates the density.
As aid liquid, usually distilled water or ethanol is used, see density tables chapter 7.
Prepare balance as described in chapter 2 "Installation of density determination
set".
Fill auxiliary fluid into the container. Filling height should be approx. ¾ of the
capacity. Bring liquid and instruments to the right temperature until you achieve a
constant temperature. Observe the warm-up time of the balance.
+Access mode for the density determination of solids.
Switch on balance
In weighing mode press repeatedly until „U“ flashes.
MENU
CAL

PBS-A03/A04-BA-e-1614 11
Press .
Press repeatedly until „U-

d“ is displayed.
From now on the balance is in density determining mode for solids.
Press , the current setting of „SG HOLD“ will be displayed.
Press to select the desired setting for the display mode.
Every time is pressed the symbol ( ) is unhidden or hidden.
() on: Hold display mode (the displayed density value will be kept on display).
() off: Continuous display mode (the displayed density value will be
continuously updated according to the weight change in the auxiliary fluid).
TARE /
MENU
CAL
TARE /
TARE /
TARE /

12 PBS-A03/A04-BA-e-1614
+Input „Density auxiliary fluid“
Press , the density of the auxiliary fluid saved as last will be displayed, at
the first input, the value will be zero. The active digit is flashing.
When changing by the arrow keys, enter first the numeric value of the density
considering the current temperature (see chap. 7), then set the decimal place.
Use to increase the numeric value of the flashing cipher.
Use to move the cipher selection to the right, the respective active
position flashes.
Input example for the value „1.000“:
Press repeatedly until the forth digit flashes.
Press to set the numeric value „1“.
To set the decimal place , take the last place using , when this place
dot is flashing, press anew. The symbol pops up.
MENU
CAL
UNIT
PRINT
PRINT
UNIT
PRINT
PRINT

PBS-A03/A04-BA-e-1614 13
Use to define the position of the decimal place.
Confirm input by .
Observe that the stability mark is displayed, if not, the entry has not been
accepted.
Press repeatedly or keep pressed for 3 sec until the gram display will
appear.
UNIT
TARE /
ESC
ON/OFF

14 PBS-A03/A04-BA-e-1614
+Access mode for the density determination of solids.
1. In weighing mode press repeatedly until [Air g d] will be displayed. After
approx. 2 sec the display changes automatically into the density determination
mode for solids.

Reset to zero if necessary by pressing .
2. Place sample in the upper sample dish.
3. The weight of the „sample in air“ is displayed. When an optional printer is
connected, the displayed value can be edited using .
Wait for stability display (), then press .
UNIT
TARE /
PRINT
MENU
CAL

PBS-A03/A04-BA-e-1614 15
4. For approx. 2 s “wAtr” will be displayed. The display changes automatically to
[0.00 g d ] Remove sample from the upper sample dish and set to zero if
necessary.

5. Remove sample from the upper sample dish. Reset to zero if necessary by pressing
.
6. Lay the sample into the lower sample dish and immerse it in the auxiliary liquid.
Make sure that the sample is at least 1 cm immersed and has, if possible, no air
bubbles adhering to it.
7.
The weight of the „sample in auxiliary liquid“ is displayed. When an optional printer is
connected, the displayed value can be edited using .
8. Wait for stability display (), then press .
The scale determines the density of the sample and then displays the result.
When „Hold display mode“ is enabled, the symbol [ ] will be unhidden.
TARE /
PRINT
MENU
CAL

16 PBS-A03/A04-BA-e-1614
9. When connecting an optional printer, the result will be printed after pressing
.
Printout example:
If necessary, remove the decimal place by pressing the UNIT-button as follows:
Four decimal places (1d)
Three decimal places (10 d)
Two decimal places (100 d)
One decimal place (1000 d)
To start the next measurement press , before the current sample is
removed from the lower sample dish.
For the new measurement start at step 2.
Using the balance returns into the weighing mode.
To avoid damage by corrosion, don't leave the immersion basket set immersed in
liquid for a longer time.
PRINT
MENU
CAL
UNIT
Keep pressed the UNIT-button 3 seconds
Keep pressed the UNIT-button 3 seconds
Keep pressed the UNIT-button 3 seconds
Keep pressed the UNIT-button 3 seconds
3.4999DS

PBS-A03/A04-BA-e-1614 17
5 Determining density of liquids
For density determination of liquids, a plummet is used, whose volume is known. The
sinker is weighed first in air and then in the liquid whose density is to be determined.
From the weight difference results the buoyancy from where the software calculates
the density.
The volume of the added glass sinker will be computed as described in the following
chapter 2.1.
5.1 Volume determination of the sinker
Prepare balance as described in chapter 2 "Installation of density determination
set".
Dest. Fill water into the container. Filling height should be approx. ¾ of the
capacity. Heat sample liquid until temperature is constant.
Keep the sinker ready

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1. Switch-on balance, repeatedly press the key until the balance is in
weighing mode.
2. Place sinker in the upper sample dish. Wait for stability display to appear; write
down the displayed weighing value.
3. Place sinker in the lower sample dish. Wait for stability display to appear; write
down the displayed weighing value.
The volume of the sinker is computed by applying the following formula.
V = volume of sinker
A = weight of the sinker in air = 99.998 g
B = weight of the sinker in water = 87.607 g
ρW = density of water (see chap. 7) at 20°C = 0.9982 g/cm³
UNIT

PBS-A03/A04-BA-e-1614 19
5.2 Density determination at known volume of the sinker
Prepare the balance as described in chapter 2„Installing density determination
set“ (step 1-6).
Keep the sinker ready
Fill test liquid in the container. Filling height should be approx. ¾ of the capacity.
Control the temperature of the liquid, instruments and the displacement body until
the temperature is constant. Observe the warm-up time of the balance.
+Mode to call up density determination of liquids
Switch on balance
In weighing mode press repeatedly until „U“ flashes.
MENU
CAL

20 PBS-A03/A04-BA-e-1614
Press .
Press repeatedly until [U-d] is displayed.
From now on the balance is in density determining mode for liquids.
Press , the current setting of „SG HOLD“ will be displayed.
Press to select the desired setting for the display mode.
Every time is pressed the symbol ( ) is unhidden or hidden.
() on: Hold display mode (the displayed density value will be kept on display).
() off: Continuous display mode (the displayed density value will be
continuously updated according to the weight change in the auxiliary fluid).
TARE /
MENU
CAL
TARE /
TARE /
TARE /