UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
Valid for:
2 years from
approval
Table of Contents
Page
1.
2.
3.
4.
5.
6.
7.
8.
9.
Scope
Objective
Definitions
Responsibility
Procedure
5.1. Diagram of KERN® 120-4NM Electronic Precision Balance
5.2. Installation
5.3. Configuration
5.4. Operation
5.5. Calibration
5.6. Maintenance
5.7. Troubleshooting
5.8. Flow charts
Precautions
References
Appendices
Revision History
Page 1 of 13
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5
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12
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12
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
Valid for:
2 years from
approval
1. Scope
This Standard Operating Procedure (SOP) applies to the staff and students
making use of the KERN® 120-4NM Precision Balance in the laboratories of
the Pharmacy Department, University of Malta.
2. Objective
To describe the procedure for the installation, configuration, operation,
calibration, maintenance and troubleshooting of the KERN® EW 120-4NM
Precision Balance.
3. Definitions
3.1.
Calibration: A procedure performed to check a measuring instrument
against an accurate standard to determine any deviations and correct for
errors.
3.2.
Configuration Parameters: A number of different options that are
used to set the balance according to the user’s preferences (see
SOP/PD/310_02/A1).
3.3.
F Key: To choose the desired function within the configuration
parameters.
3.4.
Foot Screws: Circular screws situated at the bottom of the balance that
are manipulated to level the balance out.
3.5.
On/Off Key: To switch the balance on or off.
3.6.
Print Key: To print weight value when balance is connected to an
external printing device.
3.7.
S Key: To save the chosen function in an individual configuration
parameter during balance configuration.
3.8.
Tare: Allows the balance to display the weight of the sample only and
not the combined weight of the sample and its container.
Page 2 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
3.9.
Valid for:
2 years from
approval
TARE Key: Used to tare the weight of the container during weighing
and also to change the function in an individual configuration
parameter.
3.10. Weighing Pan: The area on top of which the material to be weighed is
placed.
3.11. Weighing Range: Bar graph divided into 20 graphic cuboids with
none being displayed when there is no weighing value, 10 displayed
when balance is loaded up to one half of its weighing range and all 20
cuboids and F are displayed when balance is loaded to full capacity.
4. Responsibility
4.1.
The members of the Department of Pharmacy (staff and students) are
responsible for following this SOP.
4.2.
The designated Laboratory Officer or Laboratory Assistant is
responsible for ensuring that this SOP is followed.
5. Procedure
5.1.
Diagram of KERN® 120-4NM Electronic Precision Balance
Draft Shield
Weighing Pan
Spirit Level
Display
Keyboard
Foot Screw
Page 3 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.2.
Valid for:
2 years from
approval
Installation
5.2.1.
Place balance on a firm level surface, away from any
vibrations.
5.2.2. Manipulate the foot screws at the bottom of the balance until
the air bubble in the spirit level is in the displayed circle.
5.2.3. Attach the mains adaptor to the balance and then to the mains
supply if using the electrical supply to power the balance.
5.2.4. Insert suitable rechargeable batteries to power the balance if an
electrical supply is not available.
5.2.5. Switch on the balance from its main supply.
5.2.6. Ensure that [*] is displayed to indicate that balance is being
supplied with power via the mains adaptor.
5.2.7. Press the On/Off Key to switch on balance.
5.2.8. Allow the balance to warm up for about 10 minutes.
5.2.9. Ensure that a [0] stability sign appears on the display to indicate
that balance is in a stable condition. Ensure that all draft shields
are closed if [0] does not appear.
5.2.10. Wait until balance displays [0.000] to start using it.
5.2.11. Press the TARE Key to reset the balance to zero when [0.000] is
not being displayed inspite of having an empty weighing pan.
5.3.
Configuration
5.3.1.
5.3.2.
5.3.3.
5.3.4.
5.4.
Press the F key for about 4 seconds until [FUNC] appears.
Press the F Key repeatedly until the desired configuration
parameter is displayed (see SOP/PD/310_02/A1).
Press the TARE Key repeatedly until the desired number, which
corresponds with the desired function, is displayed.
Press the S Key to save the chosen function and return balance
to weighing mode.
Operation
5.4.1.
5.4.2.
5.4.3.
Ensure that the desired weighing unit is displayed. If this is not
so, use the configuration parameters menu to change it.
Place sample onto the weighing pan, close all draft shields and
read off value from the LCD display.
If using the tare function, place empty weighing container on
the weighing pan, press the TARE key and then place the
sample in the weighing container
Page 4 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.4.4.
5.4.5.
5.5.
Close all draft shields and read off the tared value from the
display.
Use the tare function repeatedly if necessary.
Calibration
5.5.1.
5.5.2.
5.5.3.
5.5.4.
5.5.5.
5.5.6.
5.5.7.
5.5.8.
5.6.
Valid for:
2 years from
approval
Choose an appropriate calibration weight.
Press and hold the F Key until [CAL] is displayed.
Press the F Key while holding down the TARE Key and then
subsequently release both keys simultaneously.
Place the desired calibration weight on the weighing pan.
Wait until the value of the calibration weight is displayed to
remove the weight from the weighing pan.
Repeat the calibration procedure if [-Err] is displayed due to a
calibration error or the use of a wrong calibration weight.
Wait until balance automatically returns to weighing mode
before further use.
Repeat calibration process with a different calibration weight if
necessary.
Maintenance
5.6.1.
5.6.2.
5.6.3.
5.6.4.
Disconnect the balance from the mains supply before
attempting any cleaning procedures.
Use a clean fine brush to remove fine particles and powders.
Use a moistened cloth with a mild cleaning agent for any spilt
material.
Ensure that the air bubble in the spirit level is in the centre of
the displayed circle.
Page 5 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.7.
Valid for:
2 years from
approval
Troubleshooting
Fault
Weight display not illuminated
-
Weight display changes continually
-
Weight result seemingly incorrect
5.7.1.
5.7.2.
-
Possible Cause/s
Balance not switched on
Mains supply cable not properly
plugged or is faulty
Interruption in power supply
Draught / air movements
Table / floor vibrations
Weighing pan in contact with foreign
matter
Electromagnetic fields / static
charging in the vicinity
Balance display not set to zero
Calibration is outdated
Great fluctuations in temperature
Electromagnetic fields / static
charging in the vicinity
Switch off the balance if other error messages appear and then
switch it on again.
Contact the manufacturer if the error message re-appears again
after switching on.
Page 6 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.8.
Valid for:
2 years from
approval
Flow Charts
5.8.1.
Installation
Start
Place balance on firm level surface,
away from any vibrations
Manipulate foot screws at bottom of
balance until air bubble in spirit level
is in the displayed circle
No
Using electrical
power supply
Insert rechargeable batteries
Yes
1
Attach mains adaptor to balance and
then to mains supply
Switch on mains supply
No
Check adaptor is correctly inserted
into balance and mains supply
[*] displayed
Yes
1
Press On/Off Key to turn on balance
Allow balance to warm up for about
10 minutes
No
[0] displayed
Close all draft shields
Yes
Wait until balance displays [0.000]
No
[0.000] displayed
Yes
End
Page 7 of 13
Press TARE Key to reset balance
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.8.2.
Configuration
Start
Press F Key for about 4 seconds until
[FUNC] appears
Press F Key repeatedly until desired
configuration parameter is displayed
(see SOP/PD/310_02/A1)
Press TARE Key repeatedly until
desired number, corresponding to a
particular function, is displayed
Press S key to save chosen function
and return balance to weighing mode
End
Page 8 of 13
Valid for:
2 years from
approval
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.8.3.
Valid for:
2 years from
approval
Operation
Start
No
Desired weighing
unit displayed
1
Press F Key for about 4 seconds until
[FUNC] appears
Yes
No
Using Tare
function
Place sample onto weighing pan,
close all draft shields and
read off value
Yes
Press F Key repeatedly until [S.u.] is
displayed
Press TARE Key repeatedly until the
number that corresponds with the
desired weighing unit is displayed
Place empty weighing container on
weighing pan
Press S key to save and return
balance to weighing mode
Press TARE Key
1
Place sample in weighing container
Close all draft shields and read off
tared value
Use tare function repeatedly
if necessary
End
Page 9 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.8.4.
Valid for:
2 years from
approval
Calibration
Start
Choose an appropriate
calibration weight
1
Press and hold F Key until [CAL] is
displayed
Press and hold F Key while holding
down TARE Key
Subsequently release both keys
simultaneously
Place desired calibration weight on
weighing pan
No
No
Calibration weight
value displayed
Yes
[-Err] displayed
Wait until calibration weight value is
displayed
Remove calibration weight
2
Yes
2
Remove calibration weight from
weighing pan
Wait until balance returns back to
weighing mode
Wait until balance returns to
weighing mode before further use
1
No
Repeat calibration
with different
standard weight
End
Yes
1
Page 10 of 13
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
5.8.5.
Valid for:
2 years from
approval
Maintenance
Start
No
Balance requires
cleaning
1
Yes
Disconnect balance from mains
supply
No
Any surrounding
powder
Yes
Remove using a clean fine brush
No
Any spilt material
Yes
Remove using a moistened cloth with
a mild cleaning agent
No
Air bubble in spirit
level in the centre
of displayed circle
1
Yes
End
Page 11 of 13
Manipulate foot screws at bottom of
balance until this is achieved
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
Valid for:
2 years from
approval
6. Precautions
6.1.
Avoid extreme heat as well as temperature fluctuations caused by
installing next to a radiator or from direct sources of sunlight.
6.2. Protect the balance from air draughts due to open windows and doors.
6.3. Keep weighing pan clean and dry to prevent inaccuracies.
6.4. Do not move balance during weighing.
6.5. Ensure that the maximum tolerated weight of 120g is not exceeded
during weighing procedures and also when using the tare function.
6.6. When transferring balance to a significantly warmer environment,
allow it to acclimatise for approximately 2 hours at room temperature
after it has been disconnected from the mains.
6.7. If using rechargeable batteries to operate balance, charge these for at
least 8 hours, using the mains adaptor, before using it for the first time.
6.8. Do not leave a permanent load on the weighing pan.
6.9. Only use balance if spirit level is correct.
6.10. Adjust the air bubble in the spirit level each time the balance is to be
moved to another location.
6.11. Avoid static charging of the material to be weighed, the weighing
container and the draft shield.
6.12. Do not place in a location where there are possible electromagnetic
fields, static charging and / or an unstable power supply since these
may all cause major display deviations.
7. References
KERN.Operating Instruction Precision balances KERN® EW/EG-N/EWB.
Balingen: KERN and Sohn GmbH; 2006.
8. Appendices
SOP/PD/310_02/A1 – Configurations Parameter Table
9. Revision History
Version Number
01
02
Page 12 of 13
Amendments/ Reasons for change
Initial Release
Inclusion of subheading titles of
Procedure section in Table of Contents
Update of entire SOP to version 2
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/310_02
STANDARD OPERATING PROCEDURE
KERN® EW 120-4NM
PRECISION BALANCE
Valid for:
2 years from
approval
SOP/PD/310_02/A1 – Configuration Parameters Table
Configuration
Parameter
Display Symbol
Function
Bar Graph (to display
weighing range)
b.G.
[0] Turn off bar graph display
[1] Turn on bar graph display
Zero Alignment
A.O
[0] To perform no zero correction
[1] To activate automatic zero
correction
point
Automatic shut-off
after 3 mins when
using rechargeable
batteries
A.P.
[0] Automatic shut-off deactivated
[1] Automatic shut-off activated
Display Speed
rE.
Ranging from sensitive and fast [1] for very
tranquil installation locations to non-sensitive
but slow [5] for very unsettled installation
locations
Vibratory Filter
S.d.
Ranging from sensitive and fast [1] for very
tranquil installation locations to non-sensitive
but slow [5] for very unsettled installation
locations
Weighing unit
S.u.
Baud Rate
b.L.
[01] gram (g)
[14] carat (ct)
[15] ounce (oz)
[16] pound (lb)
[17] troy ounce (ozt)
[18] penny weight (dwt)
[19] grain (►)
[1A] Hong Kong tael (tlH)
[1b] Malaysian tael (tlM)
[1C] Taiwan tael (tlT)
[1d] momme (mom)
[1E] Indian tola (to)
[1] 1200bps
[2] 2400 bps
[3] 4800 bps
[4] 9600 bps
Parity
PA.
[0] No parity
[1] Odd parity
[2] Even parity
Page 13 of 13