UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A 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 the Precisa 180A® Precision Balance
5.2. Installation
5.3. Configuration
5.4. Using the Main Menu
5.5. Weighing Mode
5.6. Using the Mode Key
5.7. Calibration
5.8. Maintenance
5.9. Troubleshooting
5.10. Flow Chart
Precautions
References
Appendices
Revision History
Page 1 of 19
2
2
2
4
4
4
5
5
5
5
6
7
8
8
9
17
17
17
17
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A 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 Precisa 180A® 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 Precisa 180A® Precision
Balance.
3. Definitions
3.1.
Adjustable Feet / Levelling Screws: Four circular screws situated at
the bottom of the balance that are manipulated to level the balance out.
3.2.
Automatic Calibration: A calibration procedure that is carried out
automatically by the balance every 24 hours irrespective of whether it
is in standby or weighing mode.
3.3.
Calibration: A procedure performed to check a measuring instrument
against an accurate standard to determine any deviations and correct for
errors.
3.4.
Configuration Parameters: A number of different options that are
used to set the balance according to the user’s preferences.
3.5.
External Calibration: Involves the use of a standard external weight
that must be used in order to carry out the calibration process.
3.6.
Floating Display: A function that enables the balance to adapt its
integration time to the conditions of the environment.
3.7.
Internal Calibration: Involves the use of a standard internal weight
that is used to carry out the calibration process.
3.8.
Main Menu: Allows the user to adapt the balance to his/her changing
requirements and to any peripheral conditions. It consists of 4 main
options:
Page 2 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
Calibration – to carry out the type of calibration previously chosen
from the configuration parameters menu
Program Second Unit of Mode Key – to choose the unit to be set as
Unit2
Floating Display – to choose the desired time for the floating display
i.e. 0.08 seconds, 0.16 seconds or 0.32 seconds
Stability Detector – to choose the desired stability for the balance i.e
Low, Medium or High
3.9.
Mode Key: Allows the user to call up functions which are activated
once this key is released, such as result, time and date printouts as well
as functions that affect the weighing mode such as switching from
Unit1 to Unit 2 or vice versa or else to change between percentage and
counting mode.
3.10. On/Off Key: To switch the balance on or off.
3.11. T-Key: Used to tare the balance when this is in weighing mode. May
also be used to enter configuration menu or main menu, to change from
one parameter to the next in the individual sub-menus, to exit a menu
and also to call up the calibration programme.
3.12. Tare: Allows the balance to display the weight of the sample measured
only and not the combined weight of the sample and its container.
3.13. Unit1: The basic unit in which values are to be displayed in. This can
be set as the gramme [g], grain [GN], penny weight [dwt], troy ounce
[ozt], ounce [oz], pound [lb], carat [ct], metric carat [C.M.], Hong Kong
tael [tlH], Malaysian tael [tlM] or Taiwan tael [tlT].
3.14. Unit2: The secondary unit that can be chosen and programmed in the
main menu. This can be set as one of the units chosen for Unit1 with
the addition of the piece [PCS] or percent [%].
3.15. Weighing Cell: A glass structure surrounding the weighing pan to
reduce inaccuracies that might occur due to air currents or moving
objects.
3.16. Weighing pan: The area on top of which the material to be weighed is
placed.
Page 3 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
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 the Precisa 180A® Precision Balance
Page 4 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
5.2.
Installation
5.2.1.
5.2.2.
5.2.3.
5.2.4.
5.2.5.
5.3.
5.3.4.
5.3.5.
5.3.6.
Press and hold the T key whilst balance is still switched off.
Press the On/Off key while still pressing the T key.
Keep the T key pressed until the desired configuration
parameter is displayed (see SOP/PD/304_02/A1).
Release the T key to access the desired configuration
parameter.
Press the T key briefly but continuously until the desired
function in the configuration parameter is displayed.
Press and hold the T key again to return to main menu. If this is
not pressed for some time, the configuration menu will be
abandoned automatically, and the standard configuration
stored.
Using the Main Menu
5.4.1.
5.4.2.
5.4.3.
5.4.4.
5.5.
Place the balance a stable surface, away from any vibrations.
Turn the adjustable feet/levelling screws at the bottom of
balance clockwise or anticlockwise until the air bubble in the
spirit level is in the centre of the marked circle.
Insert power supply connector in the plug on the rear of the
balance and plug the power supply into the mains supply.
Press the On/Off Key to activate the balance.
Wait until a stable 0.0000 is displayed before use.
Configuration
5.3.1.
5.3.2.
5.3.3.
5.4.
Valid for:
2 years from
approval
Press and hold the T key until the desired option is displayed.
Release the T key to enter the desired sub-menu.
Press the T key briefly but continuously until the desired
parameter in the sub-menu is reached.
Press and hold the T key to return to the main menu. If this is
not pressed for some time, the main menu is automatically
abandoned and the balance enters weighing mode once again.
Weighing Mode
5.5.1.
Ensure that the desired weighing unit is displayed. If this is not
so, press the MODE key until it is displayed if it had been
Page 5 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
5.5.2.
5.5.3.
5.5.4.
5.5.5.
5.6.
Valid for:
2 years from
approval
previously set as the basic unit i.e. Unit1 or as the secondary
unit i.e. Unit2.
Open the top lid of the weighing cell and place sample onto the
weighing pan.
Close lid and read off value.
If using the tare function, place empty weighing container on
the weighing pan, press the T key and then place the sample in
the weighing container, close lid and read of the tared value
from the display.
Use the tare function repeatedly if necessary.
Using the Mode Key
5.6.1.
Counting Mode
5.6.1.1.
5.6.1.2.
5.6.1.3.
5.6.1.4.
5.6.1.5.
5.6.1.6.
5.6.2.
Ensure that ‘PCS’ was previously set as Unit2 from
the main menu.
Place the number of pieces that are required as
reference weight on the weighing pan.
Press and hold the MODE key until [Unit2 PCS] is
displayed.
Release the MODE key to select the reference weight
as the selected number of pieces and also to switch
automatically to Unit2 i.e counting mode.
Remove the number of pieces used to set the
reference weight.
Place the weight that needs to be counted and read
the number of pieces from the display.
Percentage Mode
5.6.2.1.
5.6.2.2.
5.6.2.3.
5.6.2.4.
5.6.2.5.
Ensure that ‘%’ was previously set as Unit2 from the
main menu.
Place the reference weight on the weighing pan.
Press and hold the MODE key until [reF 100%] is
displayed.
Release the MODE key to set the reference weight as
the selected percentage and also to switch
automatically to Unit2 i.e percentage mode.
Remove the reference weight used to programme the
percentage function.
Page 6 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
5.6.2.6.
5.7.
Valid for:
2 years from
approval
Place the desired sample and read the percentage of
the reference weight from the display.
Calibration
5.7.1.
5.7.2.
5.7.3.
5.7.4.
5.7.5.
Press and hold the T key whilst balance is switched off.
Press the On/Off key while still keeping the T key pressed.
Release the T key when [CAL] is displayed.
Press the T key briefly but continuously until the desired
calibration option is reached i.e. an internal calibration [CAL
INT], an external calibration [CAL EXT] or an automatic
calibration [CAL AUT].
Press and hold the T key again to return to the main menu.
5.7.6.
External Calibration
5.7.6.1.
5.7.6.2.
5.7.6.3.
5.7.6.4.
5.7.6.5.
5.7.6.6.
5.7.7.
Allow a ‘warm up’ time of about 10 minutes.
Press and hold the T key until [CAL EXT] is
displayed
Ensure that there is nothing present on the weighing
pan. If pan is not empty, and/or the balance is active,
the digital display [--000g] will continue to flash.
Allow [000g] to be displayed to indicate that zero
point measurement has been carried out.
Wait until balance display flashes [--100g] and then
place the recommended calibration weight (100g) on
the centre of the pan.
Wait until display shows [100.0000g] to indicate that
calibration is finished and balance returns to
weighing mode.
Internal Calibration
5.7.7.1.
5.7.7.2.
5.7.7.3.
Allow a ‘warm up’ time of about 10 minutes.
Press and hold the T key until [CAL INT] is
displayed.
Wait until the balance reverts to weighing mode to
ensure that the internal calibration is completed.
Page 7 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
5.8.
Maintenance
5.8.1.
5.8.2.
5.8.3.
5.8.4.
5.9.
Valid for:
2 years from
approval
Disconnect balance from its power supply before attempting to
clean and leave it in its normal operating position.
Use a clean fine brush to remove any surrounding powder.
Use a moistened cloth with a mild cleaning agent to clean and
remove any spilt material.
Ensure that the air bubble in the spirit level is in the centre of
the marked circle.
Troubleshooting
Fault
Display does not light up
‘OL’ is displayed
-
Possible Cause/s
Balance not switched on correctly
Balance not connected to mains
Power failure
Faulty microfuse
-
Weighing limit has been exceeded
-
Weighing pan and/or pan support has
not been assembled properly
Draught/ air currents present
Vibrations on table/floor
Weighing pan touching a foreign
body
‘UL’ is displayed
Weighing display changes continuously
Result seemingly incorrect
Display flashes continuously during
calibration
Page 8 of 19
-
Balance not tared
Balance not levelled
Outdated calibration
Strong temperature fluctuations
-
Location of balance is undesirable
Calibration weight is too imprecise or
does not correspond to the
recommended one (applies for
external calibration)
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
5.10. Flow Chart
5.10.1. Installation
Start
Place on stable surface, away from any
vibrations
Turn adjustable feet until air bubble in
spirit level is in the centre of the
marked circle
Insert power supply connector in the
plug on rear of balance and plug power
supply into mains supply
Press On/Off Key to activate balance
Wait until a stable 0.0000 is displayed
before use
End
Page 9 of 19
Valid for:
2 years from
approval
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
5.10.2. Configuration
Start
Press and hold T key whilst
balance is still switched off
Press On/Off key while still
pressing the T key
No
Keep T key pressed until desired
menu is displayed
Desired menu
displayed
Yes
Release T key to access its submenu
Press T key briefly but
continuously until desired
parameter is reached
No
Save changes
made
Yes
Press and hold T Key to save and
return to main menu
End
Page 10 of 19
Do not press any keys and allow
balance to automatically return to
weighing mode
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
5.10.3. Using the Main Menu
Start
Press and hold T key
No
Desired option
displayed
Keep T key pressed until desired
option is displayed
Yes
Release T key to enter its submenu
Press T key briefly but
continuously until desired
parameter is reached
No
Save changes
made
Yes
Press and hold T Key to save and
return to main menu
End
Page 11 of 19
Do not press any keys and allow
balance to automatically return to
weighing mode
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
5.10.4. Weighing Mode
Start
1
No
Open top lid of
weighing cell and
place sample
Yes
Place empty weighing container
on balance
Desired weighing
unit previously set
as Unit1 or Unit2
Yes
Yes
Using tare
function
No
No
Desired weighing
unit displayed
Press On/Off key to switch off
balance
Press and hold MODE key
Press and hold T key and
simultaneously press the On/Off
key again
Release MODE key when [Unit1
x*] or [Unit2 x*] is being displayed
Release T key when [Unit1] is
displayed
1
Briefly but continuously press T
key until [Unit1 x*] is displayed
Close lid and read
off value
Press T key
Press and hold T key to save and
return to main menu
Place sample in weighing
container
Allow balance to enter weighing
mode
Close lid and read off value
Press and hold MODE key until
[Unit1 x*] is displayed
Keep on using tare function
repeatedly if necessary
1
End
*
x represents desired weighing unit
Page 12 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
Valid for:
2 years from
approval
PRECISA® 180A PRECISION BALANCE
5.10.5. Using the Mode Key
Start
No
No
Change balance
to counting
mode
Change balance
to percentage
mode
Yes
1
Yes
‘PCS’
previously set as
Unit2 from main
menu
No
‘%’ previously
set as Unit2
from main menu
Press and hold T key until
[Unit2] is displayed
Press T key briefly and
continuously until [Unit2 PCS]
is displayed
Yes
Place number of pieces
required as reference on pan
Yes
Place reference weight on
weighing pan
Press and hold T key to save
and return to main menu
Press and hold MODE key
until [Unit2 %] is displayed
Release MODE key to select
the reference weight and to
switch automatically to Unit2
Release MODE key to set
reference weight as the
selected percentage and to
switch automatically to Unit2
Read the number of pieces
from the display
Press and hold T key until
[Unit2] is displayed
Press T key briefly and
continuously until [Unit2 %] is
displayed
Press and hold T key to save
and return to main menu
Press and hold MODE key
until [Unit2 PCS] is displayed
Remove number of pieces
used to set reference weight
and place the weight that needs
to be counted
No
Remove reference weight and
place desired sample
Read the percentage of the
reference weight from the
display
1
End
Page 13 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
5.10.6. Calibration
Start
Press and hold T key whilst
balance is still switched off
Press On/Off key to turn on
balance while still keeping T
key pressed
Release T key when [CAL] is
displayed
No
No
Perform internal
calibration
No
Perform external
calibration
Yes
Perform automatic
calibration
Yes
Yes
Press T key briefly but
continuously until [CAL INT]
is displayed
Press T key briefly but
continuously until [CAL EXT]
is displayed
Press T key briefly but
continuously until [CAL AUT]
is displayed
Press and hold the T key to
return to main menu
Press and hold the T key to
return to main menu
Press and hold the T key to
return to main menu
Allow balance to ‘warm up’
for about 10 minutes
Allow balance to ‘warm up’
for about 10 minutes
3
Press and hold T key until
[CAL INT] is displayed
Press and hold T key until
[CAL EXT] is displayed
No
Balance
reverted to
weighing mode
Digital display
[--000g]
continues to
flash
Wait until balance reverts to
weighing mode
Yes
Yes
1
Remove anything that may be
present on weighing pan
2
Page 14 of 19
No
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
2
Allow [000g] to be displayed
Wait until display flashes
[--100g]
Place standard 100g on centre
of weighing pan
Wait until display shows
[100.0000g]
Balance returns to weighing
mode
3
1
End
Page 15 of 19
Valid for:
2 years from
approval
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
5.10.7. Maintenance
Start
No
Balance needs
cleaning
Yes
Disconnect balance from
power supply
Leave balance in its normal
operating position and do not
tilt sideways
No
Any
surrounding
powder
Yes
Remove using clean fine brush
No
Any spilt
material
Yes
Remove using a moistened
cloth with a mild cleaning
agent
Air bubble in
spirit level is in
centre of
marked circle
Yes
End
Page 16 of 19
No
Manipulate adjustable feet
until this is accomplished
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
6. Precautions
6.1.
6.2.
Do not install near extremes of heat and cold.
Do not tip the balance on its side since the weighing cell may be
damaged.
6.3. Protect balance from dust and air draughts.
6.4. Keep weighing pan clean and dry to prevent inaccuracies.
6.5. Do not move the balance during weighing.
6.6. Ensure that the maximum tolerate weight of 180g is not exceeded
during weighing procedures and also when using the tare function.
6.7. Do not leave any items on the balance when this is not in use.
6.8. Only use balance if the spirit level is correct.
6.9. Adjust the air bubble in the spirit level each time the balance is to be
moved to another location.
6.10. If an error message is displayed when balance is switched on, switch
balance off and on again. If error message re-appears, contact supplier
for further information .
6.11. Avoid static charge buildup of the material to be weighed and of the
weighing container.
6.12. 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.
7. References
PAG Oerlikon AG. Precisa 180A Operating Instructions. Zurich: Precisa
Gravimetrics AG.
8. Appendices
SOP/PD/304_02/A1 – Configuration Parameters Table
9. Revision History
Version Number
01
02
Page 17 of 19
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/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Valid for:
2 years from
approval
SOP/PD/304_02/A1 – Configuration Parameters Table
Configuration
Parameter
Display Symbol
Function
Basic unit of balance
Unit1
To choose the weighing unit to be set as
Unit1
Calibration
CAL
To choose from different degrees of
calibration procedures i.e. internal calibration
[CAL INT], external calibration [CAL EXT],
automatic calibration [CAL AUT] and no
calibration [CAL no]
Baudrate
bdr
To choose the desired baudrate from [300
bdr], [600 bdr], [1200 bdr], [2400 bdr],
[4800 bdr] or [9600 bdr]
Parity
PAr
To choose between having no parity [PAr
no], an odd parity [PAr odd] or an even
parity [PAr E]
Printing
Print
To choose between no printing [Print no],
single printout of each value [Print UST],
single printout of each stable value [Print
ST], auto printout after changing load [Print
Lch] or continuous printout [Print PEr]
Combined print
function
Prt-ALL
To combine a printout with weighing result,
date and time etc [Prt-ALL YES] or else to
disable this function [Prt-ALL no]
Delay Printout
Prt-dEL
To delay printout by 0.5, 1 or 2 seconds or
else to disable this delay function [Prt-dEL
no]
Last Digit
LASt d
To choose whether the last digit is to be
always visible [LASt d on] or only visible
when stable [LASt d off]
Automatic zero
adjustment
Signal Sound
A-ZEro
To choose whether this is to be switched on
[A-ZEro on] or off [A-ZEro off]
To switch the sound on [Sound on] or off
[Sound oFF]
To set the time and date
Date/Time Adjustment
Sound
SEt D + T
Page 18 of 19
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/304_02
STANDARD OPERATING PROCEDURE
PRECISA® 180A PRECISION BALANCE
Configuration
Parameter
Menu Inhibit
Status Printout
Valid for:
2 years from
approval
Display Symbol
Function
LAtch
To choose whether to inhibit changes from
being made to the configuration parameters
menu [LAtch on] or else to disable this option
[LAtch oFF]
StAtUS Prt
To perform a printout of all the information
available about the balance including the
parameters that are set in the main and
configuration menus
Page 19 of 19