SOP Title: Operation, Cleaning and Calibration of Analytical weighing Balance

SOP Title: Operation, Cleaning and Calibration of Analytical weighing Balance

Objective:

To lay down the procedure for Operation, Cleaning and Calibration of Analytical weighing Balance.

Scope:

This SOP is applicable for Operation, Cleaning and Calibration of Analytical weighing Balance located in Quality Control Laboratory.

Responsibility:

Quality Control Department: To prepare and review the SOP. To follow the procedures laid down for Operation, Cleaning and Calibration of Electronic Weighing Balance as per this SOP.
Engineering Department: To carry out preventive maintenance as per schedule and procedure defined.
Quality Assurance Department: To review and approve the SOP and Annexures.

Accountability:

Head Quality Control Department, Head Quality Assurance Department

Procedure:

5.1

Safety Precautions/Instructions:

5.1.1

Ensure all the electrical connections are properly earthed. Ensure the power plug of the Electronic Balance is fixed in the socket properly.

5.1.2

Wear personal protective equipments such as safety glasses, hand gloves, nose mask during operation of instrument.

5.1.3

Ensure that the ON/OFF switch is working properly by switching “ON” the Electronic Balance.

5.1.4

Analysts must be familiar with precautions described in respective Material Safety Data Sheet of the materials before weighing it.

5.1.5

Do not unplug the power or shift the balance when ‘CAL’ is Displayed on display

5.1.6

Check that the balance is kept vibration free table/platform.

5.1.7

Analytical weighing Balance Maximum range is 220 gm and Minimum range is 0.1 gm, do not exceeds the maximum weight limit. Weighing range is 10 mg to 150 gm

5.1.8

Never weigh any material directly on weighing pan, instead use butter paper or any other suitable container.

5.2

Introduction to the Keys of Analytical weighing Balance:

5.2.1

During measurement

5.2.2

Key	Pressed Once And Released	Pressed And Held For About 3 Seconds
[POWER]	Switches between the operation and standby modes.	Switches the key notification buzzer on/off.
[CAL]	Enter calibration or menu item selection.	Enter calibration or menu item selection.
[O/T]	Tares the balance. (Displays zero.) ^*1	NA
[UNIT]	Switches the units of measurement	NA

5.2.3

Key

Pressed Once And Released

Pressed And Held For About 3 Seconds

[PRINT]

Outputs the displayed values to an electronic printer computer, or other external devices.^*2,

Outputs the date and time to external devices

[1d/10d]

Switches display between 1d/10d. (Minimum display is rounded by one digit.)

During Menu Item Selection:

5.2.4

Key	Pressed Once And Released	Pressed And Held For About 3 Seconds
[POWER]	Return to the menu above the current menu level.	Returns to mass display.
[CAL]	Moves to the next menu item.
[O/T]	Select or set the displayed item, or enter into the displayed menu.
[UNIT]	Numerical value input, increases the numeric value of the blinking digit by 1.
[PRINT]	Numerical value input, moves the blinking digit.
[1d/10d]	No effect.

5.3

Operational Procedure:

5.3.1

Check the validity of calibration before starting any operations.

5.3.2

Level the balance using levelling feet so that level indicator bubble is centered within the circle of levelling indicator.

5.3.3

Check the cleanliness of the Balance and its surrounding area.

5.3.4

Connect the power supply cord to the switch board and switch on the balance and allow the balance to warm up for about 30 minutes.

5.3.5

Plug The AC adapter to the power outlet

5.3.6

After the balance performs a self check, calibration will be automatically executed, it returns to the mass display and span calibration is complete.

5.3.7

During this process, the display will change as follows.

“CAL 2” “CAL 1” “CAL 0” “CAL END” “OFF”

5.3.8

Press “POWER” key to appears the gram (g) on displays.

5.3.9

Pressing the [POWER] key again turns on the standby symbol and puts the balance in standby (warm up) status.

5.3.10

The current time is display according to the built-in clock setting

Note: For accurate measurement, perform span calibration again when the balance is moved or when the temperature of the installation site has changed.

Sample weighing on Balance:

5.3.11

Open one of the glass doors of the weighing chamber, place the weighing vessel (container) on the pan, and close the glass door again. (When using a container)

5.3.12

Wait for the display to stabilize and press the [O/T] key (taring). The appearance of the stability mark ( ) indicates a stable state. The display will read zero.

5.3.13

Open the glass door, place the items to be weighed in the weighing vessel and close the glass door.

5.3.14

After the display stabilizes, read the display.

5.3.15

If beaker/flask/evaporating dish is taken for weighing as the receiver then receiver’s weight plus the material’s weight should not exceed the capacity of the balance.

5.3.16

Butter paper should be used when small amount of materials are to be weighed.

5.3.17

Before weighing any materials which has been heated or stored in refrigerator, they should be brought to the room temperature and weighed.

5.3.18

Printer connected to the Analytical weighing Balance.

5.3.19

After material weigh, display will stabilize, go to printer and Press “ID” key and Press “Date” key. Green light will blow on both keys.

5.3.20

Before going to the “STAT” option, switch off green light by pressing both “ID” key and “Date” key.

5.3.21

Press “STAT” key located on the printer. It will appears on paper print.

5.3.22

Press “PRINT” key located on the Analytical weighing Balance to take weight print on paper print.

5.3.23

After sample weighing finish, Press “STAT” key located on the printer.

5.3.24

Update the “Instrument/Equipment Usage Log Book” as per SOP “Calibration of Instruments and Equipments”.

Note:1) Except when placing or removing items or calibration weights to and from the weighing chamber, keep the glass doors closed

2) Air convection causes measurement error if the temperatures of the weighed item and the chamber are different. In order to avoid this, equalize the temperatures by leaving the item in the extra space within the chamber before weighing.

Changing the Unit Display:

5.3.25

Pressing the [UNIT] key switches display between the registered units, piece counting and specific gravity measurement modes.

Note: The units to be used must be registered in the system

Menu Item Selection Procedures:

5.3.26

Press the [CAL] key from the mass display. “i-CAL” appears.

5.3.27

After that, pressing the [CAL] key changes the display in the order shown below.

5.3.28

00000

Mass display

CAL

Execute the preset calibration method

SET in I

Windows Direct setting (down)

SET in-

Windows Direct setting (right)

SE BIE

Settings check display

Stnd

Standard mode

PoUr

Pouring mode

Con Ect

Anti-convection mode

Hi stb

High-stability mode

Fu Sel

Entry to second level

(application measurement, individual settings menu group)

SETT inG

Entry to second level (system settings menu group)

int FACE

Entry to second level (communication settings menu group)

00000

Mass display

Setting the Built-in Clock:

5.3.29

To set the clock From the mass display, press the [CAL] key repeatedly until “SEttinG” appears, press the [O/T] key. “CAL dEF” will appear.

5.3.30

Press the [CAL] key repeatedly until “d-MM.DD” appears (MM and DD are each two digits representing month and date, respectively), and press the [O/T] key. In the upper part of the display, the mark and the symbol appear indicating number entry mode. Also, the current date setting

5.3.31

appears as [YY.MM.DD] (YY is the year) with the leftmost digit blinking.

5.3.32

Pressing the [UNIT] key increases the blinking digit by one. Pressing the [PRINT] key moves the blinking digit one place to the right.

5.3.33

Press the [O/T] key when the desired date is shown in the display. The built-in clock will be set.

5.3.34

Press the [POWER] key repeatedly to return to the mass display

Date Output Style:

5.3.35

The order of the year, the month and the date in the external output can be selected from three styles

5.3.36

From the mass display, press the [CAL] key repeatedly until “SEttinG” appears, press the [O/T] key. “CAL dEF” will appear

5.3.37

Press the [CAL] key repeatedly until “StyL.dAtE” appears.

5.3.38

Press the [O/T] key. The display shows “y-m-d”.

After this, pressing the [CAL] key cycles the dis-plays in the order of “y-m-d” → “m-d-y” → “d-m-y” → “y-m-d”. “y-m-d” is for setting YYYY-MM-DD, “m-d-y” is for MM-DD-YYYY and “d-m-y” is for DD-MM-YYYY. When the current setting is displayed, the stability mark ( ) appears. To change the setting, press the [O/T] key when the desired setting is on the display

5.3.39

Press the [POWER] key to return to “StyL.dAtE” without changing the setting

5.3.40

Pressing the [POWER] key again returns to the mass display

Time:

5.3.41

To set the time, From the mass display, press the [CAL] key repeatedly until “SEttinG” appears. Press the [O/T] key. “CAL dEF” will appear.

5.3.42

Press the [CAL] key repeatedly until “t-HH.MM” appears (HH and MM are each two digits representing hour and minute, respectively), and press the [O/T] key.

5.3.43

In the upper part of the display, the symbol and the symbol appear indicating number entry status. Also, the current time setting appears.

5.3.44

Pressing the [UNIT] key increases the blinking digit by one. Pressing the [PRINT] key moves the blinking digit one place to the right.

5.3.45

Press the [O/T] key when the desired time is shown in the display. The built-in clock will be set.

5.3.46

Press the [POWER] key repeatedly to return to the mass display.

Changing the Minimum Display:

A)To change the minimum display by one digit

5.3.47

Press the [1d/10d] key from the mass display. The minimum display digit will be displayed with only three decimal places.

B)To return the minimum display to the standard setting

5.3.48

Press the [1d/10d] key from the mass display. The minimum display digit will return to the previous setting.

Note: The decimal point does not move. When the minimum display is changed by one decimal place, the final decimal place remains empty.

Balance ID Setting:

5.3.49

To set the balance ID No. From mass display, press the [CAL] key repeatedly until “SEttinG” appears. Press the [O/T] key. “CAL dEF” appears.

5.3.50

Press the [CAL] key repeatedly until “id: ∗∗∗∗” appears. (The ∗∗∗∗ is a number.) Press the [O/T] key. In the upper part of the display panel, the symbol and the symbol appear in order to indicate numerical input mode. The left-most digit of ∗∗∗∗ blinks. The numeral of the blink-ing digit can be changed.

5.3.51

Press the [UNIT] key to increase the value of the blinking digit by 1. Press the [PRINT] key to set that digit and move the blinking digit one place to the right. When the desired setting is entered, press the [O/T] key to confirm the balance ID number.

5.3.52

Press the [POWER] key to return to “id: ∗∗∗∗”. (No blinking)

5.3.53

Press the [POWER] key again to return to the mass display.

Settings for Stability and Response:

A) Standard mode:

5.3.54

Use this mode unless stability or response is affected by environmental factors. From the mass display, pressing the [CAL] key repeat-edly until “Stnd” is displayed. Pressing the [O/T] key here sets the mode to Standard mode

B) Anti-convection mode:

5.3.55

When ambient temperature changes (such as those due to air-conditioner cycling) are unavoidable during measurements, convection may occur in the weighing chamber and cause display fluctuation after the stabil-ity mark appears

5.3.56

From the mass display, press the [CAL] key repeatedly until “ConvECt” is displayed. Pressing the [O/T] key here sets it to Anti-convection mode.

C) High-stability Mode:

5.3.57

Function of this is to reduce the effects of vibration or air current even further. The response will slow slightly but the display will be stabilized.

5.3.58

From the mass display, press the [CAL] key repeatedly until “Hi-Stb” is displayed. Press the [O/T] key here to enter High-stability mode

D) Pouring Mode (fast response):

5.3.59

Press the [CAL] key repeatedly from the mass display until “Pouring” appears.

5.3.60

Pressing the [O/T] key here sets it to Pouring mode and proceeds to “normL.Env” display. the arrow mark indicates that the displayed environmental setting is currently selected. Press [POWER] key to return to the mass display.

5.4

Calibration Procedure:

A) Daily calibration: Performance check

Frequency: First half of every day.

Note: Replace the silica gel on weekly basis (preferably on Monday) or when its appearance changes.

5.4.1

Perform the daily calibration of instrument as per Annexure No. 01 and procedure mentioned below.

5.4.2

Calibration is performed using standard calibrated weight box.

5.4.3

For daily calibration 0.0200 g, 0.1000 g, 1.0000 g, 50.0000 g and 100.0000 g weights are used.

5.4.4

Ensure that the display shows zero reading. If not press ‘[O/T]’ key to zero the display.

5.4.5

Place the standard weights on the weighing pan.

5.4.6

The balance should display the reading within the acceptance criteria specified for each of the standard weight range.

5.4.7

Take weight print of standard weight.

5.4.8

Enter the details in ‘Daily Balance Calibration Record’ as per Annexure No. 01. Ensure that the results obtained, comply with the acceptance criteria.

5.4.9

Update the “Instrument/Equipment Usage Log Book” as per SOP “Calibration of Instruments and Equipments”.

B) Monthly calibration:

Frequency: Monthly or after carrying out any major maintenance work.

5.4.10

Generate the A. R. No. on the “Instrument/Equipment Calibration Register” as per SOP and give requisition to QA Department for calibration formats of instruments on the due date of calibration.

5.4.11

For issuance of calibration report refer QA SOP “Control of documents, Preparation, Approval, Issuance and Maintenance.

5.4.12

Perform the calibration of instrument as per Annexure and procedure mentioned below.

5.4.13

Prepare the “Monthly Calibration Schedule” as per Annexure yearly according to the Validity of weight box.

5.4.14

Calibration of Balance is performed for below parameters:

1. Uncertainty

2. Off Centre and Shift Error

3. Sensitivity check

1. Uncertainty:

5.4.15

Uncertainty is checked using the standard weight 0.500 g.

5.4.16

Ensure that the display shows zero reading. If not press ‘TARE’ key to zero the display.

5.4.17

Keep the standard weight 0.500 g (x_i) on the weighing pan and note down the observed reading (x).

5.4.18

Take 10 replicate readings with the same weight 0.500 g and calculate by using current standard weight (x_i – x)² for every reading.

5.4.19

Take weight print of standard weight

5.4.20

Calculate the Standard Deviation by the formula:

SD = √ ∑ ⁿ ( x _i – x )²

ⁱ⁼¹n -1

Where, ∑ ⁿ ( x _i – x)²= mean of (x_i – x)² for 10 readings.

n = no. of readings taken.

5.4.21

Calculate uncertainty using the formula:

Uncertainty = 3 X SD of 10 Replicate weighing

Standard weight

SD – Standard Deviation

5.4.22

Enter the details in “Monthly Balance Calibration Record as per Annexure. Ensure that the results obtained, comply with the acceptance criteria.Ο

2. Off centre and shift error:

5.4.23

To check off centre and shift error the standard weight 0.0500 g is used.

5.4.24

Keep the weight on weighing pan on five different positions as shown below:

2. 3.

4. 5.

5.4.25

Take weight print of standard weight

5.4.26

Enter the details in “Monthly Balance Calibration Record” as per Annexure No. 02. Ensure that the results obtained, comply with the acceptance criteria.

3. Sensitivity check:

5.4.27

Place the standard weights on the weighing pan on by one as specified in the “Annexure 02”

Note: Use current Standard certified weight for sensitivity range

5.4.28

Take weight print of standard weight.

5.4.29

Enter the Calibrated weight and observed weight with its acceptance criteria in excel sheet.

Linearity Test:

5.4.30

Refer Sensitivity Check test for observed weight and plot the graph on excel sheet and calculate Correlation Coefficient. It should be performed Half yearly. Its acceptance criteria are +1 to -1.

5.4.31

Enter the details in “Monthly Balance Calibration Record” as per Annexure . Ensure that the results obtained, comply with the acceptance criteria.

5.4.32

Update the “Instrument/Equipment Usage Log Book”, “Annual Calibration Schedule” and “Monthly Calibration Schedule” as per SOP “Calibration of Instruments and Equipments”.

5.4.33

Affix the “Calibration Status” on the Instrument as per SOP “Calibration of Instruments and Equipments”.

5.4.34

For out of calibration refer SOP “Calibration of Instruments and Equipments”.

5.4.35

If calibration activity is outsourced, the values are to be transcribed in the Annexure , and external party certificate to be attached.

5.5

Cleaning Procedure:

5.5.1

Cleaning of the Balance should be done daily before calibration and before and after use.

5.5.2

Remove dust and powder with the help of tissue paper or soft nylon brush.

5.5.3

Do not leave anything on the weighing pan after use.

5.5.4

Clean the inside, outside and shutter of the balance with tissue paper or soft cloth soaked and squeezed in IPA to remove any oily substances or spots from the balance.

5.5.5

Then clean the balance with dry tissue paper.

5.5.6

If any breakdown occurs, follow procedure as per SOP “Calibration of Instruments and Equipments”.

Definitions / Abbreviations:

Definitions:
Breakdown: Any activity leading to operation of instrument/equipment other than the set parameters or unusual sound or vibration observed in the instrument/equipment.
Calibration: Tests performed to ensure that the instrument/equipment is functioning as per set parameters. These tests are performed as per predefined frequency and also after any major repair or replacement of parts.
Preventive Maintenance: Maintenance activity performed to ensure that the instrument/equipment will function smoothly and to avoid breakdowns. These activities are performed as per predefined frequency.
Analytical weighing Balanceis a device used to find accurate measurements of weight. It is a class of balance designed to measure small mass in the sub-milligram range.
Abbreviations:

Abbreviation	Expansion
SOP	Standard Operating Procedure
QC	Quality Control
QA	Quality Assurance
CAL	Calibration
IPA	Isopropyl Alcohol
g	gram
A. R. No.	Analytical Reference Number

Daily Balance Calibration Record

Performance Check: Acceptance Criteria: + 0.1%

Date	Zero Error	Standard Weights					Remark	Done by	Checked by
Date	Zero Error	0.0200 g	0.1000 g	1.0000 g	50.0000g	100.0000g	Remark	Done by	Checked by

Monthly Balance Calibration Record

Test for Uncertainty:

Standard Weight as per current certified weight (0.5g):_________g Limit = NMT 0.001

No. of Observations	Weight in gm observed	( x_i– x )²
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

√∑ (x_i– x ) ²=________

SD = ∑ ⁿ ( x _i – x)²=__________

ⁱ⁼¹n -1

SD = 3 X SD of 10 Replicate weighing = ________________

Standard weight

SD= _________________

Checks For Off Centre and Shift Error:

Standard Weight as per current certified weight (0.05g):________g

Limit = Error NMT 0.5 mg

Position of Weight

2. 3.

4. 5.

Sr. No.	Weight in gm observed	Error (NMT 0.5 mg)
1
2
3
4
5

Sensitivity Check: Acceptance Criteria: + 0.1%

Sr. No.	Nominal Weights in gm	Standard Weights in gm (Certified)	Acceptance Criteria w.r.t std. weights in gm	Observation in gm
1.	100.0000 g
2.	50.0000 g
3.	20.0000 g
4.	10.0000 g
5.	5.0000 g
6.	2.0000 g
7.	1.0000 g
8.	0.5000 g
9.	0.2000 g
10.	0.1000 g
11.	0.0500 g
12.	0.0200 g

The results Complies / Does not complies as per acceptance criteria.

Performed By: ________________ Date:___________ Checked By: ______________ Date: ____________

*Note – Ready to use SOP available in “DOWNLOAD” Section.

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