1.0 OBJECTIVE

1.1 To lay down the procedure for operation, calibration and cleaning of different models of Balances.

2.0 SCOPE

2.1 This procedure is applicable for operation, calibration, and cleaning of different models of Balances located in the Microbiology Department of AET Laboratories Private Limited.

3.0 RESPONSIBILITIES

3.1 Microbiology analyst shall be responsible to follow the procedure as per the SOP.

3.2 Quality Control / Analytical Development personnel shall be responsible for the preventive maintenance activity.

4.0 ACCOUNTABILITY

4.1 Head/Designee – Microbiology.

5.0 PROCEDURE

5.1 Preliminary Check

5.1.1 Check and ensure the balance and its surrounding areas are clean and suitable for usage.

5.1.2 Use a soft brush for cleaning the pan and its surroundings and verify the calibration status.

5.1.3 Check the spirit level of the balance; if it is in the center, proceed for operation. If not in the center position, adjust it using the leveling feet.

5.1.4 Ensure that the total weight shall not exceed the minimum and maximum operating range of the balance.

5.1.5 Before weighing, bring the temperature of the material to be weighed to room temperature, if required.

5.1.6 Display the operation range of the balance with minimum and maximum weights (e.g., Range: 10g – 500g).

5.2 Cleaning

5.2.1 Ensure the power supply is switched ‘OFF’ before cleaning or preventive maintenance.

5.2.2 Clean the pan and inside of the balance with a lint-free cloth.

5.2.3 Use a soft brush for cleaning the pan and its surroundings.

5.2.4 Make an entry in the balance instrument usage logbook after cleaning. Cleaning activity shall be entered at the start and end of the shift.

5.2.5 Precautions must be taken to ensure no liquid enters the internal mechanism during cleaning.

5.3 Operating Procedure for Make: SARTORIUS | Model: SECURA 224-10IN

5.3.1 Ensure the cleanliness of equipment and platform; it should be clean and dry.

5.3.2 Check the spirit level; the bubble should be in the center of the circle.

5.3.3 Switch on the main power supply; the display shows “Secura”.

5.3.4 Slightly press the ON/OFF key and allow it to stabilize for 2-5 minutes.

5.3.5 When display shows “Leveling”, press the leveling icon. Ensure the bubble shows green.

5.3.6 Select the menu key on the bottom left of the weighing screen.

5.3.7 Menu Applications:

• Mixing: Weigh up to 99 components sequentially. The balance tares automatically after each.
• Statistics: Save and statistically analyze up to 99 components.
• Density: Determine density of solids using Archimedes’ Principle.
• Percentage: Determine percentage share/difference relative to a reference.
• Check Weighing: Check if sample falls within specified tolerances.
• Counting: Determine piece count of objects with equal weight.

5.4 Sample Weighing

5.4.1 After calibration, press the Tare/Zero key. Wait for a stable zero reading.

5.4.2 Place the sample/container in the center of the pan. Close the draft shield window.

5.4.3 Wait for stabilization, then record the weight. Clean the balance after weighing.

5.4.4 Put the balance in standby mode when not in use.

5.5 Data Printer Operation

5.5.1 Connect the printer and switch on the power. Green light indicates readiness.

5.5.2 Press the “Print” button to generate the header (Date/Time).

5.7.1 Daily Calibration (Self-Calibration)

5.7.1.1 Perform self-calibration daily after 30 minutes of warm-up.

5.7.1.2 Select “CAL” from the menu and press “CAL-Intern”.

5.7.1.3 Verify weights: 0.1g, 1g, 10g, and 200g. Record in Annexure-01.

5.7.1.4 Acceptance Tolerance: Variation should not exceed ± 0.1% of certified value.

5.7.2 Monthly Calibration

5.7.2.1 Sensitivity: Place 200g weight. Limit: ± 0.05%.

5.7.2.2 Eccentricity: Place 100g weight in center and 4 corners. Limit: ± 0.05%.

5.7.2.3 Repeatability: 10 weighings of 200mg weight. Limit: ± 0.10% (Uncertainty).

5.7.2.4 Linearity: Test 100mg, 200mg, 500mg, 1g, 100g, 200g. Limit: ± 0.05%.

6.0 ABBREVIATIONS

• SD: Standard Deviation
• QA: Quality Assurance
• MB: Microbiology
• AD: Analytical Development

8.0 ANNEXURES

• Annexure-01: Analytical Balance Daily Calibration Record
• Annexure-02: Analytical Balance Monthly Calibration Record
• Annexure-03: Cleaning and Operation Log