SOP for Operation and checking of Precision Balance

1.0 OBJECTIVE : To provide a general guideline for operation and function checking of Precision Balance.

2.0 SCOPE : This SOP is applicable for operation and function checking of Precision Balance, Model No. PB 602-L.

3.1 Operating personnel is responsible for carrying out the procedure.
3.2 Overall responsibility for training, implementation and follow-up with the QC Manager or his nominee.

4.1 Head of Quality.

5.1 Check the leveling of the balance before every weighing. It must be leveled on a stable surface.
5.2 Always place the weight in the center of the pan.
5.3 Never weigh any material beyond the maximum and minimum weight limits indicated on the balance.
5.4 Keep the balance free from vibration.
5.5 Keep the balance free from temperature fluctuation.
5.6 Keep it free from heat radiation.
5.7 Keep it free from aggressive chemical atmosphere.
5.8 Keep it free from moist condition.
5.9 The pan of the balance should be checked to ensure that it is properly seated on the pan mechanism.
5.10 Allow samples/containers to reach to room temperature before weighing. Hot samples will generate an upward convection of warm air that will cause an inaccurate reading.
5.11 Samples that are extremely hygroscopic or lose water rapidly must be weighed in a closed container.
5.12 Fingerprint may cause an inaccurate value. Make sure that hands are clean and dry and do not contribute to the weighing.
5.13 Be sure to use a clean and dry spatula or other transfer device to avoid contamination of the article to be weighed.

6.1 Plug the AC adapter and connect the power supply. Press the On key briefly. To achieve accurate result the balance must be connected to the power supply for 30 minutes.
6.2 Connect the printer to the balance. Turn On power switch of the printer.
6.3 First person who will start the balance will perform the daily calibration and function check and maintain a logbook (As per FRM No.: FQC/060 which is mentioned in SOP No.: QC045).
6.4 Daily Function Check
6.4.1 Check the bubble position of the balance and note down in the log book. Adjust the position if required.
6.4.2 Take 10g, 200g and 500 g certified weight and clean them carefully with a soft lint-free cloth.
6.4.3 Place the weights, one after another, at the centre of the weighing pan and close all sliding window and allow the reading to be stabilized.
6.4.4 Record the value of the weights in the logbook for ‘Daily Function Check of Analytical Balance’ (Annexure-I, FRM No: FQC/060).
6.4.5 The tolerance limit: ± 0.1% to that of specific weight.
6.4.6 The daily function check shall be done at the beginning of each day and the function check shall be valid for 24 hours provided that the balance is not powered off within this period. Before starting to take any weight in the balance, the analyst shall ensure that the function check has been done and it is still within the valid period of time.
6.4.6 The function check shall be done on each working day. However, on the holy days, if any balance is used, its function checking must be done prior to use by the analyst.
6.5 Weighing
6.5.1 Remove all loads from weighing pan.
6.5.2 When zero (0.0 g) reading is displayed, the balance is ready for operation. If the display shows greater than or less than zero press “ O/T ” key.
6.5.3 Place empty container/weighing paper on the balance.
6.5.4 The weight is displayed. Allow the reading to stabilize.
6.5.5 To tare press “O/T” key briefly.
6.5.6 Add weighing sample to the container/paper. The net weight is now displayed. Allow the reading to stabilize. Record the weight. To get printout of the weight, press ‘F’ on the printer.
6.5.7 For performing another weighing press “ O/T ” key and follow steps 6.5.1 to 6.5.6.
6.6 Switch Off
6.6.1 To switch off press and hold the “Off” key down until OFF appears in the display.
6.7 Cleaning
6.7.1 Switch off the balance. Remove all objects from the balance. Clean the pan with soft brush followed by with soft clean cloth.
6.7.2 Clean all of the parts of the balance with clean dry cloth.
6.7.3 Set the parts of weighing pan carefully.

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