Standard Operating Procedure (SOP)

1. Purpose
The purpose of this SOP is to outline the procedure for calibrating an Infrared Moisture Balance (IMB) to ensure that accurate moisture content readings are obtained.

2. Scope
This SOP applies to the calibration of Infrared Moisture Balances used in the determination of moisture content in samples. The procedure is applicable to all personnel responsible for calibrating the IMB in the laboratory setting.

3. Responsibilities

• Laboratory Technicians: Ensure the proper calibration of the infrared moisture balance and document the calibration results.

• Quality Control Manager: Review calibration records and ensure the instrument’s performance is in compliance with company standards.

4. Equipment and Materials

• Infrared Moisture Balance (IMB)

• Certified Calibration Standard (usually a reference material with a known moisture content, e.g., dried silica gel)

• Weighing scale (calibrated)

• Drying oven (optional, if cross-checking)

• Calibration weights (if needed)

5. Procedure

5.1 Preparation

• Ensure that the Infrared Moisture Balance is clean, dry, and free from any previous samples.

• Verify that the instrument is functioning correctly by performing a general check (screen display, buttons, etc.).

• Set the instrument to the factory settings or calibration mode, depending on the model.

• If the IMB has a drying pan, ensure that it is placed correctly.

• Prepare the certified calibration standard. The standard should be dried to a known moisture content (e.g., silica gel).

5.2 Initial Setup

1. Power On the Infrared Moisture Balance and allow it to warm up, if required, per the manufacturer’s instructions (typically 15 minutes).

2. Set Calibration Mode (if applicable): If your IMB requires a calibration mode to be activated, select this mode from the settings menu.

3. Tare the Balance: Ensure that the balance is tared to zero with no sample in place.

5.3 Calibration with Certified Standard

1. Place the certified calibration standard on the drying pan of the IMB.

2. Close the instrument lid and select the calibration function (if applicable).

3. Start the calibration process and allow the IMB to dry the sample under the predetermined settings (e.g., temperature, drying time). The standard will dry under the preset parameters, and the IMB will determine the moisture content.

4. After the drying process is complete, record the measured moisture content from the IMB’s display.

5. Compare the IMB’s measured moisture content with the known moisture content of the calibration standard.

5.4 Adjust Calibration (if necessary)

1. If the measured moisture content deviates from the known value by more than the manufacturer’s tolerance (usually ±0.1% or as specified), you will need to adjust the calibration settings.

2. Follow the calibration adjustment procedure specified by the manufacturer in the user manual (this often involves entering the calibration mode and adjusting the correction factor or entering the actual moisture content of the standard).

3. After adjustment, recheck the moisture content of the calibration standard. If it is within acceptable limits, the IMB is calibrated.

4. If necessary, repeat the calibration process until the measured value aligns with the standard.

5.5 Document Calibration Results

• Record the date and time of the calibration.

• Record the measured moisture content and the known moisture content of the standard.

• Document any adjustments made to the IMB.

• Sign and date the calibration record.

• Store the calibration results in a logbook or digital records as required by laboratory procedures.

6. Post-Calibration Verification

• After calibration, verify the accuracy of the IMB by testing with a sample of known moisture content.

• The results should be within the expected limits of accuracy.

• If the results are out of range, recalibrate the IMB or refer to the manufacturer’s troubleshooting guide.

7. Frequency of Calibration

• Routine Calibration: Perform calibration at regular intervals as per the manufacturer’s guidelines or standard operating procedures (typically every 6 months).

• Post-Maintenance Calibration: Calibrate after any significant maintenance or repair of the IMB.

• After Significant Use: Recalibrate if the IMB has been exposed to harsh environmental conditions or after use with different types of samples.

8. Safety Precautions

• Handle all calibration standards with care to prevent contamination.

• Follow proper laboratory safety procedures while using the IMB and related equipment.

• Always wear protective equipment (lab coat, gloves, safety glasses) when handling chemicals or equipment.

9. Troubleshooting

• If the IMB does not pass calibration:

  • Check for proper operation of the infrared lamp and drying mechanism.

  • Ensure there is no dust or residue on the pan or sample holder.

  • Review manufacturer troubleshooting guidelines.

  • Contact technical support if needed.

10. References

• Manufacturer’s manual for the Infrared Moisture Balance

• Laboratory equipment calibration records

• Calibration standard certificate (for the certified standard used)

11. Appendices

• Calibration Log Sheet

• Calibration Standard Certificate

• Maintenance Log

This SOP ensures that the Infrared Moisture Balance is accurately calibrated and provides reliable results for moisture content determination.

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