Calibration

Calibration of Infrared Thermal Camera Using the Black Box Method

Applies To: Infrared Thermal Imaging Devices (e.g., FLIR)

Calibration Method: Black Box (Thermal Reference Source)

Standard Reference: NATA Certification or Traceable Calibration

Permitted Tolerance: ±1°C

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1. Purpose

To ensure accurate and reliable thermal readings from infrared cameras used in food safety monitoring by performing a three-point calibration using a thermal black box.

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2. Required Equipment

• Infrared Thermal Camera (e.g., FLIR)

• Certified Thermal Black Box

  • Preferably NATA-certified (three-point calibration)

  • If not available, must be traceably calibrated

• Tripod or camera mount

• Calibration log or digital record

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3. Calibration Standard

Perform a three-point calibration at the following temperatures:

• 50°C – lower operational limit

• 75°C – for mid-range verification

• 100°C – upper operational limit

Allowable variance: ±1.0°C at each point

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4. Calibration Procedure

Step 1: Preparation

• Power on the black box and allow it to stabilize at each calibration temperature.

• Mount the infrared camera securely on a tripod or level surface.

• Set the camera’s emissivity setting to match the black box surface (typically 0.95 unless otherwise specified).

Step 2: Calibration at 50°C

• Point the camera at the 50°C surface of the black box from approximately 0.3 to 0.5 meter.

• Allow the reading to stabilize and record the temperature displayed.

• If the reading is outside ±1.0°C, adjust the camera per its internal calibration options or document as out of tolerance.

Step 3: Calibration at 75°C

• Repeat the same process for the 75°C zone.

• Record the reading and confirm it is within the allowed deviation.

Step 4: Calibration at 100°C

• Repeat the same for 100°C.

• Log the value and verify the result is within the specified tolerance.

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5. Documentation

Record the following for each calibration point:

• Set point temperature

• Measured camera reading

• Difference (deviation)

• Whether adjustment was required

• Date and technician initials

Use your organization’s calibration form or the Didge platform logging module.

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6. Notes and Considerations

• NATA certification of the black box is preferred. If not feasible, ensure the device has traceable calibration and retain certificates.

• Recalibrate the camera:

  • Every 6 months (recommended)

  • After repair or accidental drop

  • If readings are suspected to be inaccurate

• Perform calibration in a stable environment without airflow or reflective interference.

• The thermal imagery units emissivity value must match that of the blackbox calibration unit

  • MyFlir app currently has set emissivity values as follows:

    • Matte e=0.95

    • Semi-matte e=0.90

    • Semi-glossy e=80

    • Glossy e=60

  • There are no current options for further emissivity settings.

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7. Acceptance Criteria

• All three calibration points must read within ±1.0°C of the set point.

• If any point fails to meet criteria:

  • Attempt recalibration

  • If unresolved, flag the camera for service or decommissioning