POLICY/PROCEDURE TITLE:
C Equipment
POLICY/PROCEDURE #
SOP C04
Page 1 of 3
Pre-Requisite Program
C 1.2.3 Equipment
Calibration
AUTHORIZED FOR USE AT:
ISSUED BY:
DATE ISSUED:
Name
July 24, 2008
APPROVED BY:
SUPERSEDES:
Name
New
Company XYZ
C 1.2.2
The manufacturer has an effective calibration program for equipment monitoring and/or
controlling devices that may impact on food safety.
Standard - identifies food safety equipment requiring regular calibration checks.
Describes how the calibration checks are conducted. Criteria describes procedures for
performing each calibration check.
Frequency:
Digital Thermometers – once a day
Scales – once a week
pH Meters – twice a day
Persons Responsible:
QA Manager and/or QA Technician
Monitoring Procedure:
Thermometers
Only digital thermometers can be calibrated. The probe and dial thermometers cannot be
calibrated. However, their accuracy may be checked.
http://www.oznet.ksu.edu/library/fntr2/mf2439.pdf
1. Quality Assurance personnel will use either the ice-point method or boiling-point
method to verify the accuracy of food thermometers. This is known as calibration of
the thermometer.
2. To use ice-point method:
 Put some ice into a container.
 Add some water to make an ice bath/slush mix.
 Immerse at least one inch of the stem of the thermometer into the slush mix
without touching the sides or bottom of the container.
 Press and hold the ON/OFF button and allow the temperature reading to stabilize
(about 8 sec).
 “CAL” will be displayed on the upper right corner of the LCD.
 Note the temperature in the ice bath with other thermometer – glass or probe.
 Press the calibrate “CAL” button when the display reads 32°F (+/- 2°F) or 0°C
(+/- 1°C). If not, adjust according to manufacturer’s instructions.
 Thermometer is now calibrated.
 Switch off the thermometer. It is now ready for use.
3. To use boiling-point method:
POLICY/PROCEDURE TITLE:
C Equipment
POLICY/PROCEDURE #
SOP C04
Page 2 of 3
Pre-Requisite Program
C 1.2.3 Equipment
Calibration
AUTHORIZED FOR USE AT:
ISSUED BY:
DATE ISSUED:
Name
July 24, 2008
APPROVED BY:
SUPERSEDES:
Name
New
Company XYZ


Put some water into a container. Bring it to a boil.
Immerse at least one inch of the stem of the thermometer into the boiling water
bath without touching the sides or bottom of the container.
 Press and hold the ON/OFF button and allow the temperature reading to stabilize
(about 8 sec).
 “CAL” will be displayed on the upper right corner of the LCD.
 Note the temperature in the boiling water bath with other thermometer – glass or
probe.
 Press the calibrate “CAL” button when the display reads 212°F (+/- 2°F) or
100°C (+/- 1°C). This reading may vary at higher altitudes. If adjustment is
required, follow manufacturer’s instructions.
 Thermometer is now calibrated.
Switch off the thermometer. It is now ready for use.
Electronic Scales
Electronic scales cannot be calibrated, their accuracy are only checked by weighing /
using different weights. Dial scales are adjusted by setting their knobs.
1. Quality Assurance personnel will use a set of standard weights to verify the accuracy
of weighing scales. This is known as calibration of the weighing scale.
2. Take different weights – 200 g, 500 g, 1 kg, 2 kg.
3. Turn ON the scale and first weigh 200-g weight. If the reading is 200 g, it shows
100% accuracy. Record the reading on the Scales Calibration Form.
4. Similarly, put another weight (500 g). Check the reading and record on the Form.
5. Change the batteries when the “LO” is displayed on the display panel.
6. For dial scales, adjust the needle to zero before weighing out different weights (2-kg
and 4-kg).
pH Meters
1. Turn on the pH meter by pressing the MODE button.
2. Press the MODE button again and hold until “CAL” is displayed on the
lower LCD. The LCD will display “OFF” followed by “CAL”. Release
the button when “CAL” is displayed.
3. Once the button is released, the LCD will display “pH 7.01 USE”.
4. Immerse the electrode in pH 7.01 buffer solution.
5. The pH meter will recognize the buffer and then display “pH 4.01 USE”.
6. Rinse the electrode thoroughly with water to eliminate crosscontamination. Wipe it dry.
7. Immerse the electrode in pH 4.01 buffer solution.
POLICY/PROCEDURE TITLE:
C Equipment
POLICY/PROCEDURE #
SOP C04
Page 3 of 3
Pre-Requisite Program
C 1.2.3 Equipment
Calibration
AUTHORIZED FOR USE AT:
ISSUED BY:
DATE ISSUED:
Name
July 24, 2008
APPROVED BY:
SUPERSEDES:
Name
New
Company XYZ
8. When the pH 4.01 buffer is recognized, the LCD will display “OK” for 1
sec.
9. The pH meter is now calibrated and returns to normal measuring mode.
Corrective Action:
1. If a calibration equipment is found unsatisfactory, then;
 Discontinue using the inaccurate equipment and follow manufacturer’s calibration
instructions.
 Replace calibration equipment that is not effectively calibrated
 Record corrective actions on calibration record of respective equipment.
2. QA Department will retrain employees found not following the procedures in this
SOP.
Verification:
The QA Manager will verify that QA Technicians are calibrating equipment according to
the SOP by making visual observations during the calibration process at least once a
month.
Records:
Thermometer Calibration Record
Scale Calibration Record
pH Meter Calibration Record