SOP for Calibration of Thermometer

1.0 OBJECTIVE

To describe the procedure for calibration of the thermometer.

2.0 SCOPE

This SOP is applicable for calibration of the thermometer.

3.0 RESPONSIBILITY

Quality control executive

4.0 ACCOUNTABILITY

Manager – Quality control

5.0 PROCEDURE

5.1 Calibration Procedure

5.1.1 The thermometer for calibration shall be mercury in glass type.
5.1.2 Take a 1000 ml beaker filled with about 850 ml of Silicon oil. Use water for (0–0°C) and silicon Oil for the temperature above 50°C.
5.1.3 Put the beaker in an oil bath fitted with a stirrer. The stirrer shall be dipped in the beaker leaving about 2 cm space from the bottom of the beaker.
5.1.4 Immerse the standard thermometer certified by Approved Laboratory, into the silicon oil vertically approx. 8.0 cm leaving the remainder of the stem and the upper expansion chamber exposed to ambient temperature. Clamp tightly.
5.1.5 Immerse the thermometer to be calibrated into the silicon oil vertically. The mercury bulb of the thermometer shall be placed at the same level of the mercury bulb of the standard thermometer. Clamp tightly.
5.1.6 In case of minimum/maximum thermometers, at the time of calibration, ensure that both the arm should show the same temperature.
5.1.7 Start the stirrer taking precaution that it does not touch the thermometers.
5.1.8 Start heating the oil bath at the rate of 2°C per minute and compare the temperature observed at different increments (Annexure - I).
5.1.9 The temperature difference shall not be more than ±2°C. Any thermometer found beyond the acceptable limit shall be discarded. .

5.2 Identification Number

5.2.1 Identification number shall have 8 characters.
5.2.2 The first two character shall always be T and C respectively.
5.2.3 The third character shall be dash (-).
5.2.4 The fourth & fifth character shall be numeric and denote original number.
5.2.5 The sixth character shall be slash (/).
5.2.6 The seventh & eighth character shall be numeric and shall denote number of re-calibration.
5.2.7 A typical example shall be as follows: TC-01/01
5.2.8 The thermometer shall have an identification number and standardization date labeled on it.
5.2.9 All thermometers shall be standardized once a year and calibration record maintained (Annexure - II).
5.2.10 Standard thermometers shall be sent for re-standardization based on the calibration certificate given by the Approved Laboratory.
5.2.11 Alternatively calibrated thermometer can also be used.

6.0 ABBREVIATIONS

6.1 SOP - Standard Operating Procedure
6.2 No. - Number
6.3 QA - Quality Assurance
6.4 NA - Not Applicable
6.5 CCF - Change control format
6.6 QC - Quality Control
6.7 R&D - Research and Development

ANNEXURE – I

S. NO.	RANGE OF THERMOMETER	SET TEMP. FOR STANDARDISATION
1	- 10°C to 50°C	i)  12°C  ii)  25°C iii) 38°C iv) 50°C
2	- 10°C to 110°C	i)   25°C ii)  50°C   iii) 80°C  iv) 110°C
3	- 10°C to 250°C	i)    60°C ii)  120°C iii) 180°C iv) 220°C
4	- 10°C to 360°C	i)    60°C ii)  120°C iii) 180°C iv) 250°C

Note:  If a pre-certified/calibrated thermometer is used the range given in the certificate shall be used for standardization instead of above set temperatures.

ANNEXURE - II

STANDARDISATION RECORD

NAME OF EQUIPMENT                     :  THERMOMETER

THERMAMETER Sr.No                      :

FREQUENCY                                      :  YEARLY

IDENTIFICATION NO. OF STD. : 

THERMOMETER

DATE OF STANDARDISATION	THERMOMETER NO.	SET TEMP.	STANDARD THERMOMETER	OBSERVED GAUGE IN MM	THERMOMETER TO BE STANDARDISED	REMARKS	CALIBRATED BY	CHECKED BY
			CORRECTION TO READING	ACTUAL TEMP.	TEMP. OBSERVED	CORRECTION TO READING

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