To describe a standard operating procedure for the calibration of Dial temperature gauges with standard zeal thermometers and the calibration procedure for the Digital temperature indicator/controllers with standard RTD simulator.
1.0 PURPOSE :
To describe a standard operating procedure for the calibration of Dial temperature gauges with standard zeal thermometers and the calibration procedure for the Digital temperature indicator/controllers with standard RTD simulator.
2.0 SCOPE:
The standard operating procedure describes in detail the method for the calibration of Dial temperature gauges with standard zeal thermometer and Digital temperature indicator/controllers with standard RTD simulator.
3.0 RESPONSIBILITY:
The responsibility of calibrating the Dial temperature gauges with standard zeal thermometer and Digital temperature indicator/controllers with standard RTD simulator lies with the staff of rank not lower than the supervisor of maintenance department.
The responsibility of preparation, review and approval of the standard operating procedure lies with the Manager – Maintenance, Head of Production and Head of QAD respectively.
4.0 METHOD:
4.1 Calibration procedure for Dial temperature gauges with standard zeal thermometer:
4.1.1 Select a suitable range of standard zeal thermometer, calibration traceability with national physical laboratory
4.1.2 Heat the oil contained in a bath to the temperature nearer to the maximum operating temperature of the gauge. Dip standard zeal thermometer and stem of temperature gauge which has to be calibrated.
4.1.3 Note down 3-4 readings of the standard zeal thermometer and temperature of the under test gauge.
4.1.4 Similarly, take a chilled bath of temperature to the minimum working temperature of the gauge and dip the standard zeal thermometer and stem of temperature gauge which has to be calibrated.
4.1.5 Note down 3-4 readings of the standard zeal thermometer and of the under test temperature gauge. Record the readings in the format xxxxx as shown in Annexure-I.
4.1.6 Acceptance criteria:
The resolution of gauge shall be considered as acceptance criteria for that particular gauge.
? If the gauge is graduated with 1°C resolution, the acceptance criteria shall be 1°C.
?If the gauge is graduated with 2°C resolution, the acceptance criteria shall be2°C.
? If the gauge is graduated with 5°C resolution, the acceptance criteria shall be 5°C.
4.1.7 Whenever the gauge is rectified or replaced with another before the scheduled calibration due date, the same shall be informed to the Quality Assurance Department. Recalibration data shall be recorded as per format xxxxx shown in Annexure-II and also entered in the history card of the gauge.
4.1.8 The recalibration format xxxxx is also shall be used whenever the gauges calibrated for validation purpose. The same shall be remarked in remarks column.
4.2 Calibration procedure for Digital temperature indicators / controllers with RTD simulator.
4.2.1 Select a standard RTD simulator, calibration traceability with national physical laboratory.
4.2.2 Connect the RTD simulator to the Digital temperature indicator/controller cables in place of RTD sensor.
4.2.3 Compare the reading of the Indicator/Controller with standard reading labeled on the simulator by switching ‘ON’ the toggle switch one after the another for 3-4 readings and record the readings in the format xxxxx in Annexure-V.
4.2.4 Acceptance criteria for Digital temperature indicator/controller of range shall be
0.1% of full scale division
4.2.5 Whenever an indicator / controller is rectified or replaced with another before the scheduled due date of calibration the same shall be informed to the QAD. Recalibration data shall be recorded in the format xxxx shown in Annexure-VI and also entered in the history card of the Digital temperature indicator / controller.
4.2.6 The recalibration format xxxxx is also shall be used whenever the indicators/controllers calibrated for validation purpose. The same shall be remarked in remarks column.
4.2.7 All the digital temperature indicators/controllers are calibrated by out side agency in the presence of maintenance department as per the procedure and rectification of the indicator/controller recalibration shall be carried out by maintenance department.
4.3 During the calibration, if the dial temperature gauge/digital temperature indicator/controller does not meet the acceptance criteria, service the gauge, recalibrate and then inform to the QAD for taking necessary action regarding variation of the quality and yields of the batches carried out with that indicator/controller. If the instrument is not possible to repair inside the premises, send it to the outside agency for necessary repairs. If the indicator/controller is not serviceable even at out side agency replace the same.
4.4 Apart from the recalibration of instruments, the calibration shall be followed as per the schedule for all the instruments.
4.5 Calibration tag for Dial / Digital temperature gauge / indicator / controller shall be tied to the gauge with the following particulars.
CALIBRATION TAG FOR TEMPERATURE GAUGE/INDICATOR /CONTROLLER
Temperature gauge / indicator / controller No :
Location :
Calibration / Operating range :
Difference :
Acceptance criteria :
Date of calibration :
Next due date of calibration :
Calibrated / Recalibrated by :
Signature :
4.6 Frequency:
? Calibration of dial temperature gauges shall be once in two months ± 2 days.
? Calibration of digital indicators/controllers shall be once in three months
± 2 days.
5.0 RECORDING:
The responsibility of recording the calibration data as per Annexures lies with the staff of rank not lower than supervisor of maintenance department.
Temparature indicators, temperature gauges, engineering
