CALIBRATION OF VACUUM GAUGES

1.0    PURPOSE:    
    To describe a standard operating procedure  for the calibration of vacuum gauges.
2.0    SCOPE:
        The standard operating procedure describes in detail the method for the calibration of vacuum gauges in the plant.    
3.0    RESPONSIBILITY:    
    The  responsibility of  calibrating the gauges 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    Use vacuum pump to calibrate the vacuum gauges.    

4.2    Fix a U-tube manometer which is calibrated to the National physical laboratory or their authorized agency and the gauge to be calibrated to the manifold, where comparison between the two gauges shall be carried out by applying vacuum.    
4.3    Apply the vacuum by opening the manifold valve which is provided on the vacuum pump. 
    4.4    Note down the vacuum readings displayed by manometer and the gauge which is to be calibrated at different vacuum from minimum to maximum range of the gauge.  Record the readings in the format xxxxx shown in Annexure-I.   

4.5    Acceptance criteria:

Vacuum gauge range                                   Acceptance criteria

 0    to   760  mm of Hg                                 ±  10 mm of Hg

4.6    During the calibration, if the gauge 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 gauge.    If not possible for repairing the gauge inside the premises, send it to the outside agency for necessary repairs.

4.7    When the gauge is damaged or replaced within the calibration due date, it shall be recalibrated and recorded as per format xxxxx shown in Annexure-II and also entered in the history card of the gauge.
    
4.8    Apart from this recalibration, the calibration shall be followed as per regular schedule.

4.9    Calibration tag for vacuum gauge shall be tied to the gauge with the following particulars. (Whenever there is no error in the gauge white coloured tag shall  be  tied to the gauge.  If there is an error and it is within the acceptable range,  pink coloured tag shall be  tied to the gauge).

    CALIBRATION TAG FOR VACUUM GAUGES
        
    •        Vacuum gauge No    :
    •        Location    :
    •        Calibration / Operating range    :
    •        Difference     
    •        Acceptance Criteria    :
    •        Date of calibration    :
    •        Next due date of calibration     :
    •        Calibrated / Recalibrated by    :
    •        Signature    :

4.10    Frequency: Calibration shall be once in two months ± 2 days.
    
5.0    RECORDING:    
    The responsibility of recording the calibration readings as per Annexures lies with the staff of rank not lower than supervisor of maintenance department.      

Vacuum gauges, engineering, u-tube manometer