CALIBRATION OF PRESSURE GAUGES

1.0    PURPOSE:    
    To describe a standard operating procedure for the calibration of pressure gauges.    
2.0    SCOPE:    
    The standard operating procedure describes in detail the method for the calibration of pressure gauges in the plant.    
3.0    RESPONSIBILITY:    
    The responsibility of calibrating the pressure 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    Select a suitable range of standard pressure gauge, calibration traceability with National Physical Laboratory or their authorized laboratory.    
4.2    Use comparison test pump to calibrate the pressure gauges.
    4.3    Fix the standard gauge on one side of the comparison test pump and the gauge which is to be calibrated on the other side of the comparison test pump.

4.4    Apply the pressure by rotating the wheel clock wise which is provided on the comparison test pump.  

4.5    Note down the pressures displayed by standard gauge and the gauge which is to  be calibrated at different pressures from minimum to maximum range of the gauge.  Record the readings in the format xxxxx shown in Annexure-I.      
4.6    Acceptance criteria:

The resolution of gauge shall be considered as acceptance criteria for that particular gauge.

?    If the gauge is graduated with 0.1 Kg/cm2 resolution, the acceptance criteria shall be 0.1 Kg/cm2.
?    If the gauge is graduated with 0.2 Kg/cm2 resolution, the acceptance criteria shall be 0.2 Kg/cm2.
?    If the gauge is graduated with 0.5 Kg/cm2 resolution, the acceptance criteria shall be 0.5 Kg/cm2.

4.7    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.
    4.8    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.
    
4.9    Apart from this recalibration, the calibration shall be followed as per regular schedule.

4.10    Calibration tag for pressure 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 with in the acceptable  limit  pink coloured tag shall be   tied  to the gauge).

4.11    Frequency:  Calibration of pressure gauges 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.  
   

Pressure gauges, engineering, particular gauge