CALIBERATION OF PRESSURE GAUGES

1. PURPOSE

To established a procedure for the calibration of pressure gauges.

2. SCOPE

This procedure covers all pressure gauges being calibrated by Siza personal.

3. EQUIPMENT USED

Calibrated Pressure Gauge.
Compressed Air System.

4 PROCEDURE

The Pressure gauge is handled in the following way.

Not down all relevant information of instrument in the data sheet.
Now clean the gauge for any stain or rust.
Check the zero error of the gauge; adjust if required with the help of needle puller.
Now install the gauge on the air system (compressor) with care so that there is no leakage of Air.
Now check the gauge mechanism by applying pressure from regulator equal to half value of full scale of the gauge.
The gauge is to be calibrated on four approximately or equally distributed points on the full scale i.e.
25% of full scale
50% of full scale
75% of full scale
100% of full scale
Note down the pressure reading of first set point in the column marked ‘SET VALUE”.
Now increase the pressure from regulator so that the under calibration gauge reads first set point value. Note the said reading in the column marked “READ VALUE” in the data sheet.
Note down the reading on the standard instrument in the column marked “TRUE VALUE in the data sheet.
Repeat steps vii, viii and ix for 50% 75% and 100% and note the readings in the respective columns in the data sheet.
Calculate the deviation by subtracting the True Value from the Read value, and enter the deviation in the column in the data sheet.
Now analyze the deviation. If the deviation is out of the specified deviation of the gauge is to be adjusted until the deviation comes within required deviation. If after adjustment deviation does not come within specified deviation stop calibration and replace the instrument with new one and calibrate it again and fill the final inspection sheet accordingly.
If the deviation within specified deviation affix the calibration sticker on the gauge and submit the data sheet.
Calibration engineer prepare the calibration sheet and submit to Maintenance Manager.
The record sheet is sign by concern calibration Engineer.