general calibration/verification procedure for pressure measuring devices

7/29/2019 General Calibration/verification Procedure for Pressure Measuring Devices

1/5

GENERAL PROCEDURE

FOR

CALIBRATION/VERIFICATION

OF

PRESSURE INSTRUMENT MEASURING DEVICES

22 FEBRUARY 2013


2/5

1

TABLE OF CONTENTS

INSTRUMENTS

PURPOSE AND SCOPE

REQUIRED STANDARD

PREPARATION FOR CALIBRATION

CALIBRATION PROCESS

UNCERTAINTY OF MEASUREMENT


3/5

2

CALIBRATION / VERIFICATION OF PRESSURE MEASURING DEVICES

1.0 INSTRUMENTS

Pressure Gauges, Test Gauges, Pressure Indicator, Pressure Recorders,

Pressure Meters, Pressure Transmitters, Pressure Transducers, Pressure

Calibrators and any related pressure measuring instruments.

2.0 PURPOSE AND SCOPE

The purpose of this procedure is to provide the calibration/verification method

for pressure measuring instruments.

The document reference(s): BS EN 837-1, 3:1998, EURAMET cg-17 version

2.0(03/2011) and In-house calibration procedure, CP-P001 rev. 5.0 and

CP-P003 rev. 3.0

3.0 ENVIRONMENTAL CONDITION

Ambient Temperature and Relative Humidity

The Ambient Temperature and Relative Humidity for this calibration process will

be determined by taking the average of temperature and humidity during

calibration process at start, middle and end of calibration.

4.0 REQUIRED STANDARDS (OR EQUIVALENT EQUIPMENT)

a) Hydraulic / pneumatic Dead-weight Tester

b) Hydraulic / Pneumatic Pressure Calibrator

c) Hydraulic / Pneumatic Pressure Indicator

d) Hydraulic / Pneumatic Standard Test Gauge

e) Hydraulic / Pneumatic Test Comparatorf) Hydraulic / Pneumatic Hand Pump

g) Field Communicator


4/5

3

5.0 PREPARATION FOR CALIBRATION

a) Inspect the Unit under Test (UUT) and clean as required.

b) Ensure UUT is not defective and in good working condition.

c) Ensure Standards (e.g. DWT) is level, filled with sufficient oil and ready

for the calibration. (Note: Normally DWT is recommended used for

calibrating of high accuracy of UUT, such as UUT accuracy better than

or equal 0.25% of full scale).

d) The selections of Standard to be used as appropriate manner by the

operator.

e) Ensure the medium used is correct / compatible to UUT.

f) Connect UUT to the Standards (e.g. DWT) and carried out priming as

necessary.

g) Used glove when handling the Dead-weights for pressure Tester.

6.0 THE CALIBRATION PROCESS

a) Exercise UUT slowly, 3 times form minimum and to maximum and

minimum of the scale.

b) Check UUT over entire the scale from 0% to 100%.Taking the reading

both up and down the scale.

c) Taking readings at uniform intervals along its entire e.g. 0%, 10%, 20%,

40%, 60%, 80% and 100%.

d) Hold at each pressure point a few minutes before noting down values.

e) The reading shall be obtained after the gauge has been lightly tapped.

f) If out of accuracy, release pressure and vent testing apparatus to

ambient pressure before UUT removed, and perform adjustment.

g) For the Test Gauges, with both increasing and decreasing pressure atany point on the scale shall not exceed 0.25%of the maximum scale

value.

h) For normal industrial gauges other than 50 mm diameter, the error of

pressure above 0% and below 90% of the maximum scale value shall

not exceed 1% of the maximum scale value.


5/5

4

i) Close the vent valve; perform a complete calibration by taking the

average of 3 cycles increasing and decreasing pressure readings at

each of the above calibration points.

j) On completion of calibration, release / vent pressure to ambient before

removing UUT.

7.0 UNCERTAINTY OF MEASUREMENT

The uncertainty is at 95% confidence level based on the ISO Guide to the

Expression of Uncertainty in Measurement

general calibration/verification procedure for pressure measuring devices

Documents