Calibration of Ultrasonic Flowmeter
Calibration of Ultrasonic Flow meter
To ensure the fair gas transaction at custody transfer
locations, pipeline companies are looking towards the credibility
and excellence of meter calibration as the main parameter to ensure
the reliability of the gas.BACKGROUND
Thecalibrationlaboratoriesusetheirownpressure
andtemperaturetransmittersinordertoconformto
theiraccreditedprocedures.The calibration must be done under
conditions representative of the actual operation of the flow
meter.The calibration must be performed by a certified and
traceable laboratory.
Flow meter installed at a Calibration Facility
Flow meter is installed correctly with respect to flow direction
and orientation.Same output signal is used during calibration as
will be used in the final installation for traceability
purpose.
Before Calibration Start
The calibration process begins with the highest flow rate. The
flow of the facility is slowly increased until the high flow rate
is established. The stability of the systems is allowed to
stabilize before any data is sampled. The facilities acquisition
system provides stability indicators. This information can be
reviewed both graphically and in a tabular format.
Data recorded during the calibration sampling period
includes:Pressures, Temperatures, Flow rates,Gas composition.
Acquiring ultrasonic flow meter performance data (log or
maintenance file) via the instrument manufacturers software.The
historical data can be used to qualify the instrument output and
performance in the field where a reference standard is not
accessible.
After the calibration process has been completed for all
requested flow points, an as-found calibration error curve can be
produced and adjustment factors can be determined.CALIBRATION
ADJUSTMENT AND VERIFICATION
Adjustment factor is calculated and entered into the meter
configuration for every flow rate tested.
ACFH actual cubic feet per hourAGA American Gas
Association10
Selecting and applying the proper flow meter for a given job
requires effective cooperation between flow meter users,
manufacturers and calibration facilities. Summary
They must be calibrated as close as possible to the actual
conditions of use and proper compensations should be applied for
any deviations from ideal conditions. The accuracy requirements for
the intended measurement must be defined based on the needs of the
application. It must be confirmed that the flow meter is calibrated
by a laboratory which is capable of producing calibrations with
such precision. Care should be taken to insure that at the time of
use, the flow meter possesses a valid calibration according to the
guidelines.Requirements for proper calibration and use of flow
meters
