7088-8000
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Transducer Spacing
Based on the setup parameters,
TimeGATE
™
automatically calculates the required
transducer spacing. The spacing parameter is displayed in the
SPACING
text box. This
value is for display only and is not editable. Refer to Section 4.2 for more information on
transducer spacing.
F.4.5 CALIBRATION OPTION GROUP
The
CALIBRATION
option group is accessed by clicking on
CALIBRATION
in the Options
Column. To assure accurate flow measurement, the instrument should be properly
calibrated. The calibration methods available are:
!
Zero set calibration
!
Scale factor calibration
These calibration methods must be performed for the particular pipe that is to be metered.
Table F-1 provides guidelines for selecting a calibration method:
Table F-1
Selecting the Calibration Method
Calibration Method Function Application
Zero set calibration
!
Zero flow set
!
Manual zero set
Zeros the instrument for an
actual no flow condition
Applies a manually entered offset
to all flow readings
Installations where flow can be
stopped
Where an offset is required
Scale Factor Compensates for manufacturing
variations in the transducers
Set by the factory to the value
imprinted on the transducers
NOTE:
The 4 to 20 milliampere (4 to 20 mA) current loop can also be calibrated for
applications using a current loop. Refer to Section F.4.8 for more information.
Zero Set Calibration
Once the instrument is operating on the actual pipe to be metered, a small adjustment to the
zero point, or zero set calibration, may be required to maximize accuracy at low flow rates.
Zero set calibration allows the flowmeter to read very close to zero under zero flow
conditions.
There are two zero set calibration methods available: the zero flow set method and the
manual zero set method. The zero point used by the flowmeter in either of these methods is
displayed in a text box to the right of the
ZERO FLOW
command button.
NOTE:
After the instrument has been properly zeroed, it should display a stable reading
well below 0.05 feet per second (0.015 meters per second) under zero flow
conditions with the low flow cutoff disabled.
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