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DEVICE DESCRIPTION
2
17
SITRANS FX330
www.siemens.com/flow
05/2016 - A5E36751269-AA
2.2.7 Free air delivery measurement - FAD (optional)
To create compressed air, a compressor draws in air from the ambient atmosphere,
compresses it and delivers it at the required pressure. Since the ambient atmosphere also
contains water vapour, what the compressor draws in is a mixture of air and water vapour. In
addition to the moisture in the air, the ambient temperature and pressure conditions on the inlet
side and the process conditions on the outlet side also influence compressor capacity.
That is why most manufacturers specify compressor capacity as free air delivery at standard
intake conditions. To compare the capacity of different compressors or to compare the capacity
of a compressor at different points in time, the measurement of the air conveyed by the
compressor must be purged of the influences of the process and of the environment and
converted to these standardised suction conditions.
The vortex flowmeter with optional FAD function (FAD - Free Air Delivery) can measure the free
air delivery online, regardless of its function as standard flowmeter. For this the device needs
the process and ambient conditions, as well as the compressor data. When installed on the
outlet side, it measures the air volume generated by the compressor and the process conditions.
The menu-driven, user-friendly software prompts the operator to enter the following values:
•
Ambient temperature (inlet)
•
Atmospheric pressure (inlet)
•
Air humidity (inlet and outlet)
•
Motor speed (rated speed and actual speed)
•
Pressure loss of the air filter
The FAD value is calculated from the measured and entered parameters using the vapour and
compressibility tables stored in the measuring device.
INFORMATION!
FAD measurement is an optional feature which can be unlocked in menu "C6.3 Extras".
Please contact the manufacturer to obtain the four digit code required to enable this feature.
For programming example refer to Settings for free air delivery measurement - FAD on page 83.