Aalborg DFM Digital - Manual (Page 16)

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5. OPERATING INSTRUCTIONS
5.1 Preparation and Warm Up
It is assumed that the Digital Mass Flow Meter has been correctly installed and
thoroughly leak tested as described in section 2. Make sure the flow source is OFF.
When applying power to a flow meter within the first two seconds you will see on
the LCD display: the product name, the software version, and revision of the
EEPROM table. After two seconds the LSD display switches to the main screen
with the following information:
= Temperature and Pressure reading (for models DFM 27/37/47 only).
= Mass Flow reading in current engineering units.
= Current Gas Table and Gas Name.
= Totalizer Volume reading in current volume based engineering units.
= Totalizer , Alarm, and Relays status.
DFM Main Screen
Note: Allow the Digital Mass Flow Meter to warm-up for a minimum of
15 minutes.
During initial powering of the DFM transducer, the flow output signal will be indi-
cating a higher than usual output. This is an indication that the DFM transducer
has not yet attained it's minimum operating temperature. This condition will auto-
matically cancel within a few minutes and the transducer should eventually zero.
5.2 Swamping Condition
If a flow of more than 10% above the maximum flow rate of the Mass Flow Meter
is taking place, a condition known as "swamping" may occur. Readings of a
"swamped" meter cannot be assumed to be either accurate or linear. Flow must
be restored to below 110% of maximum meter range. Once flow rates are lowered
to within calibrated range, the swamping condition will end. Operation of the meter
above 110% of maximum calibrated flow may increase recovery time.
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