Troubleshooting
10.3 Test Facilities Graph Screen
FUS1010 IP65 NEMA 4X & IP66 NEMA 7
168 Operating Instructions, 01/2013, A5E02951520-AC
Transit Time Adjustment: (Hot Key 3)
Observe the short vertical marker at the beginning of the receive signal in the Graph Screen
above. This line represents the position in time (Tn) where the flow meter perceives the
arrival of the ultrasonic signal. There are actually two Tn markers, one for the upstream
arrival time and one for the downstream arrival time. For proper liquid sound velocity
measurement these Tn markers should be positioned near the beginning edge of the receive
waveform envelope (as shown), however, in cases of poor signal conditions it is possible for
this measurement to be off by several receive waveform cycles.
1. To adjust the Tn mark position press the <3> key on the keypad to bring up the [TnSet #]
command.
2. Pressing the <+> or <-> keys will cause the Tn marker to move later or earlier,
respectively. As you adjust the Tn marker, both Tn and Vs (liquid sound velocity) will
change accordingly.
3. To exit this mode, press the <0> key on the keypad.
Zero Crossover Adjustment: (Hot Key 4)
Observe the small "X" mark located on the zero crossing line near the middle of the receive
signal in the Graph Screen above. This "X" indicates the central crossover which the flow
meter is using to measure the transit-time delta. This crossover will generally be close to the
peak of the Receive signal with at least one well formed (non-aberrated) receive cycle on
each side of the crossover.
1. If it appears that the placement of this crossover is unsatisfactory then it can be adjusted
by pressing the <4> key on the keypad, which will invoke the [ZCO Set #] command. The
crossover point can then be moved in either direction on the waveform using the plus <+>
or minus <-> keys. The change from the default value (in receive cycles) will appear in
the number to the right of the command.
2. To exit this mode, press the <0> key.
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