Manual – Starflow Ultrasonic Doppler Instrument
Model 6526
Unidata Manual - 6526 Starflow User Manual Issue 17 01 2020.docx
Page 6
2.3.3 Conversion of Logged to Mean Velocity
The logged velocity data may have to be adjusted during post processing to reflect a mean velocity
for the channel. The factors used will be site specific and have to be determined by the operator.
This is done by obtaining a mean channel velocity by conventional techniques and comparing it
with the average logged velocity. If necessary this process should be repeated at various
discharges.
Where the relationship is complex or unstable, the accuracy of this method is compromised.
In laminar flow conditions the channel mean velocity could be expected to be between 90% and
110% of the logged velocity.
In small channels (say a 500mm diameter pipe) the factor may be close to 100% as a
representative area of flow will have been “seen” by Starflow and contributed to the logged
velocity.
In larger channels only the area adjacent to Starflow will be “seen” and the relationship will depend
on how this portion relates to the vertical and horizontal velocity distribution in the channel. An
instrument located in the centre of the stream would normally be in a higher velocity area. However
in a deep channel Starflow may only see the slower portion of the velocity profile.
3.0
SPECIFICATIONS
3.1
Battery Duration Table
12V Battery Capacity
Scan Rate
5 min
1 min*
15 sec
7Ah
130 days
26 days
7 days
12Ah
225 days
44 days
11 days
*Factory setting.
Battery Duration estimates assume battery is fully charged using a modern high quality charger.
Battery self-discharge will be higher at high ambient temperatures, and battery terminal voltage
available will be reduced at low ambient temperatures, which will reduce the above estimates.
These factors should be taken into account when sizing a battery. Where possible, an onsite
recharging system is recommended.
Due allowance must also be made for interrogation by computer/modem.
3.2
Memory Duration Table
Number of Parameters Recorded
Log Interval
15 min*
10 min
Velocity & Depth (2)
300 days
250 days
Velocity, Depth & Temperature (3)
200 days
160 days
Velocity, Depth, Temperature & Battery (4)
150 days
125 days
*Factory setting.
