Averaging Time; Salinity; Table 3:8 - Data Collection Settings - Properties - Xylem SonTek FlowTracker2 User Manual

yellow.
g) To navigate to Template Menu,
i). Press the Left Soft Key.
Properties associated with the parameters in data collection settings are defined in
Table 3:8,
Parameter

Averaging Time

Salinity

Temperature
Sound Speed
Mounting Correction
3.4.2.1 Averaging Time
The Averaging Time parameter specifies the time duration (in seconds) of data
collection during each point velocity measurement.
a) Averaging time is specified in 1-second intervals from 10 to 1000 seconds.
b) The default Averaging Time applied in FlowTracker2 is 40s.
c) To change the Averaging Time,
i). Use the backspace key to clear current entry,
ii). Type in the new value using the keypad.
The averaging time required for single point velocity measurement is usually from 40 to
60 seconds. This however is site dependent and longer averaging times are required
when measuring in turbulent flow conditions.
3.4.2.2 Salinity
The Salinity parameter specifies the salinity value in Practical Salinity Scale
(dimensionless) used to compute sound speed.
a) Salinity is specified in Practical Salinity Scale (PSS-78). Fresh water has a
salinity of 0; seawater salinity generally ranges from 31 to 39 (PSS). The PSS-78
range is 2 to 42 for a temperature range of -2°C to +35°C and hydrostatic
pressure 0 – 10000dBar.
b) The default Salinity applied in FlowTracker2 is 0 (PSS).
Where a measurement location exceeds the PSS-78 range, Salinity cannot be used for
calculation of Sound Speed. Sound Velocimeters must be used to measure the actual
sound speed of the water directly at the measurement location.
c) As a rule of thumb, a 12 (PSS) error in the value of salinity will result in a 1% error
in sound speed, which results in a 2% error in velocity data.
FlowTracker2 User's Manual (January 2019)
Table 3-8 - Data Collection Settings - Properties
Min Max
10 1000
0 42
-5 50
1400 1580
-5 5
Default
40
0
Internal Measured
Internal Calculated
0
44
SonTek – a Xylem brand
Units Required
seconds Yes
PSU Yes
°C or °F Yes
m/s or ft/s Yes
% Yes