Product Components - OTT Flo-Dar Manual Del Usuario

During surcharge (submerged) conditions, a pressure transducer
measures depth. The optional surcharge velocity sensor (SVS) can be
used to measure velocity during surcharge conditions.
Surface velocity measurement
The surface velocity of the water is measured with radar technology. A
radar beam is transmitted from the sensor to the water surface at the
center of the channel. Some of the signal is reflected back at a slightly
different frequency. The difference in frequency, known as the Doppler
frequency, is directly proportional to the speed of the flow. Proprietary
algorithms are then used to calculate the average speed of the flow
stream.
Note: The radar velocity sensor does not operate under surcharge conditions.
Velocity measurements during surcharge
The optional surcharge velocity sensor (SVS) is activated when the flow
level increases to within 17.78 cm (7 in.) of the sensor mounting frame
and stays active until the flow decreases to 17.78 cm (7 in.) below the
sensor mounting frame. The mounting frame is installed 12.7–15.24 cm
(5–6 in.) above the crown of the pipe. This location puts the velocity-
sensing electrodes at the correct location in the flow below the elevation
of the crown of the pipe.
The SVS measures velocity with an electromagnetic sensor that makes
a magnetic field. When the water passes through the magnetic field, a
voltage results that is directly proportional to the speed of the water
passing the sensor.
Depth measurement
The water depth is measured with an ultrasonic pulse echo sensor. An
electronic pulse is sent to the water surface and some of the signal is
reflected back to the sensor. The transit time to the surface and back is
used to calculate the distance from the water surface to the sensor. The
pipe diameter is used to convert the distance to a water depth.
The depth sensor on the Flo-Dar unit can measure distances up to 1.5 m
(5 ft). For larger channels, an extended range sensor is available to
measure up to 6.1 m (20 ft).
During surcharge conditions, a pressure transducer in the Flo-Dar unit is
used to measure the water depth.
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Flow calculations
The velocity and depth measurements are used with the pipe diameter
to identify the flow rate. The flow rate is calculated from the continuity
equation (1):
(1) Flow rate = Average velocity × Area
where
Flow rate = volume of liquid passing the sensor per unit of time (e.g.,
200 gallons per minute)
Average velocity = average velocity of the liquid, calculated with surface
velocity measurements and algorithms
Area = cross-sectional area of the liquid in the channel, calculated with
the channel dimensions and depth measurement

Product components

Make sure that all components have been received. Refer to
and Figure 3. If any items are missing or damaged, contact the
manufacturer or a sales representative immediately.
Figure 2
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