Mace HVFlo XCi, Руководство по эксплуатации продукта

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diameters. At poor signal sites, turning the sensor around may help to increase signal strengths.
The “
Orientation
” feature allows the user to tell the processing electronics that although the velocities
received are negative (when the sensor is facing downstream), you wish to totalise this flow as positive flow.
NOTE: When receiving data from a sensor facing downstream, the real-time velocity
graph will show a spectrum that appears upside down
Velocity range
This parameter sets the range of expected velocities that are to be analysed. MACE Doppler ultrasonic
sensors “pigeon-hole” velocity readings into 128 positions over the velocity range set by the user. For
example, each “hole” in a range of 0 - 4 m/s is .03125 m/s wide, whereas in a 0 - 1 m/s range each hole is
.0078 m/s wide. For example, in a stream in which the user knows that the peak velocity will never exceed
say, 0.6 m/s a velocity range of 1 m/s may be set. In this way, the resolution of the final average velocity is
increased. In slow moving streams or ones that contain few acoustically reflective particles, a smaller velocity
range will often result in far more repeatable data because the instrument does not waste processing power
gathering data outside of expected ranges. To be safe, the velocity range should be set larger than expected
and the site monitored for several weeks under different flow conditions to determine the peak expected
velocity. After this period, the user may find it prudent to increase the resolution by changing the velocity
range. MACE Doppler velocity sensors calculate an average velocity by measuring the speed of particles
moving through the whole stream cross-section.
In the real-time graph below, the peak velocity (6ft/s) is typically the centre of the pipe whilst the minimum
velocity (0-1ft/s) is typically found along the edges.
WARNING: The velocity range must be set so that ALL components of the stream
velocity are captured when viewed on the “real-time” graph. Failure to do so will
compromise the validity of the velocity calculation.
MACE XCi User Manual - 157 -