Hach AV9000, User Manual

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• Objects such as rocks, pipe joints, or valve stems create turbulence and generate high-speed
flows near the object. Make sure the area 2 to 4 pipe diameters in front of the sensor installation is
clear of obstructions. Best accuracy is obtained when there are no flow disruptions within 5 to
10 pipe diameters.
• Do not use sites with low-velocity flows that create silt buildup in the invert or channel. Buildup of
silt near the sensor can inhibit the Doppler signal and cause inaccurate sensor readings and depth
measurements.
• Do not use sites with deep rapid flows where sensor installation would be difficult or dangerous.
• Do not use sites with high-velocity, low-depth flows. Splash-over and excessive turbulence around
the sensor can cause inaccurate data.
Interference
The AV9000 interface module includes a sensitive radio-frequency receiver capable of the detecting
very small signals. When connected to a flow logger or sampler communications or auxiliary power
ports, some line-powered equipment can add electrical noise that interferes with Doppler velocity
measurements. Interference with measurements is uncommon in typical sites.
The AV9000 is most sensitive to noise falling within its Doppler analysis span of 1 MHz ± 13.3 kHz.
Noise at other frequencies typically does not cause interference.
Some laptop computers can cause interference problems when operated from external AC power
adapters. If such a device has an effect on the measurements, operate the laptop computer with
batteries or disconnect the cable between the laptop computer and the flow logger or sampler.
Install the AV9000 interface module
The submerged AV sensor connects to a FL series flow logger or AS950 sampler through an
AV9000 interface module. Refer to
Replacement parts and accessories on page 19 to identify the
applicable AV9000 interface module for the flow logger or sampler.
Note: The submerged AV sensor connects directly to Sigma flow meters. An AV9000 interface module is not
necessary.
1. Install the AV9000 interface module. Refer to the AV9000 documentation for instructions.
2. Connect the sensor cable to the AV9000 interface module. Refer to the AV9000 documentation
for instructions.
3. Connect the AV9000 cable to a sensor port (or terminal) on the flow logger or sampler. Refer to
the flow logger or sampler documentation for instructions.
Attach the desiccant hub
Attach the desiccant hub to the flow logger or sampler to give strain relief to the sensor cable and the
connector. Refer to
Figure 3 to Figure 5 .
For the best performance, make sure to install the desiccant container vertically with the end cap
pointed down. Refer to
Figure 3 to Figure 5 .
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