Hach AV9000, User Manual

Page: 7 / 138

A pressure transducer in the sensor converts the pressure of the water to a level measurement. The
level measurement and the user-entered channel geometry are used to calculate the wetted area of
the flow stream.
The sensor also contains two ultrasonic transducers: one is a transmitter and the other is a receiver.
A 1 MHz signal is transmitted and reflected off of particles in the flow stream. The reflected signal is
received and its frequency is offset by the Doppler shift proportional to the velocity of the particles in
the flow stream. The flow logger converts the doppler shift in the returned ultrasound signals to a
velocity measurement.
Product components
Figure 2 shows the items in the shipment package. Contact the manufacturer if any components are
damaged or missing.
Figure 2 Product components
1 Submerged AV sensor 3 Junction box
2 Submerged AV sensor with junction box 4 Mounting screws (6x)
Installation
Installation guidelines
D A N G E R
Explosion Hazard. The non-IS AV sensors (770xx-xxx P/Ns) are not rated for use in classified Hazardous
Locations. For classified Hazardous Locations, use IS AV sensors (880xx-xxx PNs) installed per the control
drawings in 911/940 IS Blind Flow Meter manuals.
D A N G E R
Potential confined space hazards. Only qualified personnel should conduct the tasks described in this section of
the manual.
• Do not install more than one sensor in pipes with a diameter of less than 61 cm (24 inches).
Multiple sensors in smaller pipes can create turbulent or accelerated flows near the sensors, which
may cause inaccurate measurements.
• Mount the sensor as close as possible to the bottom of the pipe invert. This will give the most
accurate low-velocity-level measurements.
• Do not monitor flows in the manhole invert. The best location for the sensor is 3 to 5 times the
sewer diameter/height upstream of the invert.
• Put monitoring sites as far from inflow junctions as possible to avoid interference caused by
combined flows.
English 7