Area-Velocity Flow Monitor/Flow (open channel)/Greyline

Monitor flow through open channels, partially full sewer pipes and surcharged pipes without a flume or weir. Ideal for municipal stormwater, combined effluent, raw sewage and irrigation water.

Uses a submerged ultrasonic sensor to continuously measure both Velocity and Level in the channel. The sensor is a completely sealed ultrasonic unit with no orifices or ports. It mounts inside the pipe or at the bottom of a rectangular channel. No special compounds, tools or hardware are required. The AVFM sensor is tolerant of turbulence and high approach velocity.

How it works... Area-Velocity Flow Measurement
An Area-Velocity Flow Meter continuously measures both Level and Velocity to calculate flow volume in an open channel or pipe.
The ultrasonic sensor is installed at the bottom of a pipe or channel. To measure water level the sensor transmits ultrasonic pulses that travel through the water and reflect off the liquid surface. The instrument precisely measures the time it takes for echoes to return to the sensor. Based on the speed of sound in water, the level is measured with accuracy of ±0.25%. Flow velocity is measured with an ultrasonic Doppler signal continuously injected into the water. This high frequency sound (640 KHz) is reflected back to the sensor from particles or bubbles suspended in the liquid. If the fluid is in motion, the echoes return at an altered frequency proportionate to flow velocity. With this technique the instrument measures flow velocity with accuracy of ±2%. Greyline Area-Velocity Flow Meters work in partially full and surcharged pipes, rectangular, trapezoid and egg-shaped channels.
A separate down-looking ultrasonic sensor can be used for highly aerated or turbulent flow applications. It measures level by transmitting ultrasonic pulses through the air to the liquid surface with accuracy of ±0.25%. Along with the level sensor, a submerged Doppler velocity sensor is used to measure the water velocity.

Standard features include:

sensor - Model QZ-A, PVC, measures flow velocity and level
sensor cable - 25 ft / 7.6 m submersible, shielded 3-coaxial
enclosure - watertight NEMA4X (IP66) polycarbonate
displays - Flow/Level values - large 4-digit LCD
Totalizer/Menu/Status - 16-digit alphanumeric
calibration - built-in 3-key programmer
temperature compensation - automatic
output - two isolated 4-20mA (1000 ohm), programmable for Level, Velocity or Flow
3 control relays - 5 amp SPDT - programmable for level alarm, flow alarm or flow proportional pulse
power input - 100-130VAC 50/60Hz, 7.5 watts maximum
electrical surge protection - AC, sensor, 4-20mA
1 Manual - Installation and Operation

AREA-VELOCITY FLOW MONITOR SPECIFICATIONS

SCOPE: This specification covers an ultrasonic, area-velocity flow monitor as manufactured by Greyline Instruments, Massena, New York / Long Sault, Ontario. The instrument shall provide for indicating, transmitting, totalizing of the flow rate through rectangular or trapezoidal channels and partially filled or surcharged round pipes.

A. GENERAL

Flow Monitor to consist of a submersible ultrasonic sensor, connecting cable, and a remote enclosure with indicating, transmitting and controlling electronics. System shall have no moving parts.
Level measurement accuracy shall be ±0.25% of Range. Velocity measurement accuracy shall be ±2% of reading.

B. SENSING ELEMENT

Ultrasonic sensor shall be designed for continuous submersion in liquids.
Using the Doppler principle, the sensor shall measure fluid velocities from 0.1 to 20 ft/sec (0.03 to 6.2 m/sec).
Using ultrasonic echo-ranging principle, the submerged sensor shall measure liquid level from 1" to 15 ft. (25.4 mm to 4.57 m) above the sensor. Minimum range or deadband shall not be greater than 1" (25.4 mm). Level sensing circuitry shall include a temperature sensor for automatic temperature compensation.
Sensor shall be constructed of PVC.
Sensor operating temperature shall be from 5°F to 150°F (-15°C to 65°C).

C. SENSOR CONNECTING CABLE

Provide minimum length 25 ft (7.6 m) tri-coaxial cable with potted bond to the Sensor head. Sensor cable shall be waterproof and electrically shielded. Exposed material shall be polyurethane only.
Extended sensor cable shall be shielded tri-coaxial to a maximum length of 500 ft (152m). Cable shall be spliced with screw terminal connections in manufacturers recommended steel NEMA4 Junction Box.

D. TRANSMITTER

The transmitter shall provide for field calibration to rectangular channels, trapezoidal channels and round pipes.
Calibration shall be via built-in 3-key calibration system with menu selection of parameters. Systems requiring calibration by Parameter codes, BCD switches or external calibrators shall not be accepted.
Calibration data shall be password protected and permanently stored through power interruptions for a minimum of 12 months.
Field calibration shall allow selection and automatic conversion of measurement units, measurement span, high/low flow alarm relay and flow proportional relay pulse rates.
Transmitter shall permit field programmable damping to smooth output in turbulent flow conditions, and programmable rejection time to disregard false signals from rain, wind, floating objects and spurious echoes.
Transmitter operating temperature shall be from -5° to 140°F (-20° to 60°C). Transmitter shall contain a thermostat-controlled enclosure heater for condensation protection below 30°F (-1°C).
Transmitter shall have two isolated 4-20mA outputs rated for 1000 ohm maximum load. Outputs shall be user-configurable for level, velocity or flow.
Provide 3 relay contacts rated 5 amp SPDT programmable to operate a remote totalizer, a sampler, high-low flow alarm plus echo loss alarm.
Provide a 4-digit LCD display scaled in user-selected engineering units and visible without opening the Transmitter enclosure.
Provide a 16-digit alphanumeric display for calibration menu, running totalizer, flow reports, or error message display of echo loss or other fault conditions.
Transmitter shall be housed in a wall-mount, watertight NEMA4X (IP66) enclosure with hinged, clear cover. Mounting hardware shall be included.
Transmitter Displays indicating flow rate, units of calibration, maximum flow rate and flow totalizer shall be visible without opening cover.
Transmitter electronics shall be surge protected on AC power input, sensor and 4-20 mA outputs.
Transmitter power input shall be 115VAC 50/60Hz with power consumption of 7.5 watts or less.

E. OPTIONAL FEATURES FOR INSERTION AS REQUIRED

Sensors

Have separate, submerged Doppler velocity sensor, plus a non-contacting ultrasonic level sensor mounted above the liquid. Doppler velocity sensor shall be designed for continuous submersion in liquids and rated for fluid velocities from 0.1 to 20 ft/sec (0.03 to 6.2 m/sec). Non-contacting ultrasonic level sensor shall be rated for measurement range from 8" to 12 ft. (203.2 mm to 3.66 m) and shall include integral temperature compensation.
Sensor cable shall be 50 ft. (15 m) continuous length with potted bond to the Sensor head. Extended sensor cable shall be shielded tri-coaxial to a maximum length of 500 ft (152m). Cable shall be spliced with screw terminal connections in manufacturers recommended steel NEMA4 Junction Box.
Sensor shall mount with manufacturer's stainless steel mounting band for specified pipe diameter from 6" to 38" (150 to 975 mm).

Electronics

Have a built-in 50,000 point data logger, RS232C serial output and connecting cables. Data logger shall support time and date-stamped logging and generate formatted flow reports including total, average, minimum, maximum and times of occurrence. Include Windows software for data log retrieval, graphing and export.
Electronics enclosure shall include Intrinsic Safety Barriers. Sensor, connecting cable and junction boxes shall be rated intrinsically safe to Class I,II,III, Div. I,II, Groups C,D,E,F,G.
Have a thermostat controlled enclosure heater for Transmitter operation at temperatures below freezing.
Have manufacturer's recommended enclosure sunscreen to permit Electronics enclosure mounting in direct sunlight.
Transmitter power input shall be 200-260VAC 50/60Hz with maximum power consumption of 7.5 watts or less.
Transmitter power input shall be 24VDC with maximum power consumption of 7.5 watts or less.
Transmitter power input shall be 12VDC with maximum power consumption of 7.5 watts or less.

F. MANUFACTURER

Area-Velocity Flow Monitor shall be Greyline Model AVFM and warranted against defects in materials and workmanship for one year.