Open Channel Flow Measuring

The common method of measuring flow through an open channel is to measure the height or HEAD of the liquid as it passes over an obstruction (a flume or weir) in the channel. Using ultrasonic level technology, The open channel flow meters we offer include a non-contacting sensor mounted above the flume or weir. By measuring the time from transmission of an ultrasonic pulse to receipt of an echo, the water level or "Head" is accurately measured.

Flumes and weirs are specially designed channel shapes that characterize the flow of water. Common types are Rectangular Weirs, V-Notch Weirs, Parshall flumes and Palmer Bowlus flumes. The choice of flume or weir type depends on the application: flow rate, channel shape and solids content of the water.
The open channel flow meters can be calibrated to any flume or weir by menu selection. The flow meter electronics use an internal formula to calculate flow rate (Flow = K Hn, where 'K' and 'n' are constants and 'H' is Head as measured by the instrument). Calibration to uncommon or custom flumes can be done by direct entry of 'K' and 'n' constants.

Sigma model 4.0
A non-contact ultrasonic flow meter that is designed for open channel flow metering, whether you have a flume, weir or any other primary device. This meter comes with a 50,000-point data logger that automatically stores up to 122 days of previous flow data.

Continuously monitor, display, totalize and data log flow through any flume or weir. Model 4.0 includes a non-contacting ultrasonic sensor that mounts just 8" (203.2 mm) above the flowing water. It is accurate (±0.25%) and reliable. There is no obstruction to flow and no fouling. Use the built-in Keypad/menu system to select your flume or weir from the Menu and to choose measurement units (gallons, liters etc.)

The Model 4.0 includes built-in 50,000 point Data Logger and flow reporting system. Retrieve data logs with software – included free with each flow meter. Connect the USB or RS232 output directly to the serial port on your PC or Laptop, or by dial-up connection through modems. Configure the analog output to 0-5V for reduced power consumption.

Use the isolated 4-20mA to transmit flow to remote chart recorders or displays, and the 3 control relays are programmable for level/flow alarm, and flow proportionate pulse (for samplers, chlorinators or remote totalizers). An Intrinsic Safety Barrier is optional for sensor and cable installation in hazardous rated locations. The separate, watertight electronics/display enclosure is mounted at a convenient location within 500 ft (150 m) of the sensor.

Standard features include:

• sensor - Model PZ15, PVC
• sensor cable - 25 ft / 7.6 m RG62AU coaxial
• enclosure - watertight NEMA4X (IP66) polycarbonate
• calibration - to any flume or weir with built-in 3-button programmer, password protected
• displays - Flow/Level values - large 4-digit LCD Totalizer/Menu/Status - 16-digit alphanumeric
• temperature compensation - automatic
• outputs - USB, RS-232C, 0-5V, isolated 4-20mA (1000 ohm)
• data logger - 50,000 point with multi-session and flow report capability
• PC software for data log retrieval by USB, RS232 or by dial-up connection with modems
• 1 PC software utilities disk, USB and RS-232C cables
• 3 relays - programmable flow alarm, flow proportional, failsafe/echo-loss
• electrical surge protection - AC, sensor, 4-20mA - power input
• 100-130VAC 50/60Hz, 6.2 Watts maximum
• 1 Manual - Installation and Operation

Partially full pipe or open channel - Flow Monitoring

A partially full pipe or open channel Flow Meter that 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%.

These Flow Meters work in partially full and surcharged pipes, rectangular, trapezoid and egg-shaped channels.

Monitor flow through open channels, partially full sewer pipes and surcharged pipes without a flume or weir. Ideal for Utilities, storm water, combined effluent, raw sewage, irrigation water and streams.
The model II 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 a pipe or at the bottom of a rectangular, trapezoid or egg-shaped channel. Calibration is simple: enter the pipe diameter or channel width and the meter computes the flow volume and displays the flow rate.
Standard features include:

• sensor – measures flow Velocity and Level
• sensor cable – 25 ft / 7.6 m submersible, shielded 3-coaxial
• enclosure - watertight,IP66 (NEMA4X) polycarbonate
• displays - Flow Rate - large 4-digit LCD
• Totalizer/Menu/Status - 16-digit alphanumeric
• calibration - built-in 3-key programmer
• output – three isolated 4-20mA (1000 ohm), Flow, Level and Velocity
• 2 control relays - 5 amp, SPDT - programmable for flow
• proportional pulse output, flow and/or level alarm
• power input - 100-160VAC 50/60Hz
• electrical surge protection and RFI filters - AC, sensor, 4-20mA
• logger optional
• 1 Manual - Installation and Operation

Portable Level & Velocity Logger

• Logs level, velocity and water temperature in open channels
• Powered by 4 Alkaline D-Cell batteries
• Display - LCD bar graph for level, velocity, temperature, logger and battery capacity
• RS232 , 28,800 Baud output
• Data Logger - 130,000 data point capacity (512K)
• PC software for calculating flow
• Watertight, airtight, dust proof (IP67) polycarbonate enclosure

This compact new meter operates on standard batteries for extended time periods to log level, velocity and water temperature in open channels, partially full sewer pipes, and surcharge pipes without a flume or weir. It is designed for municipal storm water, combined effluent, raw sewage, irrigation water and stream flow.