The municipal and industrial wastewater treatment industries are the largest users of clamp-on ultrasonic flow meters due to the cost effectiveness of the measurement technique. Doppler and transit time instruments are typically used for full pipe flow control throughout a WWT plant. Ultrasonic instruments are also often utilized for open channel flow and level measurements.

Flow Meter is measuring the drain water from a Sludge Press in a 4” PVC pipe.

Flow measurement and totalization is part of this manufacturing company’s waste monitoring process.

This Doppler Flow Meter is measuring pumped grey water discharge from a rural municipality’s septic system.

The flow meter is used to check pump performance and to totalize flow discharge for environmental reporting and state permit requirements.

Our partially full pipes 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%.

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

Sigma Hellas offers for these wastewater measuring applications 2 portable flowmeters, one for full pipes (model IV) and one for partially filled pipes (PFP flow logger).

Model IV: an all-inclusive set suitable for full wastewater pipes ranging from 25 millimeter to 4.50 meter (1 to 177 inches) that measures all conductive or non-conductive containining minimum of 100 microns solids/bubbles. These basic features make the flowmeter very versatile in that it can easily be set in a few minutes. The 50000 points data logger and 30 hours of continuous operation battery life enables reporting and statistics of field work.

PFP flow logger: a portable flow logger for open channels & partially filled pipes limited only by velocity and depth (velocity range 0.03 - 3.03 m/sec, depth range 25.4mm to 4.5m), memory of 130,000 data points and flow derived volumetric flow plotting.

Other models for fixed installation are also available.