Electromagnetic flowmeter for hydrometric surveys

The new Model 801 Electromagnetic flowmeter from Valeport Instruments is designed for hydrometric survey applications, measuring river, stream or sewer flows

The new Model 801 Electromagnetic flowmeter from Valeport Instruments is designed for hydrometric survey applications, measuring river, stream or sewer flows.

Whilst the unit can be permanently installed, the main application is for portable survey duty, used manually by an operator wading across the flow.

Two styles of solid state sensor head are available, and interchangeable on the same electronics.

A flat sensor is used in shallow streams, which averages the flow within a zone 10mm above the sensor, giving accurate point measurements.

A larger streamlined cylindrical sensor has two sensing electrodes, embedded flush in the side walls, which average the water flow through a zone 120mm diameter around the sensor.

This is particularly useful in turbulent flows, since the averaging over the large zone removes localised disturbances.

Accuracy achievable with both sensors is +/-0.5%, displayed on the electronics unit to 0.001 m/sec.

The electronics unit is battery powered and waterproof, intended for use by the operator using the carrying strap.

The digital display can show measured flow in m/sec or ft/sec, (4 digits) plus the averaging mode and period current, and the standard deviation of the flow within the average.

The operator can programme the data-logger to record up to 999 measurements, date and time stamped, and can configure the sampling and averaging periods to be used.

The sensor height is mechanically adjustable on the graduated wading rod set, which can also be used for water level monitoring.

The data can be downloaded back at the office via an RS 232 link.

The 801 Electromagnetic flowmeter can be used for monitoring fresh or salt water, or waste water/sewage flows.

With no moving parts and a streamlined polyurethane sensor, it is not affected significantly by weed or debris in the flow.

Units have been widely used for Hydrometric surveys and sediment transport studies, by Water and Coastal Authorities, Universities and industry.

Valeport is a manufacturer of a wide range of oceanographic and hydrometric instruments, which also include tide gauges, wave recorders, current meters, water quality instruments, sound velocity probes and customised loggers.

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