SIGMA 930

Open Channel
Flowmeters

SIGMA 930 Long-Term Area Velocity Flow Meter

The Sigma 930 Long-Term Area Velocity Flow Meter - our most advanced flow meter - supports three interchangeable sensors, long battery life, and increased data storage, and offers optional interfaces with samplers and modem capability.

The Sigma 930 Long-Term Area Velocity Flow Meter is designed for long-term/permanent flow studies with approximately 365-day battery life and a strong NEMA 6P PVC enclosure. Permanent collection system monitoring can now be done confidently, within an affordable budget.

	Multi-point and/or redundant monitoring with a single meter.
	Up to three level and velocity sensors.
	Low power draw creates an extended year-long battery life.
	Optional rainfall logging feature records and characterizes rain events, a true innovation in water monitoring.
	Optional internal modem automates data retrieval, paging and reporting.
	Optional sampler pacing capabilities, ideal for CSO and Storm-water.
	NEMA 6P sealed to withstand submergence and prolonged surcharge conditions.
	Advanced, ultrasonic one-MHz Doppler technology avoids signal dropouts and ensures high levels of accuracy in low-flow, full-pipe or reversed-flow conditions, without the need for on-site calibration.
	A higher level of accuracy, since the 930 automatically corrects the effects of temperature on level measurement.
	Patented drawdown correction feature corrects the effects of velocity on accurate level measurement. Multiple sensors for redundancy, averaging and multiple pipe monitoring.

Ideal for:

	Long-Term Flow Monitoring Sanitary
	Sewer Evaluation Studies
	CSO Studies and Monitoring
	NPDES Storm-water Compliance
	Permanent Collection System Monitoring

Sigma 930T Remote Communications Flow Meter
The New Sigma 930T Remote Communications Flow Meter provides a single supplier solution for the collection and integration of information throughout a waste water collection system.

Ideal for continuous, real-time access to data in remote locations

The New Sigma 930T Remote Communications Flow Meter offers all the advance features of the Sigma 930 Long-Term Area Velocity Flow Meter with additional features:

	Six communications options available: Local RS232, Landline Telephone, Wireless CDMA, 1 XRTT, GSM,
	Automatic Data Retrieval
	Alarm Notification and Alarm Forwarding Management
	Secure Data Transmission
	Telogers for Windows software that performs automatic communications, including Call Scheduling and Information Management

Sigma's Patented Drawdown Correction and the Bernoulli Principle:
The Bernoulli Principle states that as the velocity of a fluid increases, its pressure decreases. The Bernoulli Principle simply describes the relationship between the velocity of a fluid and its pressure. If a measurement of the pressure of the moving fluid is taken at a point just forward of the front edge of the shape, and another measurement is taken at the apex, of the upper curved surface, one would notice that the pressure at the apex is lower than the pressure at the leading edge. It is this same principle that is responsible for the lift on an airplane wing. Level measurement using a submerged depth sensor is similarly affected by increases in fluid velocity.

As the velocity of water increases past the probe.
A drop in pressure (vacuum) is induced near the pressure sensor (level) port located at the sides of the probe.
This results in the lowering of the indicated level (or pressure) sensed at the port.
Sigma's patented "Drawdown Correction" software adjusts the level readings for this effect. Sigma's patented drawdown correction adjusts for these effects through software. The software correction algorithms are based on flow data collected during extensive laboratory and real life testing.

This testing resulted in US patent # US5691914:
Fluid flow measurement correcting system, and methods of constructing and utilizing the same. Abstract: "An apparatus for calculating fluid flow in a channel, comprising a probe member which detects fluid depth in the channel; a mechanism for measuring average fluid velocity in the channel; a mechanism for correcting the detected fluid depth based upon the measured average fluid velocity in order to account for drawdown; and a mechanism for calculating average flow rate based upon the average fluid velocity measurement and the corrected fluid depth value."

*Daniel Bernoulli (1700-1782): Swiss mathematician, son of Johann Bernoulli, who showed that as the velocity of a fluid increases, the pressure decreases, a statement known as the Bernoulli Principle. He won the annual prize of the French Academy ten times for work on vibrating strings, ocean tides, and the Kinetic Theory of gases. His Kinetic Theory proposed that the properties of a gas could be explained by the motions of its particles. He was the first person to encounter the functions today known as Bessel Functions.

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