Sigma 911 Intrinsically Safe Portable Area
Velocity Flow Meter
With
quick installation and minimum maintenance, the Sigma 911
Portable Area Velocity Flow Meters ideal for short-term flow studies in
hazardous or potentially hazardous environments. American Sigma´s
advanced Doppler technology is accurate, even in low-flow, full-pipe,
and reversed-flow conditions. There is no need for profiling to
establish accurate average velocity. The Sigma 911 accuracy is further
enhanced by a proprietary technology that corrects for the effects of
temperature and velocity on level measurement.
CSA-NRTL/C certified for operation in Class 1,
Division 1, Groups C & D hazardous locations, DEMKO listed.
Low profile, non-fouling probe reduces your need
for maintenance and is detachable/interchangeable for ultimate
flexibility.
Easy installation with a slender 6.5" in.
diameter and no profiling required. NEMA 6P sealed to withstand
submergence and prolonged surcharge conditions.
Advanced, ultrasonic one-MHz Doppler technology
avoids signal dropouts and ensures, without the need for on-site
calibration, high levels of accuracy in low-flow, full-pipe, or
reversed-flow conditions.
A higher level of accuracy, since the Sigma 911
Portable Area Velocity Flow Meter automatically corrects the effects
of temperature on level measurement.
Patented `Drawdown Correction´ feature corrects
the effects of velocity on accurate level measurement.
Ideal for:
Short Term Flow Studies in Hazardous or
Potentially Hazardous Areas
Sanitary Sewer Evaluation Studies CSO Studies and
Monitoring
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.
Address:
Hach/Marsh-McBirney, 4539
Metropolitan Ct.
Frederick, Maryland
21704 USA
Telephone: U.S. and Canada 1-800-368-2723
Outside the U.S. 1-301-874-5599 - Fax: 1-301-874-8459
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Hach/Marsh-McBirney All rights reserved.
