DataGator - Waterford Systems

A Novel and Accurate Flow Metering Technique
for
Open Channel and Full Pipe Flows in Sewers and
Plant Effluent Discharge Pipes
Raj Natarajan
OUTLINE
1.
Introduction
2.
Flow Conditions in Sewer and Effluent
Pipes
3.
Existing Flow Measurement
Technologies and Their Shortcomings
4.
DataGator Flowmeter Design Concept
5.
Laboratory Flow Calibration
6.
System Test and Flow Measurement
Accuracy
7. Conclusions
Flow Conditions in Sewer and Effluent Pipes
Open Channel
___
Free Flow
Submerged Flow
Surcharged Flow
Full Pipe Flow
___
Without Surcharge
With Surcharge
Flow Direction
___
Both Forward and
Reverse
Open Channel – Free Flow
Open Channel – Submerged Flow
(backwater Condition)
Full Pipe Flow
Surcharged Flow
(Flooded Manhole)
Existing Flow Meter Technologies
Full Pipe Flow Only
Orifice Plate / Differential Pressure
Ultrasonic – Doppler Flow Meter
Electromagnetic Flow Meter
(Magmeter)
Vortex Flow Meter
Venturi Tubes
Most Industrial Flow Meters
Open Chennel (Partial Pipe Flow) Only
Flumes
Wiers
Open Channel AND Full Pipe
Area-Velocity Meters
DataGator Flow Meter
Existing Flow Meter Technologies
Flumes (Level Only Meters)
•
•
•
•
Accuracy depends on the level measurement
instrumentation
CANNOT be used for Full Pipe, Surcharged
and/or Reverse flow Conditions
Silt build up at the bottom overestimates flow
Does not work for in-line applications
Existing Flow Meter Technologies
Area Velocity Meters
Principle of Operation: Flow = Velocity X Area
• Can Measure Open Channel Free Flow and Full Pipe Without
Surcharge
• Surcharge Flow Measurements are Inaccurate, If Not Impossible
• Average velocity of the Flow Profile is Arrived at Using A Single
Point Velocity Measurement. Assumptions Used for This
Conversion is NOT True for All Flow Situations. This Causes
Large Errors in Velocity and Hence in Flow
•
To Reduce the Above Problem, an Elaborate In-Situ Calibration
is Required.
U.S. Government Compares Flowmeters
Marsh-McBirney, Inc. Water & Wastes Digest September 1997
A comparison of open channel flowmeter response to one of 50 storm events. These results are
typical of those obtained during extensive testing by the U.S. Government.
This graphic compares magnetic and Doppler velocity sensing techniques using a
a Calibrated Flume as the bench mark for measurement in the open channel flow
condition. The DataGator Flow Metering System uses a calibrated flume/modified
Venturi tube as its primary element for flow measurement.
The only real difference between the DataGator and the U.S. Government bench
mark is that the DataGator yields similar results under all possible flow conditionsopen channel, full pipe, submerged, surcharged and reverse.
NIST traceable accuracy with absolutely no on-site calibration or flow profiling!
Independent Comparison
DataGator Flow Metering System and Velocity/Area Meter
8 inch flow loop
Measurement Technique:
Velocity/Area Meter: Q = V x A
Velocity/Area
DataGator
Meter
Primary sensors:
Level - Pressure transducer
Velocity - Magnetic principle
DataGator Flow Metering System:
Inline Flowmeter
Pressure to flow conversion in a pre-calibrated
flow tube
Primary Sensors:
Three high accuracy pressure transducers
8 inch pre-calibrated flow tube
Performance: (All readings in GPM)
Velocity/Area
Actual
44.7
88.2
102.5
Throat
Transducer
Indicated
151.0
225.0
300.0
DataGator
Actual
44.7
88.2
102.5
Indicated
46.5
89.6
99.8
After repositioning the velocity and level sensors and
calibrating the system (1 hour 15 minutes) using
readings from the inline and DataGator flow meters,
Inlet Transducer
Outlet Transducer
the velocity/area unit did provide accurate readings
under open channel flow conditions. The DataGator
required no calibration or flow profiling.
DataGator FLOWMETER DESIGN CONCEPT
Combination of Two Proven Flow
Measurement Techniques:
Open Channel
___
Flume
Full Pipe
___
Venturi Tubes
DataGator -- Venturi Flume with Patented
Throat Design
• Conventional Venturi Flumes Suffered a
Discontuinity in Flow Measurement at Transition
From Open to Full Pipe Flow
•
DataGator Throat Design Provides a Sill That
Achieves a Simultaneous Filling of the Throat and
the Upstream Pipe. Hence NO DISCONTINUITY
in Flow Measurement at Transition from Open to
Full Pipe Flow.
DataGator Flow Tube Design
DataGator Flow Tube Design
FLOW
DataGator -- OPEN CHANNEL FLOW
This Flowmeter is Designed Such That,
1.The Constriction at the Throat of the Flowmeter is Just Enough to
Cause Critical Depth to Occur at the Throat Region, and
2.A Sill at the Top of the Throat Provides the Condition for
Simultaneous Filling of the Throat and the Upstream Pipe.
Under These Conditions, Open Channel Flow is Given by,
Y1 + (V12 /2g) = Z + Yc + (Vc2 /2g) + hl, and
Q = [ (A23 /T) * g] ½
g
Y1
Yc
Z
A1,A2
T
hl
=
=
=
=
=
=
=
Acceleration Due to Gravity
Inlet Depth of Flow
Throat Depth of Flow
Throat Sill Height
Inlet, Throat Area of Flow
Top Width of Flow in Throat
Head Loss
DataGator -- FULL PIPE FLOW
DataGator Functions Like a Venturi Tube
During Full Pipe Flow. Hence,
Q = [2g (Y1 – Y2)] ½ * A1 / [(A1/ A2)2 –1] ½
Q , the Flow rate, With and Without Surcharge is
Dependent Only on the Differential Pressure
Between Inlet and Outlet.
Flow Tube Calibration Data
University Of Utah Water Research Lab, Logan, Utah
Flow Tube Calibration Data
University Of Utah Water Research Lab, Logan, Utah
DataGator – Flow Data From Customer Site
DataGator – Flow Data From Customer Site
DataGator – Flow Data From Customer Site
DataGator – Flow Data From Customer Site
DataGator – Flow Data From Customer Site
DataGator – Installed in a Manhole
DataGator – Spool Piece installation
DataGator – Spool Piece installation
DataGator – Installations
DataGator – Installations
DataGator – Installations
CONCLUSIONS
1. DataGator Flowmeter Measures Flow
Rate for All Flow Conditions in an
Effluent Pipe or in Sewer Flow
Applications.
2. No In-Situ Calibration Required
3. NIST Traceable Accuracy Readily
Accepted by Wastewater Treatment
Authorities Billing Purposes
4.
CALCUflow Software Generates
Reports and Graphs for Submission to
Authorities.
Other Services Available from Renaissance Instruments
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Installation and start up of DataGator
On-site training
System Integration – Hardware and Software
Inflow and Infiltration studies
Inflow and Infiltration remediation
Recommendations
Implementation Engineering
Consulting Services