screening technologies-an overview...(electromagnetic, doppler ultrasonic) non-contacting sensor...

Flow MeasurementPresented to: Iowa WEA Operator Training

Presented by: Chris Johnson-Gurney and AssociatesMarshalltown, Iowa

September 10, 2015

Overview

◦ Theory/Computations

◦ Reasons for Measurement

◦ Accuracy vs. Repeatability

◦Methods

◦ Data Collection/Management

Take-Away

◦ “Almost Everything in Flow Measurement is a Compromise”

Theory

◦ How to Compute

◦ Flow = Velocity x Area (Continuity Equation)◦Q = vA

Reasons

◦ Why measure flow?

Operation: Provide information to make process decisions or control another process.

Identify problems (i.e. I&I) (Pre and Post Monitoring)

Regulatory Compliance/Billing

Accuracy vs. Repeatability

Methods

◦ Depth of flow at a known point (pipe, weir, flume, etc.)

◦ Pump-Hours Hours of Pump Run Time x Pumped Flow Rate

Need to know wet well size, control elevations, and time to pump “off” level

Methods

◦ Depth of flow at a known point (pipe, weir, flume, etc.)

◦ Pump-Hours Hours of Pump Run Time x Pumped Flow Rate

Need to know wet well size, control elevations, and time to pump “off” level

Methods (cont’d)

◦ Automatic

Full Pipe

Open Channel

Methods (cont’d)

◦ Automatic

Full Pipe

◦ Magnetic Spool

◦ Insertion Magnetic

◦ Clamp On

Methods (cont’d)

◦Magnetic Spool Advantages◦ Proven Technology◦ Relatively Inexpensive for smaller pipe

diameters

Disadvantages◦ Electrodes Fouled◦ Less Accuracy at Lower Flows

Methods (cont’d)

◦ Insertion Magnetic Advantages◦ Relatively inexpensive over a wide range of

pipe diameters◦ Easy installation/removal for maintenance

Disadvantages◦ Debris hang up in wastewater application◦ Can be less accurate if pipe not profiled

Methods (cont’d)

◦ Clamp On Advantages◦ Relatively inexpensive over a wide range of

pipe diameters◦ Easy installation◦ Can be excellent solution if applied properly

Disadvantages◦ Misapplications have given bad reputation

Methods (cont’d)

◦Open Channel Level with a Primary Device (weir, flume, etc.)◦ Transducer to measure level and

transmitter to compute flow.

Methods (cont’d)

◦ Level with a Primary Device (weir, flume, etc.)◦ Advantages Probably most accurate Can manually measure if electronics fail

◦ Disadvantages Structures can be expensive

Methods (cont’d)

◦ Submerged Sensor (Electromagnetic, Doppler Ultrasonic)

◦ Non-Contacting Sensor (Radar or Laser velocity measurement, ultrasonic level

Methods (cont’d)

◦ Submerged Sensor Advantages◦ Relatively inexpensive◦ Can fit in existing structures, manholes

Disadvantages◦ Debris, grease, etc can foul sensor◦ Access (Manhole/Confined Space Entry)

Methods (cont’d)

◦ Non –Contacting SensorMeasures Level by Ultrasonic and Velocity by Radar

Methods (cont’d)

◦ Non-Contacting Sensor Advantages◦ Non contacting with wastewater flow◦ No confined space entry◦ Retrofit to existing structures◦ Can be removed from grade level

Disadvantages◦ More expensive◦ Additional features required to measure

surcharge flow

Data Collection/Management

Data Collection/Management

Data Collection/Management

◦ Laptop to Data Logger

◦Web Based Data Collection

Considerations

◦ Accuracy vs. Repeatability

◦ Price

◦ Structures

◦ Company Experience

Troubleshooting

◦ Have as much information as possible.

Questions????????

Contact information:Gurney and Associates

4428 South 108th StreetOmaha, NE 68137(402) 551-7995

chrisj@bgagurney.com