Flow MeasurementFlow Measurement

byby

Ashfaq Md. AnseryAshfaq Md. Ansery

Flow Measurement

It refers to the ability- to measure the velocity,

volume flow rate or mass flow rate of any liquid or gas

Flow Meter in Real Life

Why it is important? Custody transfer &

Accounting

Performance evaluation

Process control

Research & Development

Flow Meter Selection Factors

Range Accuracy Required Pressure Loss Type of Indication Type of Fluid Calibration Other Factors

Physical size of the meter System pressure cost Operator's skill

Flow Calibration System

Flow Meter Classification Full-bore meter

Operate on all the fluids in the pipe/channel

Insertion meter Do not operate on all fluids

Measure mainly local velocity Use sensing element Small compare to size of the channel

Full-Bore Meter

Venturimeter Orifice meter Flow nozzle and Tubes V-element meters Elbow meters Target meters

-Variable Head Meter

Full-Bore Meter (cont…) Rotameter

-Variable Area Meter Vortex shedding Meter Positive displacement Meter Turbine meter (velocity) Magnetic and Ultrasonic Meter (velocity) Coriolis Meter (mass) Salt Velocity Method (velocity)

Insertion Meter

Pitot tube Current meter and rotating

anemometer Hot wire anemometer Float measurement Photographic and optical method Thermal meters (mass)

Few Definitions

Orifices

Nozzles

Tubes

Jet

Stream issuing from an orifice, nozzle or tube Free jet

Stream of liquid surrounded by a gas and therefore under the influence of gravity

Submerged jet Stream of any fluid surrounded by a fluid

of the same type

Jet Contraction

Coefficient of Contraction, Cc

Cc = A/Ao

A= area of a jet

Ao= area of orifice or other opening

Jet Contraction (cont….)

Coefficient of Velocity, Cv

Cv = V/Vi

Vi = ideal velocity

V = actual average velocity

Jet Contraction (cont….)

Coefficient of Discharge, Cd

Cd = Q/Qi

Qi = ideal rate of discharge

Q = actual rate of discharge

Reference

Chapter 15, Flow Measurement, Page 437-439

Applied Fluid Mechanics (5th Edition)

Robert L. Mott

Reference (cont…)

Chapter 8, Transportation and Metering of Fluids, Page: 214

Unit Operations of Chemical Engineering

(Fifth Edition)

Warren L. McCabe

Julian C. Smith

Peter Harriot

Reference (cont…)

Chapter 12, Fluid Measurements

FLUID MECHANICS with Engineering Applications (SI Metric Addition)

Robert L. Daugherty

Joseph B. Franzini

E. John Finnemore