Flow Meter




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Introduction to Flow Meters and Flow Sensors

Note: Before moving on to the topic of flow meters and flow sensors, you may wish to familiarize yourself with the science of fluid flow by reading this article.

Many industrial applications require a measurement of flow. Sometimes, the flow measurement must be very accurate -- such as in the measurement of material that is used in processes or manufacturing -- so that total amount of raw material can be determined. These types of flow measurements are important when the amount of material being metered is for recipe batches, or when material is loaded or transported and must be measured so it can be paid for. In other applications, such as hydraulic systems on large machines, it's important to determine the amount of fluid flowing in specific parts of a system in order to determine if the valves are working correctly of if a failure has occurred and fluid is being bypassed to the reservoir tank. In some applications the exact amount of flow is not important, and a more general measurement will be enough to indicate if a pump is working, or if a drain line is functioning properly.

A flow sensor or flow meter can be classified as either intrusive or nonintrusive. If a flow meter or flow sensor disturbs the flow of fluid it's measuring, it's classified to be intrusive. If a flow meter or flow sensor does not disturb the flow of fluid it's measuring, it's classified to be nonintrusive.

A flow sensor or flow meter can also be classified by the manner in which it measures flow. e.g., a positive-displacement flow meter is very accurate because it physically measures every drop of fluid, whereas a bypass meter is not as accurate because it measures a small amount of fluid flow and calculates the remainder. Differential flow meters place an obstruction in the path of the fluid flow, such as an orifice plate, and the amount of flow is determined from a calculation based on the amount of pressure drop the fluid has as it moves through the orifice plate. A velocity flow meter measures the velocity of the fluid as it passes the turbine. The fourth way to measure fluid flow is to use a mass flow sensor that calculates the total volume of material that passes through the sensor and determines the flow from this number.

Another way to classify flow meters is to determine how the signal from the sensor will be used. e.g., the signal can be used to determine the amount of flow at any given point in a system and indicate it on a meter or display. Or it can be used to mathematically sum the flow in order to determine the volume of fluid that has passed the sensor in a given time. The flow signal can also be sent to a recording device or a transmitter where it's sent to a control system. In the control system, the sensor signal can be sent to a controller (such as a PLC computer) where it can be compared to a set point. The controller can increase or decrease its output signal based on this comparison. The flow sensor signal can be used to control the system or report the flow for an alarm package that can be set to indicate when the flow is too high or low.

Types of flow meters

Turbine and Paddle Wheel Flow Meters and Flow Switches: Types and How To Select

mechanical engineering schematic symbols: fluid power

Below you will find our top book recommendations for learning the fundamentals of Flow Control in maintenance, engineering and scientific applications.

Flow Control: Passive, Active, and Reactive Flow Management by Mohamed Gad-el-Hak The subject of flow control is broadly introduced in this chapter, leaving much of the details to the subsequent chapters of the book...Flow Control: Passive, Active, and Reactive Flow Management
by Mohamed Gad-el-Hak "The subject of flow control is broadly introduced in this chapter, leaving much of the details to the subsequent chapters of the book..."

Reviews:
" ...very well written with an enjoyable style ...certainly one of the best books this reviewer has read in recent years. It will remain on my closest shelf to be consulted at any moment on any topic it covers." Applied Mechanics Reviews "I would certainly recommend the book, at the very least as a useful source of information. but also as a thought provoking read for all those interested in the field." The Aeronautical Journal Mar 2001 "This is a very interesting book, and a charming one...it is a pleasure to recommend this book to anyone seriously interested in these clever techniques." SIAM Reviews

Product Description:
The ability to actively or passively manipulate a flow field to bring about a desired change is of immense technological and economical importance. This volume provides a thorough, up-to-date treatment of the basics of flow control and control practices that can be used to produce desired effects. The author explores the frontiers of flow control strategies, especially as applied to turbulent flows. Intended for engineering and physics students, researchers, and practitioners, Flow Control brings together in a single source a wealth of state-of-the-art information on this very active field.

Another Review:
concise material for research student on fluid dynamics
the content suits the student who would like to study fluid dynamics in a more specific content. those content are important and critical in fluid. this new book has the quite new field like MEMS, it also has interesting historical note, and mixing. this book is useful

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Flow Control Devices by Yochanan Dvir Flow Control Devices
by Yochanan Dvir

From the Publisher
Few books in the technical literature deal with appliances in * piping systems for fluid supply. This book contributes largely to * this, so important subject. A very wide range of appliances, their * hydraulic and mechanical properties can be found here, together with * some unique and important topics in applied hydraulics, and among * them: the hydraulic interdependence of the throttling device and the * piping system, and its influence on mechanical actuation of the * device. check valve behavior at various flow velocities, and the * consequent sizing of the valve. air flow conditions in an air * valve, as basis for sizing air valve orifice for draining and * filling the piping system. These together with an extensive, clear * description of most of the devices used for flow control, their * performance, installation and maintenance requirements make this * book a must for every water, oil or industrial piping system * designer, manager and operator.

Book Description:
This book deals with devices serving for control of flow in liquid supply and distribution systems, municipal, industrial and agricultural. It describes most of the appliances used in such systems, the various mechanical and hydraulic properties of such devices, and gives useful information on the installation and maintenance required to ensure their proper functioning. The topics dealt with in the book include stop, check, regulation and safety valves, air valves, meters, gauges, filters and joints and also problems in applied hydraulic - water hammer and cavitation.

Excerpted from Flow Control Devices by Y.Dvir. Copyright © 1997. Reprinted by permission. All rights reserved.
From Introduction: Any device installed in a fluid supply system, in order to ensure that the fluid reaches the desired destination, at the proper time, in the required amount (the flow rate), and under the right pressure, is called a control appliance. As such an appliance controls proper operation of a fluid system, selecting its type, size and placement is of uppermost importance and ought to be done with the full knowledge of the various features of the device and with complete understanding of the way it performs. Equally important is proper maintenance in order to ensure faultless and sound performance of the appliance.

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Flow Control by Feedback by Ole M. Aamo, Miroslav Krstic, Ole Morten AamoFlow Control by Feedback
by Ole M. Aamo, Miroslav Krstic, Ole Morten Aamo

Book Info
A comprehensive survey of feedback algorithms for flow control that are currently available. Content structure is ideal for instruction on flow control modules or as supplementary reading on fluid dynamics and infinite dimensional systems courses.

Book Description:
The emergence of flow control as an attractive new field is owed to breakthroughs in MEMS (micro-electromechanical systems) and related technologies. The instrumentation of fluid flows on extremely short length and short time scales requires the practical tool of control algorithms with provable performance guarantees. Dedicated to this problem, Flow Control by Feedback, brings together controller design and fluid mechanics expertise in an exposition of the latest research results. Featuring: Exhaustive treatment of flow control core areas including stabilization and mixing control techniques; self-contained introductory sections on Navier-Stokes equations, linear and nonlinear control and sensors and MEMS to facilitate accessibility to this cross-disciplinary subject; a comprehensive survey of feedback algorithms for flow control that are currently available. In response to the intense interest in flow control, this volume will be an essential addition to the library of researchers and graduate students in control theory, fluid mechanics, mathematics and physics. Content structure is ideal for instruction on flow control modules or as supplementary reading on fluid dynamics and infinite dimensional systems courses.

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