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INTRODUCTION

The flow meter demonstration apparatus experiment illustrates the typical methods of flow

measurement of incompressible liquids. This apparatus are able to demonstrate the flow

measurement comparison of different types of condition which are the venture meter, orifice

device and the rotameter.

The accessory is designed to be positioned on the side channels of the hydraulics bench top

channel. The Venturi meter, variable area meter and the orifice plate are installed in a series

configuration to permit direct comparison. Flow through the test section is regulated using a flow

control valve. This together with the bench control valve permits variation of the system static

pressure. Pressure tappings in the circuit are connected to an eight-bank manometer which

incorporates an air inlet/outlet valve in the top manifold with facilities to connect a hand pump.

This enables the levels in the manometer bank to be adjusted to a convenient level to suit thesystem static pressure. The pressure tappings for the manometers are arranged to give a set of

readings around the flow meters in the system. The setup is detailed elsewhere.

Fluid mechanics has developed an analytical discipline from the application of the classical laws

of static, dynamics and thermodynamics, to situation in which fluids can be treated as continuous

media. The particular laws involved are those of conservation of mass; these laws may be

simplified in an attempt to describe quantitatively the behavior of the fluids.

The hydraulic bench service module, F1-10, provides the necessary facilities to support acomprehensive range of hydraulic models each of which is designed to demonstrate a particular

aspect of hydraulic theory.

The specific hydraulic model that is concerned for this experiment is the flow meter test rig (F1-

21). This consists of venture meter, variable area meter, and orifice plate installed in a series of

configurations to allow for direct comparisons.

Orifice

21

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Nozzles

Venturi

Venturi meter

Venturi meter is a tube with constricted throat that increase velocity and decrease

pressure. Venturi meter is used to measure the flowrate of compressible and incompressible

fluid in a pipeline. When a fluid flows through a throat section, which has a smaller cross

sectional area than in a pipe, the velocity of the fluid through a throat is higher than in the pipe. If

velocity higher, pressure will drop. By measuring pressure drop, discharge may be calculated.

Beyond the throat the fluid is decelerated in a pipe of slowly diverging section (sometimes

referred to as a diffuser) in order to recover as much of the kinetic energy as possible. We must

know the principle of Bernoullies equation to understand the principles of venturi meter.

Orifice plate

The orifice meter is also used in measuring the flow rate of a reservoir or through a pipe. The

orifice meter consists of a flat plate with a circular hole drilled in it. There is pressure tap

upstream from the orifice plate and another just downstream.

Variable area meter.

The variable area flowmeter is a simple, reliable, inexpensive, and easy-to-install

flowmeter with low pressure drop and no electrical connection that givesa direct reading of flow

rate for a wide range of liquids and gases.

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-easurement #pparatus $- -/0/% apparatus is designed to operate

together with a basic hydraulic bench or any water to familiari&e the students with

typical methodsof flow measurement of an incompressible fluid.The apparatus is able to

demonstrate the flow measurement comparison by using aventuri meter, orifice meterand -ethod, the flowcomparison can be further

used to compare against the flow measurement of the

hydraulics bench, depending on the type of hydraulics bench in use. (ther features of the flow ap

paratusinclude a 90 degree elbow with pressure tapping before and after this elbow. The purpose

of these features is to provide an added function to this apparatus to allow students to calculate

thetotal head loss and loss coefficient when fluid flows through these devices.2enturi meter

Fig 1.1: Venturi meter

The venturi meter consists of a venturito measure the flow rate of compressible and incompressible fluid in a pipeline. Theventuri tube

has a converging portion, a throat and a diverging portion. The function of theconverging portion

is to increase the velocity of the fluid and lower its static pressure. # pressure

difference between inlet and throat is thus developed, which pressure difference is correlatedwith

the rate of discharge. The diverging cone serves to change the area of the stream bac" to

theentrance area and convert velocity head into pressure head.(rifice meter

Fig 1.2: Orifice meter

consists of a flat plate with a circular hole drilled in it. There is pressure tap upstream from

theorifice plate and another at downstream.3otameter

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OBJECTIVES

To study and compared the operation and the characteristic of three different types of

flow meter which is the venture meter, the rotameter and the orifice.

To obtain the flow rate measurement by utilizing three basic types of flow measuring

technique

To investigate the loss coefficient of fluid through 90 degree elbow.