The venturimeter is a instrument or device used to measure discharge through a pipe. Just like electromagnetic flow meter, it has no pressure drop head loss hence is very useful in places where pressure drop should be minimal and where a. The venturi meter, also known as venturi tube, belongs to the category of variable head flowmeters. Inserttype venturi flow meter installation and operation manual. Venturi meters are flow measurement instruments which use a converging section of pipe to give an increase in the flow velocity and a corresponding pressure drop from which the flowrate can be deduced. If the velocity at any point decreases, the pressure at that point increases due to the conservation of the kinetic energy into pressure energy. Discharge coefficient performance of venturi, standard. Inserttype venturi flow meter installation and operation manual designs, materials, weights and performance ratings are approximate and subject to change without notice. A schematic of the venturi meter is shown on the diagram at the end of the procedure. Flow through venturi meter background and theory introduction flow meters are used in the industry to measure the volumetric flow rate of fluids. Differential pressure type flow meters head flow metersmeasure flow rate by introducing a constriction in the flow. What is the volumetric flow rate through this meter. This type of a venturi meter is also known as the herschel type and it consists of a smooth gradual contraction from the main pipe size to the throat section, followed by a smooth. The accompanying figure represents the longitudinal view of a venturi meter, a device designed to measure the flow of water in pipes.
Jun 24, 2016 the working of venturimeter is based on the principle of bernoullis equation. There are pressure gauges at the entrance and at the throat, which is 300mm above the entrance. The flow nozzle, like the venturi meter, has a greater flow capacity than the orifice plate and requires a lower initial investment than a venturi tube, but also provides less pressure recovery. This page covers advantages and disadvantages of venturimeter. Venturi flowmeter a practical instrument which makes use of the bernoulli effect and a manometer pressure gauge is the venturi flowmeter. The principle of a venturi meter is depicted in figure 12. After attaching a manometer to help measure the flow rate through the pipe. A venturi meter is also called a venturi flowmeter. Effect of inclination and water cut on venturi pressure drop. The meter consists of a pipe with a narrowing throat that expands back to its original diameter on the other side of the choke point. Its basic principle is also depends on the bernoulli equation i.
A vertical venturi meter measures the flow of oil of specific gravity 0. To find the coefficient of discharge for orifice meter. Differential pressure type flow meters head flow metersmeasure flow rate by introducing a constriction in. The venturi effect is named after its discoverer, giovanni battista venturi. In venturi, pressure energy pe converted into kinetic energy ke to calculate flow rate discharge in a closed pipeline. When the venturi meter is inclined, the potential head changes. The diameter at point 1 is 1 ft, and that at point 2 is 0.
The pressure along the meter is obtained using the 11 pressure taps at the locations shown on the diagram. A jet of water issuing from 5mm diameter orifice working under a head of 2. It works on the basic principle of bernoullis equation. The difference in manometer head is 40 mm of mercury. Consequently, pressure head changes also in a manner such that h is still constant. The orifice, nozzle and venturi flow rate meters use the bernoulli equation to calculate fluid flow rate using pressure difference through obstructions in the flow sponsored links in a flow metering device based on the bernoulli equation the downstream pressure after an obstruction will be lower than the upstream pressure before. Venturimeter principle, construction and working with diagram. For the inclined venturi meter and manometer shown.
Note that it presumes that the density of the flowing gas is constant, which will not necessarily. A venturi tube contains a throat which is smaller in a diameter to the pipeline, into which it fits. Apr 26, 2015 15 venturi meter vs flow when a venturimeter is placed in a pipe carrying the fluid whose flow rate is to be measured, a pressure drop occurs between the entrance and throat of the venturimeter. Construction and specification of venturi meter venturi is an example for restriction type flow meter. Pressure recovery for venturi tubes is a lot better as compared to the orifice plates.
Venturi tubes are appropriate for clean, dirty and viscous liquid and few slurry services as well. Venturi flow meter working principle animation when a venturi flow meter is placed in a pipe carrying the fluid whose flow rate is to be measured, a pressure drop. A venturi meter with a 6 inch throat is placed on a water line that has an 8 inch outer diameter. The venturi flow meter obtains a pressure differential by constricting the flow area and therefore increasing the velocity at the constriction, which creates a lower pressure according to bernoullis theorem. Inclined venturimeter vertical and inclined venturimeter the same formula for discharge as used for horizontal venturimeter holds good in these cases as. Name me two types of venturi meter that you have learnt in this unit. The principle of venture meter is firstly developed by g. This pressure drop is measured using a differential pressure sensor and when calibrated this pressure drop becomes a measure of flow rate. Jan 22, 2018 venturimeter problem example watch more videos at. According to the factory manual the coefficient of discharge is 0.
It is a cheaper device as compared to venturimeter. Pressure measuring devices using liquid columns in vertical or inclined tubes are called manometers. In simplest form, the pitot tube consists of a glass tube, bent at right. It is a device used for measuring the rate of flow of a nonviscous, incompressible fluid in nonrotational and steadystream lined flow. It states that in a steady, ideal flow of an incompressible fluid, the total energy at any point of the fluid is constant. They have been in common use for many years, especially in the water supply industry. For an inclined manometer to be a primary device, the inclined tube must be straight and uniform. Venturi flow meter installation and operation manual designs, materials, weights and performance ratings are approximate and subject to change without notice. As the fluid proceeds further into the converging section, its pressure reduces gradually and it finally reaches a value of p2 at the end of the converging section and enter the cylindrical section. The reading of manometer h m is employed to get h, as discussed before. A major disadvantage of the venturi nozzle is that it is more difficult to replace than the orifice unless it can be removed as part of a spool section. Fluid mechanics module 4 venturi meter lecture 28 youtube.
Advantages of venturimeter disadvantages of venturimeter. Subject fluid mechanics topic module 4 venturi meter lecture 28 faculty venugopal sharma gate academy plus is an effort to initiate free online digital resources for the first time. Jun 05, 2018 venturi meter is a device used to measure the flow rate or discharge of fluid through a pipe. The concentric orifice plate flow meter reduces the pressure by forcing the fluid through a thin plated circular opening. Department of mechanical engineering venturi meter.
Horizontal venturi meter and inclined venturi meter. Venturi meterconstruction, working, equation, application. Energy losses through venturi, orifice, and rotameter. In venturi tubes, pressure loss is low and viscosity effect is high. The fluid flows inside the inlet section of the venturi meter having a pressure p1. It is used to calculate the velocity of fluids in running through a pipeline. The venturi meter is invented by an american engineer clemans herchel 18411932 and named him after italian giovanni venturi 18421932. The cross section of the throat is much less than the cross section of the converging and diverging parts. An intelligent flow measuring technique using venturi. A venturimeter is fitted in a pipe of 30 cm diameter inclined at 40 to the horizontal to measure the flow rate of petrol having a specific gravity of 0. The inclined manometer is frequently called a draft gage because it is widely used for determining the overfired draft in boiler uptakes and flues. The total energy consists of pressure energy, kinetic energy and potential energy or datum energy.
To find the water flow rate using the venturi meter and the pressure distribution along the meter. The classical venturi meter, whose use is described in iso. Fluid mechanics 91a1 definitions fluids substances in either the liquid or gas phase cannot support shear. Jul 23, 2018 subject fluid mechanics topic module 4 venturi meter lecture 28 faculty venugopal sharma gate academy plus is an effort to initiate free online digital resources for the first time. In 3 calibration of flow meter is done with the help of microcontrollers. This study presents an experimental investigation of pressure drop measurements in a tercom flanged machined venturi meter of 0. Inserttype venturi flow meter installation and operation. In principle the constriction could be an abrupt change of crosssection, but it is better to use a more gradual constriction and an even more gradual return to the full flow area following the constriction. One of the most common is the water filled utube manometer used to measure pressure difference in pitot or orifices located in the airflow in air handling or ventilation system.
The manometer measures a differential pressure of 5 inches of mercury. A venturi meter is basically a type of flow meter with a specially designed tube, used to measure the flow velocity of liquids especially highly viscous liquids. For the inclined venturi meter and manometer shown above, determine the difference in pressure between points a and t i. As the fluid enters in the throat, its velocity increases and pressure decreases. It is one of the most accurate means of measuring the flow. Venturi flow meter installation and operation manual. Problem the accompanying figure represents the longitudinal view of a venturi meter, a device designed to measure the flow of water in pipes.
Discharge coefficient performance of venturi, standard concentric orifice plate, vcone, and wedge flow meters at small reynolds numbers colter l. In practise the venturi tube is used in planes to measure the flight velocity. The ratio of areas of main pipe and throat is 5 and the throat is at 1 m from the inlet along its length. The inlet diameter equals d 26 mm and the throat diameter d 16 mm. Fluid mechanics pdf notes fm pdf notes smartzworld. Such a device is called a venturi meter since it relies on the venturi effect. The restriction diameter should not be less than 0. It consists of flat circular plate which has a circular hole, in concentric with the pipe. This also work on the same principle as that of venturimeter. It mentions venturimeter advantages or benefits and venturimeter disadvantages or drawbacks. The venturi flow meter consists of a streamlined contraction and a streamline expansion as shown the diagram. Fm 308 flow measurement by venturi and orifice meter. Inclined venturimeter vertical and inclined venturimeter the same formula for discharge as used for horizontal.
Venturimeter is an application of bernoullis equation. In simple language, this is defined as the sum of pressure energy, kinetic energy per unit volume and potential energy per unit volume equal in the same. Department of mechanical engineering venturi meter objective. Introduction to dimensions and units physical properties of fluids specific gravity, viscosity, surface tension, vapor pressure and their influences on fluid motion pressure at a point, pascals law, hydrostatic law. Effect of inclination and water cut on venturi pressure. Venturi flow meter working principle animation when a venturi flow meter is placed in a pipe carrying the fluid whose flow rate is to be measured, a pressure drop occurs between the entrance and throat of the venturi meter. Energy losses through venturi, orifice, and rotameter flowmeters. Venturi meter is a device or component which is used for measuring the rate of flow of liquid through pipes. Venturi meter is a device used to measure the flow rate or discharge of fluid through a pipe.
The venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section or choke of a pipe. Fm 308 flow measurement by venturi and orifice meter objectives. It is that portion of the venturi where the fluid gets converges. The illustration shows that you can express the fluid velocity v 1 at the inlet of the device in terms of the difference in pressure measured by the manometer. Venturimeter principle, construction and working with. May 28, 2014 a venturi meter with a 6 inch throat is placed on a water line that has an 8 inch outer diameter. To find the coefficient of discharge for venturi meter. Venturi meter and orifice meter are the commonly used flow meters for measuring massvolumetric flow rate or velocity of the flowing fluid. It is the portion that lies in between the converging and diverging part of the venturi. The venturi flow meter obtains a pressure differential by constricting the flow area and therefore increasing the velocity at the constriction, which creates a.
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