In this tutorial we are going to learn about pressure measurement devices. Fluid statics and fluid dynamics form the two constituents of fluid mechanics. Explain the technology options for measuring pressure. An indicating fluid with a density less than water, decreases the range and increases the resolution sensitivity. We will also secure here the various types of devices used for pressure measurement. Record the type and the serial number of measuring devices, and the density of fluid used in them.
Fluid mechanics and hydraulics principles of hydrostatic pressures variation of pressure with depth in a fluid problem 01 variation of pressure. Pressure is the force per unit area acting on a surface. Manometers can be categorized into two types, namely simple manometer and differential manometer. In case of fluid mechanics, we use some specific pressure gauges for measurement of pressure. Basics of fluid flow a fluid is a substance that flows when subjected to a shearing stress layers of the fluid slide relative to each other both gases and liquids are defined as fluids fluid mechanics is the study of the flow of gases and liquids the degree of resistance to shear stress is represented by the term viscosity. The deeper an object in a fluid, the more pressure the fluid exerts on the object. The barometer is a device meant for measuring the local atmospheric pressure. There are two national protocols for validating blood pressure measuring devices. Basic properties of fluids arises when adjacent layers of fluid slip over one another. Fluid statics deals with fluids at rest while fluid dynamics studies fluids in motion. For pressure measurement in hydraulics analysis in civil engineering the knowledge of construction and working of these devices is a must. Using manometers to precisely measure pressure, flow and level.
Their accuracy substantially improved around 1930 when friction effects, drift and elastic. Many devices are based on hydrostatics such as barometers and manometers, i. Manometers are devices used for measuring the pressure at a point in a fluid. Fluid the fluid deforms continuously when subjected to a shear stress. Most pressure measuring devices, however, are calibrated to read zero in the atmosphere, and so they indicate the difference between the absolute pressure and the local atmospheric pressure. Ideal fluid an ideal fluid is one which has no viscosity no surface tension and incompressible 2.
Common device for measuring fluid pressure by christian. Compare the units of the measured data and the data used in calculations. A fluid is a substance that deforms continuously when subjected to a shear stress no matter how small that shear stress may be. Real fluid an real fluid is one which has viscosity surface tension and compressible naturally available all fluids are real fluid. Set the manometer pressure to the atmospheric pressure by opening the upper valve. Today we will understand here the basic concept behind the measurement of pressure at a point in fluid in the subject of fluid mechanics with the help of this post. Fluid mechanics measurements in wind tunnel studies, aeroacoustics, and turbulent mixing layers, the theory of fluid mechanics, the application of the laws of fluid mechanics to measurement techniques, techniques of thermal anemometry, laser velocimetry, volume flow measurement techniques, and fluid mechanics measurement in nonnewtonian fluids. What is principle behind each pressure measurement device and how they operate. Pressure is an important variable in fluid mechanics and many instruments have been devised for its measurement.
Intro to fluid flow dublin institute of technology. Now start the supply at water controlled by the stop valve. Pressure measurement devices inclined manometer, bourdon. Recording the figures and units on the measuring devices as well as factors that affect them. Figure 1 bourdon tube pressure gauge bourdon tubetype pressure sensors are the most common for industrial use in the family of elastic pressure elements. Center of pressure is almost like the location of the resultant force of a system of forces. Viscosity is the property of a fluid which determines its resistance to shearing stresses. Instruments used to measure pressure are called pressure gauges. Density density relates the mass and volume such that mv kg m3 pressure pressure is the result of compacting the molecules of a fluid into a smaller space than it would otherwise occupy. Thus, we conclude that the pressure difference between two points in a constant density fluid is propor. Linear temperature expansion coefficients for aluminum, copper, glass, iron and other common materials. Some of the most commonly used technical terms in fluid mechanics. Fluid mechanics pdf notes fm pdf notes smartzworld. Introduction to pressure in fluid mechanics pressure always acts inward normal to any surface even imaginary surfaces as in a control volume.
Classification of pressure measuring devices mechanical. Request pdf pressure and measuring devices pressure and measuring devices. Pressure measurement helps in determining the liquid level in tanks and. Reynolds number, laminar flow, turbulent flow and energy losses due to friction. Dividing by x and rearranging gives 37 where g s rg is the specific weightof the fluid. Measurement in fluid mechanics also features extensive background materials in system response, measurement uncertainty, signal analysis, optics. Unit 3fluid mechanics pressure measurement pressure scribd. Consequently, any force developed is only due to normal stresses i. Suppose you have a surface s and n number of normal forces are acting on it. What is the pressure, in metric ton per square meter, at 3. When the shear stress disappears the fluid never regain in to original shape.
Fluid mechanics definition of fluid mechanics by the free. Mechanical pressure measurement david gardellin, p. Problem take sea water to be 3% heavier than fresh water and assume it is incompressible. T38 2005 532 dc22 2005014865 isbn 9780521815185 hardback isbn10 0521815185 hardback. This pressure can be measured with various techniques using different types of devices. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Apr 30, 2016 fluid mechanics flow measuring devices created by. Pressure does not depend on the amount of fluid present but the depth of the fluid. Utube manometers can only be used if they are leveled properly. Many devices are based on hydrostatics such as barometers.
Pressure is a normal stress, and hence has dimensions of force per unit area, or. Measurement in fluid mechanics is an introductory, uptodate, general reference in experimental fluid mechanics, describing both classical and stateoftheart methods for flow visualization and for measuring flow rate, pressure, velocity, temperature, concentration, and wall shear stress. Pressure measurement devices such as inclined manometer, bourdon gauge, diaphragm gauge, bellows, pressure transducers, and electronic pressure sensors, are used to measure extreme pressures with high accuracy. Pressure is defined as the normal force exerted by a fluid per unit area of the surface. Further, we will see each type of pressure measuring device in detail. Feb 14, 2017 in this tutorial we are going to learn about pressure measurement devices. Fluid pressure is the force exerted on or by the fluid per unit area. Assuming the concept of center of gravity is known to you, i will try to explain the basics of center of pressure.
Atmospheric,absolute and gauge pressure absolute pressure is zeroreferenced against a perfect vacuum, so it is equal to gauge pressure plus atmospheric pressure. Piezometer sphygmomanometer a device used to measure static liquid pressure. It follows that the shear stresses are everywhere zero in a fluid at rest and in equilibrium, and from this it follows that the pressure that is, force per unit area acting perpendicular to all planes in the fluid is. Some definitions a fluid is any substance which can flow liquids, gases, and plasmas fluid statics studies fluids in equilibrium density, pressure, buoyancy fluid dynamics studies fluids in motion extremely complex topic, just lightly covered density an intensive property of a substance may vary with temperature or pressure a homogenous material has. It is used as primary pressure transducers in many dynamic pressure measuring devices. It is also useful in providing pressure measurement with electrical transducers lvdt. Manometer mercury barometer used to measure atmospheric pressure.
The nature of fluid and the study of fluid mechanics 2. Oct 18, 2014 the diaphragm can be used as a means of isolating the process fluids, or for high pressure applications. The shallower an object in a fluid, the less pressure the fluid exerts on the object. Manometers are used for the measurement of very low pressures as well as vacuum especially. 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. Pressure and pressure measuring devices 53 manometers manometer is a device used to measure pressure at a single or multiple points in a single or multiple pipelines, by balancing the fluid column by the same or another column of fluid. Various types of pressure measuring instrument have been used to measure the pressure intensity at any point in static or moving fluid.
Pressure measuring device authorstream presentation. Selection of pressure gauges depends upon the location and type of fluid flow. Venturi tube due to simplicity and dependability, the venturi tube flowmeter is often used in applications where its necessary with higher turn down rates, or lower pressure drops, than the orifice. May 30, 2015 the actual pressure at a given position is called the absolute pressure, and it is measured relative to absolute vacuum i. Pressure and measuring devices request pdf researchgate.846 559 358 546 535 1091 1536 203 779 758 100 229 1248 674 229 351 655 219 260 514 1498 31 342 794 763 1372 1121 843 1318 274 1448 1073 541 244 801 487 1193 652 969 1257 115 81 1414 1408 1398