An orifice plate is a thin plate with a hole in it, which is usually placed in a pipe. An orifice plate is basically a thin plate with a hole in the middle. Discharge coefficients of squareedged orifices for. In consequence, they account for almost 50% of the instruments used in. The point where the fluid flow profile constricts to a minimum crosssectional area after flowing through the orifice is called the vena contracta, and it is the area of minimum fluid pressure. Handbook of chemical hazard analysis, appendix b click on pdf icon, wait and then scroll down to page 394 of 520 pdf pages. 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.
This pressure drop is linear and is in direct proportion to the flowrate of the liquid or gas. It mainly consists of an orifice plate, an orifice plate housing, and a meter tube. Orifice plates according to din en iso 5167 2 standard concentric orifice plate figure 1. Technical note 12, differential pressure mass flow meter, rev. In order to use any of these devices for measurement it is necessary to empirically calibrate them. It is usually placed in a pipe in which fluid flows. The principle of the orifice meter is identical with that of the venturi meter. The orifice meter consists of a flat orifice plate with a circular hole drilled in it. Inserting the higher discharge coefficient value of 0. Introduction to the theory of plates stanford university. So, now i may apply bernoullis equation to, again, a fluid conduit, but now i have a restriction in it.
Orifice plates cover a wide range of applications of fluid and operating conditions. It is known that if severe cavitation occurs at piping in which the restriction orifice is installed, the trouble such. This is the theory behind and orifice plate and venturi. It is mainly used for robust applications as it is known for its durability and is very economical. Orifice plates are simple, cheap, and available in a wide range of sizes. To find the coefficient of discharge for orifice meter. Pdf the impact of the orifice plate deformation on the differential. This is usually done by chamfering at an angle of approximately 45 degrees at the edge of the orifice so that the edge is as narrow as possible, keeping the resistance of the plate. The orifice plate is an essential component used to generate a specific, predictable pressure drop in the system. Pdf this work aims to determine the impact of orifice plate deformation on the differential pressure at the highpressure natural gas pipelines.
Pdf flow through an orifice rajkumarsingh mondatta. Restriction orifice plates and critical flow devices their calculation, construction and application for pressure control and flow limitation flow measurement of liquid, gas and steam according to the differential pressure principle has been a recognized principle for many years using orifice plates, venturi tubes and flow nozzles. To calculate the flowrate of a fluid passing through an orifice plate, enter the parameters below. Restriction orifice plate program restriction orifice program is specially designed to assist engineers for limiting the flow which is the intended purpose of reducing the flowing pressure or the rate of flow. The bore of the orifice plate is a semicircle to perform the same function as the eccentric orifice plate. Differential pressure type flow meters head flow metersmeasure flow rate by introducing a constriction in the flow. Flange taps or vena contracta taps are employed to take out fluid pressures. Squareedged orifice plates may be installed in either direction, since the orifice plate appears exactly the same from either direction of fluid approach. An orifice meter is basically a type of flow meter used to measure the rate of flow of liquid or gas, especially steam, using the differential pressure measurement principle.
Plates can be configured as recessed, pressed, or pressed with tab to identify size without breaking the union. The traditional orifice flow meter is a thin circular plate with a tab for handling and for data, inserted into the pipeline between the two flanges of an orifice union. Acoustic absorption characteristics of an orifice with a mean. Differential pressures are taken out in a corner tap system. Aug 28, 2009 this is the theory behind and orifice plate and venturi. This obstruction creates a difference in the static pressure between the upstream and downstream side of the device.
The anechoic termination assured that the measured impedance was due to the orifice and surrounding plate alone. The most commonly used inferential or rate meter is the thin plate, concentric orifice meter which is the primary device discussed in this paper. Balch division of mechanics and computation department of mecanical engineering stanford university stretching and bending of plates fundamentals introduction a plate is a structural element which is thin and. The orifice plate is a metal disc with a concentric hole in it, which is inserted into the pipe carrying the flowing fluid. Basics of the orifice plate flow meter custom search as discussed in flow instrumentation. Ateachorificethetemperature and static pressurewereobserved, and the fall of pressurethroughthe orifice was measuredbetween pairsof taps locatedin each of the three wayscommonly. This method of installation is costeffective, but it calls for a process shutdown whenever the plate is removed for maintenance or inspection. Metger lewis research center cleveland, ohio national aeronautics and space administration washington, d. Pdf orifice plate sizing calculation using a new labview. Increase in velocity due to reduced cross section results in reduced pressure.
A nozzle, venturi or thin sharp edged orifice can be used as the flow restriction. It is typically made of carbon steel, and the main components of the device are. Orifice ports are accurately machin ed f or precision measur ements. It is used for robust applications as it is known for its durability and is economical. Universal type orifice plate the universal type orifi ce plate is designed to be used in an orifi ce fi tting. Depending on the service, these seals are made of nitrile, tfe, or stainless steel. Materials rtj type orifice plates may be machined in one piece, or alternatively from two pieces, with an orifice plate screwed onto a carrier ringgasket. Orifice flow meter works on the principal of reduced pressure just downstream of orifice plate due to reduced flow diameter for the fluid. The performance of an orifice plate flowmetering system can be. Stockham northrop grumman information technology major dirk plante defense threat reduction agency dtra if flow through an orifice s minimum area is maintained at mach 1, the volume flow rate is only a function of the temperature and the pr essure upstream of the orifice. The orifice plate is a metal disc with a concentric hole in it, which is inserted into.
An orifice meter is a device used for measuring the rate of fluid flow. Differential pressure type flow meters head flow metersmeasure flow rate by introducing a constriction in. I have a submersible body thats about 3m tall and that takes in water from the bottom through three 120mm holes and allows the air to escape at the top through three 50mm holes. An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting flow in the latter two cases it is often called a restriction plate. Pharaohs and that the romans used orifices to meter water. When a fluid whether liquid or gaseous passes through the orifice, its pressure builds up slightly upstream of the orifice. An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting.
Orifice plate assemblies with rtj holder the plate holder assembly is a combination of plate holder and an orifice plate designed for ring tongue joint rtj flanges. Dagostino georgia institute of technology, gtr1a z4sl acoustics and aerospace technologies branch atlanta, georgia 303320844 grant nag i 1734 31 march 2000 submitted to national aeronautics and space administration langley. Iso5167 standard the multiholes orifice plate is a nonstandardized flow element but is designed and manufactured according to iso5167 standard requirements. A universal equation for the calculation of discharge coefficients of orifice plates. Model 5 720 calibrated orifice flow meters are desig ned for measurin g flows of air or g ases at pressures up to 100 psig and temperatures to 700 of. Venturi meter and orifice meter are the commonly used flow meters for measuring massvolumetric flow rate or velocity of the flowing fluid.
Orifices with dd2 tapping will have their pressure tapping, one pipe diameter before and. The orifice under consideration was circular diameter 0. When this orifice plate is placed in a line, a differential pressure is developed across the orifice plate. An introduction to an orifice meter 909 words bartleby. To find the coefficient of discharge for venturi meter. Line sizes 210 require a removable orifi ce plate seal. It shows how bernoullis equation and the continuity equation are used to derive the equation for. Nonnuflo brand dual chamber fittings may require a nitrile seal ring. The plate holder has a function of holding the orifice plate and also a function as a gasket to prevent leakage of the process fluid. Summary periodically aft arrow users pose the question of what cda value to use for modeling choked flow through an orifice. The orifice plate is basically a thin metal plate 1. Nov 20, 2016 venturi meter and orifice plate effects are two main and very important phenomenas in fuild mechanics sub field of mechanical engineering. A fluid passing though an orifice constriction will experience a drop in pressure across the orifice.
Like the venturi meter, the pressure difference varies directly with the flow rate. Im calling it a knifeedge orifice, or just a, you can imagine it being a plate in the center of my flow field, and has a very sharp edge. This means that although cheap to install, an orifice plate may cause six or seven times the pumping loss of a venturi which has a coefficient of 0. Oct 03, 2015 as the name implies, it consists of an orifice plate which is the basic element of the instrument. An orifice is an opening of a specific dimension removed from the head orifice plate which can be characterised by its shape or type of edge in the side base of a show more content best results occur between value of 0. Universal orifice plates type 500 the type 500 orifice plate is a standard design used in most brands of single and dual chamber orifice fittings. Pdf orifice plate meter is the most popular type of obstruction flow meter devices, due to its simplicity, low maintenance required, and long. Venturi meter and orifice plate effects are two main and very important phenomenas in fuild mechanics sub field of mechanical engineering. Each orifice plate has model number and orifice diameter stamped on tab for easy identification and selection. It is difficult to accurately calculate the flow of a gas or liquid through a tiny orifice due to. Quarterant the inlet edge of the bore of this orifice plate is rounded to a quarter circle. The orifice plate has a tab or printed label on one side where the specifications for the plate are stamped.
Line sizes 12 and above require the seal to be vulcanized to the o. It uses the same principle as a venturi nozzle, namely bernoullis principle which states that there is a. Calibration of an orifice plate flowmeter mechanical engineering department king saud university riyadh submitted by. For differential pressure elements, the calculation of pressure. The sizing of multiholes orifice plates is achieved in our design office with the same software as the one used for sharpedge orifice plates in compliance with the iso5167 standard. Orifice plates are recommended for clean liquids, gases and low velocitysteam flows. Acoustic absorption characteristics of an orifice with a mean bias flow k. Upon close examination of the orifice plate, the edge appears to have more of a rounded than a sharp edge quality. Orifice plate assembly dimensions x52e the claval model x52e orifice plate assembly is typically used with claval flow control valves. The x52e uses a wafer design holder which offers a compact lightweight assembly that is easy. Calculation of differential pressure with known flow and bore. This change can be used to measure the flowrate of the fluid.
Theory overview of flow measurement using differential pressure devices based on iso5167 standard. Orifice plates are most commonly used primary elements for flow measurement in pipelines based on the principle of measurement of differential pressure created when an obstruction is placed in the fluid flow, due to increase in fluid velocity. The orifice plate has a tab or printed label on one side where the specifications for the plate. In fact, this allows squareedged orifice plates to be used for measuring bidirectional flow rates where the fluid flow direction reverses itself from time to time.
This chapter describes the main design specifications for orifice plates more precisely, orifice meters. Theory overview of flow measurement using differential. The plate is similar to the type 500 orifice plate but has a 2in. Stockham northrop grumman information technology major dirk plante defense threat reduction agency dtra if flow through an orifices minimum area is maintained at mach 1, the volume flow rate is only a function of the temperature and the pr essure upstream of the orifice. Discharge coefficients of squareedged orifices for measuring. Im calling it a knifeedge orifice, or just a, you can imagine it being a plate in the center of my flow field, and has a very sharp edge to it. It consists of an orifice plate which is the basic element of the instrument. The edge of the orifice plate generally has a special shape in order to minimize contact between the fluid and the orifice plate.
The vena contracta corresponds to the narrow throat of a venturi tube. Standard material grades for orifice plates include 316 stainless steel, 304 stainless. There is a pressure tap upstream from the orifice plate and another just downstream. Orifice plates have a disadvantage of permitting a greater pressure loss than other throttle elements flow nozzles, venturi tubes, itabar, etc.
This seal ring is available as an optional accessory from cameron. It shows how bernoullis equation and the continuity equation are used to derive the equation for flow rate from a measured pressure drop. Differential pressure is proportional to the flow velocity and density of. Each assembly consists of one orifice plate and two orifice rings. In the case of a sharpedged orifice, the effective diameter is 0. Product data sheet fmoprtja rtj type orifice plates. Either a volumetric or mass flow rate may be determined, depending on the calculation associated with the orifice plate. Consists of onepiece ss orifice plates shaped to fit the contour of the union seat balltocone, eliminating the need for gaskets. Introduction an orifice meter is a type of flow meter used to measure the rate of flow of liquid in form of steam, using the differential pressure measurement principle. To determine the coefficient of discharge of the orifice meter 1. This white paper provides an overview of orifice meter technology, its advantages and general. As liquid flows through the pipe, the flow suddenly contracts as it approaches the orifice and then suddenly expands after the orifice back to the full pipe diameter. As fluid flows through the pipe, it has a certain velocity and a certain pressure.
Iso 5167 2 orifice plates pdf download download 2e535bee6a to bs 1042 and iso 5167. Fm 308 flow measurement by venturi and orifice meter. I am trying to work out the pressure inside the body, using standard orifice. An orifice meter consists of a flat plate that has a sharpedged hole accurately machined in it and placed concentrically in a pipe as shown in figure 12. The default calculation involves air passing through a. It uses the same principle as a venturi nozzle, namely bernoullis principle which says that there is a relationship between the pressure of the fluid and the velocity of the fluid. An orifice meter is a conduit and a restriction to create a pressure drop. Orifices an orifice is a submerged opening with a closed perimeter through which water flows. Orifices are analyzed using the following equation. Fm 308 flow measurement by venturi and orifice meter objectives. The calculation takes account of the fluid and fluid conditions, the pipe size, the orifice size.
Critical orifice theory, design and implementation dr leo w. In this post the effect of venturi meter and orifice plate on the fluid flow will be disciussed and complete work will be presented in the form of report. Orifice plate free download as powerpoint presentation. Q discharge in cfs c coefficient of discharge from handbook of hydraulics, king and brater, 5th. This orifice plate creates a measurable pressure difference between its upstream and downstream sides. Acoustic absorption characteristics of an orifice with a. The iso5167 standard condenses all this experimental information. Restriction orifice plates and critical flow devices.
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