Universal type orifice plate the universal type orifi ce plate is designed to be used in an orifi ce fi tting. An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting. Generally the plate holder is of soft iron material. Either a volumetric or mass flow rate may be determined, depending on the calculation associated with the orifice plate. Gaskets are provided to seal both sides of the plate.
Orifice ports are accurately machin ed f or precision measur ements. If the orifice discharges free into the air, there is modular flow and the orifice is said to have free discharge. Types of orifice plates advantages and disadvantages. It shows how bernoullis equation and the continuity equation are used to derive the equation for flow rate from a measured pressure drop. The differential pressure generated is related to the beta ratio of the orifice plate. Anorifice plateis 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. To determine the coefficient of discharge of the orifice meter 1. The secondary element consists of a differential pressure device together with a mechanism that translates the pressure difference into a rate of flow and indicates the result. The maximum velocity and minimum static pressure occurs at.
Inserting the higher discharge coefficient value of 0. 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 as pipe vibration, noise and pipe erosion may occur. The most commonly used inferential or rate meter is the thinplate, concentric orifice meter which is the primary device discussed in this paper. An orifice plate is an instrumentation device which is used for measuring the gas or liquid flow rate, reducing the pressure of flowing fluid or gas, and restricting the flow rate. Using equation 1, the orifice meter theoretical flow rates were. With an orifice plate installed in a flow stream, increase in fluid flow velocity through the reduced area of the orifice develops a differential pressure across the orifice. As the fluid approaches the orifice the pressure increases slightly and then drops suddenly as the orifice is passed. An orifice meter consists of a flat plate that has a sharpedged hole accurately machined in. Theory overview of flow measurement using differential. The shape of the orifice flow meter and orifice above restriction is a common form and in general there is a difference in the profile of the hole of the second orifice. It is mainly used for robust applications as it is known for its durability and is very economical.
Corner tapstaps located at the face of the orifice plate normally used in the line sizes smaller than 2. Consists of onepiece ss orifice plates shaped to fit the contour of the union seat balltocone, eliminating the need for gaskets. Devices paddle type orifice plate industrial controls. Can be used with gases, liquids, corrosive, and high temperature fluids.
Although it is a simple device, the orifice plate flow meter is, in principle, a precision instrument. It was designed for use wherever there is an application for a conventional flow orifice plate. Aga report number 3 and api manual of petroleum measurement standards. Each set of reversed plate tests consisted of a baseline and a reverse plate. Multi hole orifice plate calculations cr4 discussion thread. With an orifice meter, the orifice together with the adjacent part of the pipe and the pressure connections constitute the primary element. Depending on the service, these seals are made of nitrile, tfe, or stainless steel. Orifice plates are typically sandwiched between two flanges of a pipe joint, allowing for easy installation and removal. Designed for use wherever there is an application for a conventional. An orifice is an opening in the side or base of tank or reservoir through which fluid is discharge in the form of a jet.
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. Line sizes 12 and above require the seal to be vulcanized to the o. It is evident that the fully developed velocity profile becomes distorted as the flow approaches the upstream face of the orifice plate. Investigation of flow through multistage restricting orifices. 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. Characterization of highpressure cavitating flow through a thick. Is related with adiabatic expansion of the fluid in the bore zone. Iso 5167 orifice plate flow meter excel spreadsheet. These equations allow for not only the usual hydrostatic forces but also the forces due to friction.
Orifice plates are normally made to a certain thickness to avoid sudden gas surges from. It incorporates a stainless steel orifice plate with a unique holder or carrier ring containing metering taps and integral gaskets. Orifice plate flow measurement civil engineering free. As the name implies, it consists of an orifice plate which is the basic element of the instrument. It continues to drop until the venacontracta is reached and then gradually increases until at approximately 5 to 8 diameters downstream a maximum pressure point is reached that will be lower than the pressure upstream of the orifice. The series op orifice plate flow meteris a complete orifice plate flow metering package. Sometimes a drain or vent hole is provided where plates meet the pipe to avoid accumulation gas and air bubbles in the tube. The line size, flange rating, orfice bore, and plate material is stamped on the handle. L 1877macweld 6229353 24 lougar avenue, sarnia, ontario n7s 5n7. Jan 02, 2016 a photograph of an integral orifice plate and transmitter is shown here,in an application measuring the flow of purified oxygen gas through a copper pipe.
Imdp issue 1 orifice plates, orifice flanges, metering. Pdf purpose the sensitivity of orifice plate metering to poorly conditioned and swirling. Dynamic behaviour of flow through multistage restricting. Figure 3a represents the velocity vectors for a single orifice of diameter ratio d r 0. It was designed for use wherever there is an application for a. Pdf numerical methodology for orifice meter calibration. System dynamics p 3 orifice plates basic differential pressure theory differential pressure flow meters work on the principle of partially obstructing the flow in a pipe. When a fluid whether liquid or gaseous passes through the orifice, its pressure builds up slightly upstream of the orifice. Orifice plate theory software free download orifice plate. A differential pressure meter creates a pressure drop by combining a conduit and a restriction. Handbook of chemical hazard analysis, appendix b click on pdf icon, wait and then scroll down to page.
A common operating problem is orifice plates installed backwards. Paddle type orifice plates series 520 series 520 the paddle type orifice plate series 520 is designed for use between orfice flange unions. While the restriction orifice hole has a straight profile. Check the tag number of the orifice plate to ensure it is the correct unit for the location see fig 2. Line sizes 210 require a removable orifi ce plate seal. As the differential pressure type flow meter, such as venturi and orifice plate, becomes more applicable in the accurate flow metering applications, the understanding on its performance in various installation configurations is becoming critical in order to ensure the overall measurement accuracy requirement is. The orifice plate is available in standard material such as ss316, ss304, ss316l, monel, hastelloyc, etc.
Pdf development of the orifice plate with a cone swirler flow. Orifice plate assemblies with rtj holder flow measuring. An orifice plate is a thin plate with a hole in it, which is usually placed in a pipe. The discharge will depend up on the head of the fluid h above the level of the orifice. 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. Orifice plates are also used to reduce pressure or restrict flow, in which case they are often called restriction plates. Orifice plate free download as powerpoint presentation. The device is mainly used when the transfer of hydrocarbons from one entity to other entity has to take place. Orifice plate theory software orifice design calculator v. 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. 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. Pdf design and validation of a calibrated orifice meter for sub500. This is simply a metal plate with a hole in the middle for fluid to flow through. In the case of a sharpedged orifice, the effective diameter is 0.
This part of iso 5167 defines terms and symbols and establishes the general principles for methods of measurement and computation of the flowrate of fluid flowing in a conduit by means of pressure differential devices orifice plates, nozzles and venturi tubes when they are inserted into a circular crosssection conduit running full. Orifice plate theory software free download orifice. Orifice flow meter generally have a profile for the first pit straight, but then notched bevel with a slope of about 45. Orifice plate article about orifice plate by the free. Each orifice plate has model number and orifice diameter stamped on tab for easy identification and selection.
Flange tap pressure drop readings determine flow on chart on page 3. A little downstream of the orifice the flow reaches. Applications include steam flow, boiler feedwater, and fluid flow rates in building water lines. 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. Plates can be configured as recessed, pressed, or pressed with tab to identify size without breaking the union. It is one of the simplest and most costeffective ways to restrict flow. Orifice plate is one of the most popular differential pressure type liquid flowmeter generally employed for detection or measurement of flow. The task of properly sizing an orifice plate for any given application is complex enough to recommend the use of special orifice sizing computer software provided by orifice plate manufacturers.
Orifice plates series orc flow type orifice plates bore diameter as specified by customer w t o. It uses the same principle as a venturi nozzle, namely bernoullis principle which states that there is a. 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. Under ideal conditions, the inaccuracy of an orifice plate can be in the range of 0. Aug 28, 2009 this is the theory behind and orifice plate and venturi. In practice, valve designers usually combine the two methods to. In fiscal applications orifice plates are regularly removed and inspected to. The holder ring has a function of holding the orifice plate and also a function as a gasket to prevent leakage of the process fluid.
Single orifices or arrays of them constituting perforated plates, are. The smaller the beta ratio, the higher the differential pressure generated. For each direction, one owmeter, a or b, records the discharge owing in the setup with an electromagnetic owmeter endresshauser. It is evident that the fully developed velocity profile becomes distorted as. Pdf accurate and reliable ventilation rate is an essential input and can be a. 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. Discharge coefficient performance of venturi, standard.
This is the most common tap configuration and is recognized by the latest aga specifications. Orifice plates, orifice flanges, metering runs and venturi tubes 2 orifice plates imdp issue 1 3 2 orifice plates 2. This purpose is accomplished in, essentially, two steps. Of all the pressurebased flow elements in existence, the most common is the orifice plate. May 25, 2017 basics of differential flow devices venturi tubes, orifice plates, and flow nozzles duration. Orifice plates are, however, quite sensitive to a variety of errorinducing conditions. The orifice influences the flow field both upstream and downstream of the orifice plate. It is known that if severe cavitation occurs at piping in which the restriction orifice is installed, the trouble such. There have been several papers written identifying the errors in flow for 4. The plate is similar to the type 500 orifice plate but has a 2in. Imdp issue 1 orifice plates, orifice flanges, metering runs. Thin, square edge, bored orifice plates are installed between pyronics adapto flanges. Measurement to provide data acquisition and stable.
The plate holder along with the orifice plate can be also machined from one piece. Critical orifice theory, design and implementation dr leo w. Orifice plate flow meters are differential pressure sensors for flow rate. Physical setup at lch head losses are evaluated in both ow directions from inlet a to exit b and from inlet b to exit a. The most commonly used inferential or rate meter is the thin plate, concentric orifice meter which is the primary device discussed in this paper. Based on this functioning principle, the most used flow meters are orifice. Flow straightener b orifice box flow straightener a 4,00 0,50 1,75 0,16 2,15 figure 2. Orifice flow calculation data sheet calculating an orifice diameter it is difficult to accurately calculate the flow of a gas or liquid through a tiny orifice due to the effect of the leading edge of the orifice. A nozzle, venturi or thin, sharpedged orifice can be used as the. Pdf orifice meters are mechanical devices used to measure gases and liquids flows.
Singlephase and twophase flow through thin and thick orifices. Moreover, their acquisition and operation costs are smaller than the ones. Upon close examination of the orifice plate, the edge appears to have more of a rounded than a sharp edge quality. As the differential pressure type flow meter, such as venturi and orifice plate, becomes more applicable in the accurate flow metering applications, the understanding on its performance in various installation configurations is becoming critical in order to ensure the overall measurement accuracy requirement is met. The beta or diameter ratios of concentric orifice plates range from 0.
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