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CEESI Orifice Meter Publications

The following are a selection of papers written by CEESI engineers regarding orifice. If you would like addition information on this type of meter, or on other flow measurement topics, search the Flow Measurement Technical Library. Please read the CEESI Disclaimer before downloading any CEESI publications.


Effects of Abnormal Conditions on the Accuracy of Orifice Measurement
Bill Johansen,  2000, 75th International School of Hydrocarbon Measurement

Abstract:
The effects of abnormal conditions on orifice plate based flow measurement is a broad topic. The research on abnormal effects has typically focused on issues such as the effects of bent plates, plate eccentricity, dulled orifice bore leading edge, the presence of water and liquified hydrocarbons, and many other conditions found in pipeline orifice meters. Abnormal conditions may also describe conditions that are considered acceptable as they are within the guidelines specified by standards like ANSI/API 2530. ANSI/API 2530 is the standard that covers orifice plate based flow measurement of natural gas. It contains equations for calculating flow, specifications for the installation of orifice flow meters, and methods for gas sampling. This paper will discuss potential problems in four areas of orifice based flow measurement: calculation of discharge coefficients, calculation of expansion factors, flow conditioning, and gas sampling. Each of these topics is covered by the standard but a great deal of detail is left out of the standard. In many cases only a detailed knowledge of the history behind the standard allows flow measurement personnel to recognize when potential problems are arising.
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Effects of Entrained Liquid on Orifice Measurement
Bill Johansen,  1999, American School of Gas Measurement Technology

Abstract:
Natural gas often has some liquid content. The liquid may be water, hydrocarbons, or compressor oil. As this gas flows through an orifice meter is the gas being measured correctly? The measurement methods and calculations described in ANSI/API 2530 are for dry gas. Many researchers have studied the effect of entrained liquids on orifice measurement. The existing literature can provide much information about orifice flowmeter errors. This information can be used to determine the course of future orifice plate research efforts. This paper will discuss four test programs that were conducted to examine the effects of entrained liquids on orifice meter performance. The results of these programs will be discussed as well as some simple flow models. The flow models will be used to explain why research into this area has been so difficult. The flow models are not intended as a guide for measurement correction.
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The Effects of Oil Coating on the Measurement of Gas Flow Using Sharp Edged Orifice Flowmeters
Bill Johansen and Tom Kegel,  1996, Forum on Fluid Measurements and Instrumentation

Abstract:
Orifice plates are known to be sensitive to a variety of effects due to dimensional variations and flowing fluid conditions. A number of studies have been performed to determine the specific effects of water entrainment and two phase flow on orifices, but the results were not well documented and were limited in scope. This paper describes an investigation funded by the Gas Research Institute (GRI) to determine the effects of a coating of compressor oil on the flowmetering performance of orifice plates. A viscous oil is used to coat only the plate or both the plate and upstream piping. The effect of this coating on orifices having different diameter ratios (B) in several different line sizes is evaluated by statistically comparing the discharge coefficient for the wetted orifice to the discharge coefficient when dry.
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Effect of Liquid Entrainment on the Accuracy of Orifice Meters for Gas Flow Measurement
V.C. Ting and G. P. Corpron,  1995, International Gas Research Conference

Abstract:
This paper presents the results of a study to show that a small amount of liquid entrainment in an orifice meter can affect the accuracy of gas flow measurement. A series of tests, sponsored by Chevron Petroleum Technology Company, was conducted under controlled conditions at the Colorado Engineering Experiment Station, Inc. (CEESI) air flow calibration facility to study this effect. Eight-inch orifice meters were selected for the experiments. The tests were conducted at 4.13 MPa (600 psia) over the orifice Reynolds number range from 4 to 9 million using two horizontally mounted orifice meters. Water was injected at a controlled rate upstream of the orifice meter to simulate field conditions. It was found that the presence of a small amount of liquid in the gas stream caused the orifice meters to read a lower gas flow measurement by as much as 1.7% depending on the beta ratio and the liquid rate.
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The Orifice Expansion Correction for a 50 mm Line Size at Various Diameter Ratios
Walt Seidl,  1995, 3rd. International Symposium on Fluid Flow Measurement

Abstract:
The expansion coeffiecient or factor for a compressible flowmeter corrects for the change in pressure and density as the fluid is accelerated through the flowmeter. The expansion correction currently in use in the United States and also in other countries was developed over fifty years ago by Buckingham(1) and Bean.(2) More recent work reported by Kinghorn(3) shows the equation currently in use to be in error. This paper describes the results of a test program to determine the expansion factors for flange-tapped sharp-edged orifices with diameter ratios between 0.242 and 0.726 in a nominal 50 mm (2 inch) line. Critical flow Venturis are used as the reference standards and dry air as the flowing fluid. The ratio of differential pressure to inlet static pressure is varied over a range of zero to about 0.2 at a constant Reynolds number. The expansion factor is determined from the apparent change in discharge coefficient at a constant Reynolds number.
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Effects of Abnormal Conditions on the Accuracy of Orifice Measurements
Steve Caldwell,  1993, 68th International School of Hydrocarbon Measurement

Abstract:
The orifice meter is one of the most widely utilized measurement devices and is one of he oldest, next to the bucket. The orifice meter is one of the most basic devices ever invented for measurement and has many advantages because of its simplicity and also has many associated problems as a result of its simplicity.
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Effects of Abnormal Conditions on the Accuracy of Orifice Measurements
Taft Snowdon,  1990, 65th International School of Hydrocarbon Measurement

Abstract:
The orifice meter remains the foremost measurement device used on the industry for hydrocarbon flow. The primary element of the orifice meter is the orifice plate and orifice meter tube consisting of the orifice fitting , or flanged pressure taps, adjacent piping and the flow conditioner or straightening vanes. The complete system also includes the temperature and pressure measuring devices used often called the secondary element and the pressure lines from the taps to the pressure instruments. The American National Standard Institute/American Petroleum Institute Standard 2530 (ANSI/API 2530) also called the AGA-3, provides specific recommendations for the manufacture, inspection and installation of an orifice meter. In order to insure accuracy, with minimum uncertainty, these guidelines and inspection procedure should be established by taking relatively fundamental measurements of the primary element components.
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New Data for the Quadrant Edged Orifice
Charles Britton and Steve Stark,  1986, International Symposium on Fluid Flow Measurement

Abstract:
New experimental data is presented for both quadrant-edge and sharp-edge orifice plates used in low Reynolds number applications. Twelve different orifice plates with diameter ratios (Beta ratios) from 0.25 to 0.54 were calibrated in 76mm (3") and 102 mm (4") pipe using flange taps. A white mineral oil with a kinematic viscosity of approximately five centistokes was used as the calibration fluid which resulted in a pipe Reynolds number range of from 290 to 45,000. Calibration data is presented for piping lengths that meet the requirements of AGA Report-3 (ANSI/API-2530). Additional calibration data is presented where a flow conditioner was located three pipe diameters upstream of the orifice plate. A comparison of the discharge coefficient values of this new data to the value predicted by former investigators is given.
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Effects of Abnormal Conditions on the Accuracy of Orifice Measurements
Steve Caldwell,  1974, 62nd International School of Hydrocarbon Measurements

Abstract:
Abstract not available.
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