Measurement Library

PRCI Publications (2013)

PRCI

PR-004-12602-R01 Performance of H2S Sensors - Unblinded
Author(s): Donatello, Janos, Crippen
Abstract/Introduction:
Three hydrogen sulfide (H2S) monitors calibrated to detect concentrations between the ranges of zero to fifty parts per million (ppm) were acquired by the PRCI project advisory team and sent to GTI for evaluation. The three tested monitors were from different manufacturers using different detection methods and technologies. Each of the three H2S monitors was evaluated using testing protocols to determine the accuracy, precision, and signal response of each monitor.
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PR-004-12602-R02 Performance of H2S Sensors
Author(s): Donatello et. al.
Abstract/Introduction:
Three hydrogen sulfide (H2S) monitors calibrated to detect concentrations between the ranges of zero to fifty parts per million (ppm) were acquired by the PRCI project advisory team and sent to GTI for evaluation. The three tested monitors were from different manufacturers using different detection methods and technologies. Each of the three H2S monitors was evaluated using testing protocols to determine the accuracy, precision, and signal response of each monitor.
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PR-015-07603-R01 Effect of Orifice Plate Manufacturing Variations on Orifice Meter Performance - Blinded
Author(s): Nored, James
Abstract/Introduction:
An investigation to flow test and measure a large set of orifice plates to determine the proportion of existing orifice plates have measured discharge coefficients outside of the Reader-Harris/Gallagher equation 95% confidence limits. The research determined if the existing tolerance specifications adequately describe the dimensions of an orifice plate required to conform to the Reader-Harris/Gallagher equation calculated discharge coefficient. The testing also underscored the influence of manufacturing variations on orifice plate performance.
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PR-015-07603-R02 Effect of Orifice Plate Manufacturing Variations on Orifice Meter Performance - Unblinded
Author(s): Nored, James
Abstract/Introduction:
An investigation to flow test and measure a large set of orifice plates to determine the proportion of existing orifice plates have measured discharge coefficients outside of the Reader-Harris/Gallagher equation 95% confidence limits. The research determined if the existing tolerance specifications adequately describe the dimensions of an orifice plate required to conform to the Reader-Harris/Gallagher equation calculated discharge coefficient. The testing also underscored the influence of manufacturing variations on orifice plate performance.
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PR-015-08605-R02 Assessment of Orifice Meter Flow Measurements with Low Differential Pressures
Author(s): George, Jowers, Grimley
Abstract/Introduction:
Measurement of natural gas flow with an orifice meter is a well-established methodology however, orifice measurement accuracy is of concern when flow rates are low and the differential pressure (DP) across the orifice is at the extreme low end of common DP transmitter ranges. This research evaluated the performance of multiple types of transmitters in 10-inch and 4-inch orifice meter runs at differential pressures approaching 1 inch of water column (1 H2O), simulating low flow transmission meter stations and depleted production well stations. The results were analyzed to characterize and better understand the uncertainties and measurement errors associated with orifice meters operating with small bore diameters and low DPs. Transmitters tested included typical DP transmitters with stated accuracies of 0.1% of full scale, DP transmitters with stated accuracies as a percent of reading and high-frequency-response DP transmitters. Data acquisition methods, transmitter technologies, and various calibrated measurement spans were studied for their potential to improve orifice meter accuracy at low DP conditions. This is an blinded report.
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PR-015-11702-R01 Evaluation of Enhanced Diagnostics for Orifice Meters
Author(s): George, Hawley
Abstract/Introduction:
A large installed base of orifice meters, many installed where newer technology meters are impractical, accounts for a significant fraction of the measured volume of natural gas in the United States. Ultrasonic meters are newer technology meters that provide integrated diagnostics to monitor the meters health and identify flow problems such as distorted velocity profiles and other operational issues. The need exists for similar diagnostics for orifice meters to identify operational causes of measurement errors (and possibly measure their magnitudes), allow users to perform orifice meter maintenance as needed, reduce maintenance costs, and reduce the fiscal impact of significant measurement errors. Research was conducted to identify and recommend candidate technologies for development into practical, cost-effective orifice meter diagnostic tools..
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PR-015-11707-R01 Test Diagnostic Methods for Turbine Gas Meters
Author(s): Hawley
Abstract/Introduction:
Similar to most metering technologies, turbine meters are known to be affected by abnormal flow or abnormal mechanical conditions which can cause bias in flow measurement. These types of flow conditions include blockage at the flow meter or straightening vanes, grime or liquid contamination on the internal meter components, damage to the internal meter components, and pulsation in the flow. With the introduction of ultrasonic and Coriolis meters for gas applications, the natural gas industry has embraced the concept of meters with embedded diagnostic capabilities. These capabilities allow the detection of potential problems with the flow behavior or meter condition that may lead to measurement error. Diagnostic measurements also exist for turbine meters. Some turbine meter manufacturers provide techniques for diagnosing proper meter performance through approaches that include unique design attributes (e.g., dual-rotors) or by monitoring the characteristics (shape, timing, etc.) of the pulses produced as blades pass a sensor. Various analog and digital signal analysis methods exist to interpret the output pulse characteristics to determine meter condition attributes such as bent blades and bearing wear. The objective of this research was to assess, through flow testing, the ability of various diagnostic methods to detect abnormal flow and abnormal mechanical conditions for both single and dual-rotor turbine meters. A secondary objective was to determine the amount of flow measurement error that could be present for the various flow conditions that were tested. The approach was to test three different diagnostic methods on a single-rotor and dual-rotor turbine meter at the Metering Research Facility at Southwest Research Institute. The selected diagnostic methods were the Smith MeterTM AccuLERT II from FMC Technologies, TurbinScope from Elster-Instromet, and The Turbo Corrector from Mercury Instruments. Tests were performed under controlled conditions and were designed to determine the ability of the selected diagnostics to detect various levels of flow meter or tube bundle blockage, grime buildup on the rotor or rotor bearings, damage to the rotor, or flow pulsations.
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PR-015-12600-R01 Ability of Ultrasonic Meters to Measure Accurately in Compressor-Induced Pulsating Flows
Author(s): George, Hawley
Abstract/Introduction:
Transmission and storage operations frequently move natural gas using reciprocating compressors that may generate flow pulsations. Most measurement systems cannot accurately measure the flow rate of a pulsating gas stream, and the resulting errors can cause inaccurate gas volumes and accounting imbalances. Recent advances in ultrasonic meters may provide the ability to function without measurement error in pulsating gas streams. Tests were performed to examine the relationship between ultrasonic meter transducer sampling rates, the frequency and amplitude of pulsations from reciprocating compressors, and meter accuracy as a possible basis for using ultrasonic meters in gas pipelines with varying pulsations. Two ultrasonic natural gas meters of current design were tested at SwRI in flows that simulated reciprocating compressor pulsations. Diagnostics and flow data were collected from the meters and analyzed to identify pulsation conditions in which the meters read accurately, or in which meter data could be used to correct measurement errors.
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PR-015-12601-R01 USM Accuracy Effects with Pressure and Temperature Variations from Initial Calibration
Author(s): Witte, Hawley, Grimley
Abstract/Introduction:
Static environmental chamber tests and flow tests at various pressure and temperature conditions were conducted to determine the effects on flow measurement values for two ultrasonic meters from two different manufacturers. Mechanical dimension changes produced by stress from pressure and thermal expansion or contraction at state conditions different from dry calibration and flow calibration conditions in the meters were predicted. The predicted flow measurement error was compared with the actual flow measurement error.
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PR-015-12605-R01 Effect of Upstream Piping Configuration on Ultrasonic Meter Bias
Author(s): Hawley, Owston
Abstract/Introduction:
This research investigated the effects on ultrasonic meter performance of header configurations upstream from a default AGA-9 meter run. To minimize the expense of experimentally testing numerous header configurations, the approach of this research was to use Computational Fluid Dynamics (CFD) to model multiple header configurations. The CFD model used for this research was developed by using experimental data from a previous PRCI-funded project (Contract PR-015-10603) to tune and validate the model. Twelve header configurations were evaluated using the developed CFD model. The 12 header configurations were selected based on input from the PRCI project committee. The effect of the headers on measurement error was assessed for Daniel and Instromet path configurations.
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PR-015-12606-R01 Thermal Irradiance Effects on Ultrasonic Meter Performance at Low Flow Rates
Author(s): Witte, Grimley, Thorson
Abstract/Introduction:
This study was focused on determining the effects of thermal radiant energy on ultrasonic meter accuracy at flow rates less than 10% of meter capacity. A straight run ultrasonic meter installation consistent with the recommendations of AGA Report Number 9 was assembled, and arrays of heat lamps were mounted above the meter run. The heat lamp arrays were energized in banks in order to simulate different modes of shading of the meter run assembly to determine the influence of solar radiation on flow measurement at low flow rates. Observed flow measurement errors were evaluated by analysis of ultrasonic meter diagnostic log data and through various temperature measurements on the pipe surface and measurements taken at the pipe centerline. The effectiveness of using a stepped thermowell compared to a bare RTD was also evaluated in these tests.
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PR-015-13603-R01 Meter Station Design Procedures to Minimize Pipe Flow-Induced Pulsation Errors
Author(s): George, et. al
Abstract/Introduction:
This project explored the sources of flow-induced pulsations in natural gas meter stations and the detrimental effects the pulsations have on the measurement capabilities of three types of gas custody transfer meters: orifice meters, turbine meters, and ultrasonic meters. To supplement the PRCI-funded research on the effect of compressor pulsations on ultrasonic flow measurement, Southwest Research Institute (SwRI) has performed a study to identify best practices for meter station piping design that avoid generating or amplifying flow-induced pulsations. This study involved a literature review to identify features of meter station piping that (1) generate pulsations independently of compressors or (2) amplify pulsating flows entering station piping. Where possible, the study also worked to quantify the effect of flow-induced pulsations on meter accuracy. This information has been used to create best practices and methodologies for minimizing metering errors caused by pulsation. As a result of this research, various design techniques able to reduce or eliminate pulsations in meter station piping systems have been compiled. Mitigation practices specific to obstructions, flow restrictions, piping geometries, gaps, acoustically-induced pulsation, and flow-induced turbulence are discussed. Additionally, common methods of filtering high-frequency pulsations are discussed in detail.
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PR-179-13601-R01 CFD Analysis of the Heat Transfer Characteristics and the Effect of Thermowells
Author(s): Xie, Gao, Olsen
Abstract/Introduction:
Thermowells are widely utilized for temperature measurement in metering stations on natural gas pipelines. The use of thermowells induces errors in the measurements of gas temperature due to the heat transfer processes involved in the thermowell installations, which results in errors in the flow rate calculations. In order to study the temperature measurement accuracy of using thermowells, a three-dimensional computational fluid dynamics study is performed and an in-depth investigation of the effect of the multiple variables on gas temperature measurement is carried out. The parameters under investigation include pipe diameter, thermowell type, thermal conditions at the pipe wall surface, and gas velocity. The study provides information on the sources of error and guidance to users on thermowell type selection and the pipe-thermowell installation, in order to improve the reliability and accuracy of gas temperature measurement.
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PR-343-12607-R01 Sensitivity of Clamp-On Ultrasonic Meters to Installation Effects and Pipe Condition
Author(s): Zanker
Abstract/Introduction:
From experimental data, published papers and manufacturers information, a Best Practices Guide to the Installation and Use of Clamp-On Ultrasonic Meters in Natural Gas Service has been produced. The guide provides information on the fundamental principals of Clamp-on meters in natural gas service as well as best practices for installation.
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PR-352-11703-R01 Maintenance and Test Intervals for Primary and Secondary Measurement Equipment
Author(s): Rans
Abstract/Introduction:
This report summarizes the work done to investigate existing maintenance and test intervals for primary and secondary measurement equipment. Advances in the accuracy and reliability of current measurement technology and the ability to apply Statistical Process Control (SPC) techniques to identify abnormal operating conditions that need to be investigated is changing the way we need to look at maintenance. Test intervals are determined based on four factors which are discussed in more detail in Section 3.4.2 Determination of Test Intervals and Tolerance Bands. Ignore Routine Variability - e.g.: Dont continually zero adjust an instrument which is experiencing small changes due to normal operating condition changes such as ambient temperature. Determine a Test Frequency Based on Equipment Degradation with Time - Use equipment reliability information to determine if the equipment routinely drifts. Determine a Test Frequency Based on How Long an Exception/Unexpected Meter Problem Can be Tolerated - The frequency is often related to the financial impacts and the size of the facility. Determine a Test Frequency Based on Contractual or Commercial Requirements - For example if the maximum period a measurement correction can be applied is 6 months, a test frequency of 6 to 12 months may be required to meet the requirement. The primary and secondary test interval is determined from the shortest test frequency determined by following these four steps.
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PR-352-11703-S01 Maintenance and Test Intervals for Measurement Equipment.xlsx
Author(s): Rans
Abstract/Introduction:
Simplified notes and a example spreadsheet on using XmR methods
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PR-381-12604-R01 Better Defining the Uncertainties for the AGA-8 Equation
Author(s): Lemon
Abstract/Introduction:
In order to revise the AGA-8 documentation for publication in 2014, better knowledge of the 0.1% uncertainty level in the equation of state is needed. The 0.1% uncertainty level has been identified by an AGA-8 task group as the acceptable limit of error for density and compressibility factor calculations. With the availability of a new high-accuracy wide-range equation of state described in the introduction, it is now possible to locate regions within AGA-8 that are most likely outside the 0.1% uncertainty limit, which was not possible in 1992 due to limited experimental data.
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