Measurement Library

American School of Gas Measurement Technology Publications (1999)

American School of Gas Measurement Technologies

Fundamentals Of Gas Laws
Author(s): John Chisholm
Abstract/Introduction:
In the gas industry a standard unit of measure is required. In the English system it is the standard cubic foot. In the metric, it is the standard cubic meter. This standard unit is the basis of all exchange in the gas industry. When the unit of purchase is the energy content (BTU) we achieve it by multiplying the BTU content of a standard cubic foot times the number of cubic feet delivered to the customer. So we must obtain standard cubic feet or meters. A standard cubic foot is defined as one cubic foot of gas at a pressure and temperature agreed upon by the buyer and seller. Common standard conditions are 14.73 psia and 60 Fahrenheit. The gas passing through a meter is rarely at standard conditions. It is necessary to convert the gas in the meter from the metered conditions to standard cubic feet. The tools we have for relating volume to pressure and temperature are Equations of State or, simply, the Gas Laws. The Gas Laws serve two purposes. They allow the conversion of a gas stream from metered conditions to standard conditions. They also provide an understanding of what the gas is doing and why. This paper will briefly present the Gas Laws and the physical properties of gas which the Gas Laws describe.
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Document ID: 0618E9DC

Basic Electronics For Field Measurement
Author(s): David R. Looper
Abstract/Introduction:
This paper hopefully affords readers a broad brushed overview of electronics basics and how they are utilized in todays increasingly technical world. There are references to established formulas and relationships as well as a discussion on some state-of-the-art technology. The latter is often short changed in these types of presentations and it seemed a good idea to hit some of these basics, too. Perhaps the discussion herein will prove at least informative to those that have limited exposure to computer technology. This understanding is more and more vital to the successful implementation of computerized measurement and automation systems in our Natural Gas Industry.
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Document ID: 387937B1

Fundamentals Of Energy Determination
Author(s): Thomas E. Sowell
Abstract/Introduction:
This paper presents fundamental information necessary to understand and appreciate the concept of total gas energy in a natural gas pipeline. That is, to be able to converse with peers within the natural gas industry and understand basic concepts and terminology. Discussed is the historical transition from volumetric measurement to total gas energy including some of the basic terminology, physics, measurement as well as the reasons for changes in methodologies. Included is industry acceptance of new concepts and regulations involving custody transfer as well as the instrumentation and systems involved in traditional and newer, more progressive forms of gas measurement.
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Document ID: 436F6853

H2S Detections And Determination
Author(s): Marshall T. Schreve
Abstract/Introduction:
Hydrogen Sulfide is measured in the natural gas industry for several reasons: Personal Safety Corrosion Control Contractual Obligation H2S means that each molecule of gas is made up of two hydrogen atoms and one sulfur atom. Hydrogen Sulfide is formed naturally by the decomposition of organic (previously living) animal and/ or vegetable matter by bacterial action. It is, therefore, found in crude, natural gas, sewers, swamps, and is also produced as a product or by-product in a variety of industrial and biological processes.
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Document ID: FF09B3E3

Instruments For The Determination Of Specific Gravity / Relative Density Of Gas
Author(s): Myles J. Mcdonough, Jr.
Abstract/Introduction:
The terms Specific Gravity and Relative Density have been used for a number of years. Yet there seems to be some confusion over what exactly they mean. Specific Gravity is formally defined as the ratio of gas density to air density when both are at standard conditions of 0 Degree C and 760 mm. Over the years the definition evolved to become the ratio of gas density to air density at the same temperature and pressure, Relative to each other. Hence, the term Relative Density. This is the most commonly used definition today. The fixed or Specific requirement of temperature and pressure, (0 degree C and 760 mm), had been removed over the years. The American Gas Association in 1985 officially replaced the term Specific Gravity with Relative Density. However, both terms are still used synonymously.
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Document ID: C04244AF

Operations Of On-Line Chromatographs
Author(s): Mark F. Maxwell
Abstract/Introduction:
On-line Chromatographs are commonly used to determine the individual components of a natural gas stream. The individual components are then used to calculate Btu and Specific Gravity. The chromatographic data is combined with flow rate data to calculate a total energy value. The energy value is then used for custody transfer. Accurate chromatograph data is a critical part of the gas measurement process. Because a wide variety of conditions exist, no standard rules can be applied to all installations. Each manufacturer usually supplies documentation regarding equipment installation. The manufacturer instructions should be followed as closely as possible. However, understanding the operation and principles involved allows system optimization for individual field conditions. Planning is an essential element of a successful chromatograph installation.
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Document ID: 3BAF0BBB

Techniques Of Natural Gas Composite Sampling
Author(s): Royce Miller
Abstract/Introduction:
The most important thing in taking a sample is where and how it is taken. A sample can be taken as a spot, composite, or as a continuous sample connected to a chromatograph.
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Document ID: DAC498FA

Techniques Of Gas Spot Sampling
Author(s): Thomas F. Welker
Abstract/Introduction:
There is no other way to receive proper payment for the natural gas that we purchase, transport, produce, process, or sell except by accurately determining its heating value, specific gravity, and compositional analysis. Regardless of whether the determination is made by using an on-line analyzer, gas sampler, or sending a person to collect a spot sample, the accuracy of the analysis is determined by the quality of the sample. The first factor that must be covered is the person chosen to physically take the spot sample, or install and maintain the sampling device. This person is the beginning of a successful sampling program. The final outcome of the sample operation will be determined by the efforts of this first link in an unbreakable chain of operations that must be performed without variances which can and will affect the outcome of the results obtained.
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Document ID: C572A3BB

Techniques Of Natural Gas Composite Sampling
Author(s): Royce Miller
Abstract/Introduction:
The most important thing in taking a sample is where and how it is taken. A sample can be taken as a spot, composite, or as a continuous sample connected to a chromatograph.
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Document ID: 66F864D9

Fundamentals Of Natural Gas Chemistry
Author(s): Steve Whitman
Abstract/Introduction:
In order to understand the chemistry of natural gas, it is important to be familiar with some basic concepts of general chemistry. Here are some definitions you should know:
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Document ID: FC203916

Fundamentals Of Egm - Electrical Installations
Author(s): Michael D. Price
Abstract/Introduction:
The areas of gas measurement and communications have seen substantial changes in the last few years as the natural gas industry adapts to effects of the economy, low gas prices, warm winters and government deregulation. Every company has studied, debated, hired consultants, and finally determined how gas flow data is to be measured and collected. All gas companies have hundreds and even thousands of points which must be accurately measured. Data is retrieved from very remote and rugged locations. Climate conditions can range from humid off-shore platforms to desert conditions with both temperature extremes included. No commercial power is available, allowed or even desired at these locations making the solar-powered electronic gas measurement equipment the ideal method of gathering flow data.
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Document ID: 648A2169

Fundamentals Of Orifice Metering
Author(s): Bill Buckley
Abstract/Introduction:
The purpose of this paper is to discuss the fundamental components used in orifice measurement.
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Document ID: AC46311C

Design Considerations For Orifice Meter Tubes Discussion Of API 14.3 Design Specifications
Author(s): Bulent Turan
Abstract/Introduction:
This paper will outline general guidelines that should be considered during orifice meter tube design and application. It should be noted that many producers, transmission and distribution companies have additional requirements for the design and implementation of the subject equipment. As an outline, the paper will describe and define design considerations with the use of the Domestic standards.
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Document ID: 53F80994

AGA Calculations - Old Vs New
Author(s): Brent Berry
Abstract/Introduction:
This paper is intended to help bridge the gap between the Old AGA-3 equation (hereafter referred to as AGA-3- 1985) and the New AGA-3 equation (hereafter referred to as AGA-3-1992). As such the paper begins with a background section aimed at assisting those who are mostly familiar with the factored form of the orifice metering equation.
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Document ID: C958F13B

Gri Metering Research Facility Update
Author(s): Charles E. French
Abstract/Introduction:
The Gas Research Institute (GRI) sponsors a comprehensive flow measurement research, development, and commercialization (RD&C) program aimed at improving metering performance in the field. This paper summarizes some of the recent accomplishments of the research program at the GRI Metering Research Facility (MRF), a high-accuracy natural gas flow calibration laboratory capable of simulating a wide range of operating conditions for the industrys research, calibration, and testing needs. The MRF, located at Southwest Research Institute (SwRI) in San Antonio, Texas, supports a variety of GRI-sponsored research and third-party test and calibration activities. Current GRI MRF research includes projects on orifice and ultrasonic flow meters and gas sampling methods. Through a portfolio of projects addressing priority research needs, the GRI measurement program provides significant benefits to the natural gas industry.
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Document ID: 2FCDD595

Meter Change-Out And Routine Testing Programs
Author(s): Don Yarbrough
Abstract/Introduction:
With the understanding that the gas meter is the cash register, it is important that the accuracy of that meter is maintained. This sets up the need for routine inspection. Routine inspection will be determined based upon the number of various types of meters a company may have.
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Document ID: CCC7F797

Onsite Proving Of Gas Turbine Meters
Author(s): Jim Beeson
Abstract/Introduction:
This paper examines a patented mobile gas turbine meter proving system that blends technology from liquid turbine meter provers with innovative ideas that particularly apply to gas measurement. NorAm Pipeline Service developed and now uses this mobile sonic nozzle prover on gas turbine meters ranging in size from 3 thru 16 at meter station sites under actual operating conditions. The prover also incorporates a gas chromatograph which uses the actual mass flow computations. This system has many enhancements over former methods of proving gas turbine meters. NorAm formerly proved its larger turbine meters, having capacities of 60,000 ACFH (Actual Cubic Feet per Hour), with a Roots transfer prover capable of only 10,000 ACFH. This meant the provings were at or near locations on the proving curve where the K-factor (Pulses per Actual Cubic Foot) might be in error for the turbine meters normal flow rate. With the prover NorAm can now prove a turbine meter at the rate it is actually flowing.
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Document ID: 29F1EAE4

Field Inspection And Calibration Of Measurement Instruments
Author(s): George E. Brown III
Abstract/Introduction:
Timely, diligent field testing and calibration of gas volume recording and correcting instruments ensure that measurement information fairly represents actual volumes. The instruments save a company capitol and operating costs because they can record or integrate volumes at pressures and temperature above the normal pressurebase conditions specified in contracts for volume calculation. This allows the company to use smaller and fewer meters. Recording and correcting instruments normally are connected to positive displacement, rotary and turbine meters in lieu of a direct reading/compensating index. The compensating instruments include:
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Document ID: E48BE56D

Unaccounted-For Gas
Author(s): Mike Haydell
Abstract/Introduction:
Unaccounted-for gas can be defined as the difference between the amount of gas purchased and the amount of gas sold through a measured gas distribution system. This difference is commonly described as a percentage of gas purchased: PERCENT UNACCOUNTED-FOR GAS.
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Document ID: AFF9BE96

Application Of Telemetering In Natural Gas Distribution
Author(s): Dale P. Moore
Abstract/Introduction:
SCADA (Supervisory Control and Data Acquisition) has become an integral component of the operations of a natural gas distribution company. Where once telemetry was primarily employed for pressure monitoring, now it is just as critical that businesses have accurate and timely data both of their customers and of their suppliers.
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Document ID: E4127D99

Principles Of Odorization
Author(s): Edwin H. Roberson
Abstract/Introduction:
The detection of natural gas leakage has long been a concern to the natural gas industry, but never more so than today. Increased public awareness of safety and huge increases in the cost of product liability litigation has resulted in a greater focus on gas odorization. While it must be recognized that no odorant will be 100% effective in warning of the presence of natural gas, basic knowledge about the properties and characteristics of odorants used for natural gas and an understanding about some of the potential problems in the odorization of such gas can be extremely helpful for those involved in the gas odorization process.
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Document ID: 7A5F3A86

Remote Meter Reading Methods( Of Retrieving Data By Use Of Remote Devices)
Author(s): John Schnitzer
Abstract/Introduction:
Remote devices for Automatic Meter Reading (AMR) have many common characteristics but vary depending on what kind of communication system is in place. A partial list of communication systems that current technology supports includes the following
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Document ID: E4FBC054

Fundamentals Of Orifice Recorders
Author(s): Micheal Bealer
Abstract/Introduction:
The American Gas Association defines the orifice meter as the complete measuring unit consisting of a primary and a secondary measurement device. The orifice meter body, tube and orifice plate are considered the primary measuring device. This primary device is equipped with pressure taps that allow for the hook-up of a secondary device to sense the output signal of the primary orifice meter. The secondary device is some type of recorder or datalogger that allows for the recording of the events (i.e. signal levels and changes) that are created in the primary device.
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Document ID: 66A82958

Periodic Inspections Of District Regulator & Relief Valves
Author(s): Jerry Bowins
Abstract/Introduction:
Inspection of District Regulator Stations and over pressure protection devices are essential in complying with Federal and State Regulations. In order to understand the functions of a District Regulator, we must start with the City Gate Station. Some pipeline people call City Gates, Town Border Stations. City Gate Stations are where distribution companies purchase natural gas from the pipeline. The gas is measured and odorized here. Measuring devices are usually installed by pipeline companies. Odorizers are installed by distribution companies. Pipeline companies bring the gas from the well head and it goes into a gathering system. The gathering system is where a pipeline transports gas from a current production facility to a transmission line or main.
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Document ID: 57078500

Field Testing By Transfer Proving An Explanation Of The Techniques And Procedures
Author(s): Ruben P. Sanchez, Jr.
Abstract/Introduction:
Aristotle once said, Science begins and ends with Measurement. Without question, measurement is a function that truly influences the economics of the gas industry. This is true because the revenue of the industry, for the most part, is determined by the registration from meters. This is why it is said that meters are the Cash Registers of the business. Therefore, it is essential for service companies such as Reliant Energy to prove or test each meter. Transfer Proving is a portable method of meter performance testing. The methods to prove meters must continually be improved to assure accuracy of revenue at the lowest feasible maintenance costs.
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Document ID: 7FB0CED7

Design And Installation Of A Complete Measurement And Control Facility
Author(s): T. G. Quine
Abstract/Introduction:
This presentation is intended to illustrate the implementation of a successful project. These principles can be applied to measurement and control projects, LNG projects, and LPG projects. The strategy presented involves performing through preliminary engineering, performing final design and procurement, qualification of installers, construction, testing, commissioning and finally, training and documentation.
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Document ID: 6D33534E

Meter Selection For Various Load Requirements
Author(s): Mike Haydell
Abstract/Introduction:
Gas meters have become known as the CASH REGISTER of the natural gas industry. With todays competitive energy markets and the environment of FERC order 636, natural gas measurement has become an increasingly important issue. It is therefore the duty of measurement departments, to select equipment and design installations that are both efficient and economical.
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Document ID: 94BF2FAB

Meter Selection For Various Load Requirements
Author(s): Mike Haydell
Abstract/Introduction:
Gas meters have become known as the CASH REGISTER of the natural gas industry. With todays competitive energy markets and the environment of FERC order 636, natural gas measurement has become an increasingly important issue. It is therefore the duty of measurement departments, to select equipment and design installations that are both efficient and economical.
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Document ID: 5F15A3FF

Sampling And Conditioning Of Natural Gas Containing Entrained Liquids
Author(s): Donald P. Mayeaux
Abstract/Introduction:
Hydrocarbon liquids, entrained in natural gas, have been the source of many sampling problems. The primary problem is lack of agreement in the natural gas industry on the fundamental issue of should entrained liquid be included or excluded from sample gas. Standard practices issued by industry organizations are generally more applicable to natural gas that is free of liquid. The current standard practices provide minimum guidance in dealing with entrained liquids. Most of the current research in this field relates to techniques for sampling rich gas sources that contain no liquid.
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Document ID: 6D099405

Maintaining And Troubleshooting Chromatograph Systems
Author(s): Mark W. Smyth
Abstract/Introduction:
of instrumentation, only one of which is the gas chromatograph. Contractual requirements frequently define the energy content, relative density, and moisture content of the gas being sold. The sale of natural gas is performed on the basis of the heating value per unit volume of the gas. For these reasons, the industry uses instruments to monitor the quality of the gas at the point of sale or at strategic locations along a pipeline. The following instruments are commonly found in the field and in the laboratory:
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Document ID: F5D14EFA

Gas Flow Conditioning
Author(s): Michael P. Saunders
Abstract/Introduction:
The full cost of ownership consists of the initial capital, commissioning, training, spare parts, maintenance and calibration costs for the lifetime of the equipment. The full cost is several times the initial capital investment and should be the deciding factor in equipment selection. The technical selection - accuracy, repeatability, drift, ease of calibration as well as reliability indirectly affects the cost of ownership. Proper installation and application of flowmeters are two of the most significant parameters in the measurement chain. These parameters influence the factors mentioned above and are neglected in most assessments. The misapplication of any device brings the wrath of field personnel on the operating companys engineering staff, as it should! More effort is required by the user community to match their expectations with reality. The selection, installation, operation and maintenance of quality equipment, if properly performed, are almost never discussed by operating personnel.
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Document ID: 16C3031A

Effects Of Entrained Liquid On Orifice Measurements
Author(s): William Johansen
Abstract/Introduction:
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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Document ID: 6DD62B49

Report On API Egm Standard
Author(s): Brent E. Berry
Abstract/Introduction:
Since this report references both itself and the 21.1 standard, the following nomenclature has been adopted to make it clear which document is being referenced. report - references this document, the one you are now reading. standard references the 21.1 standard, unless otherwise noted. section and subsection both refer to portions of the API 21.1 standard. document is a generic term that could be referencing either document. Hopefully the context will make it clear which document is being referenced.
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Document ID: 1BD82C54

Fundamentals Of Positive Displacement Diaphragm Meters
Author(s): Chris J. Berno
Abstract/Introduction:
A diaphragm meter is a positive displacement instrument which is used to measure the volume of gas that passes through it. This is accomplished through the known volume that is displaced for each stroke of the diaphragm. The diaphragm also provides the seal between the measuring chambers of the device. As such, the diaphragm meter has proven to be an accurate and reliable means of measurement of gas for many years. This is especially true at low flow rates because of its positive displacement characteristics. This paper includes a basic review of the function and design of the positive displacement meter as well as an explanation of the operation of the diaphragm meter.
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Document ID: 70B9B0A9

Automating Gas Measurement
Author(s): Richard L. Cline
Abstract/Introduction:
Since the discovery of oil and gas and the advent of commercial conveniences, which use oil and gas, companies have been confronted with the need to accurately measure the oil and gas bought and sold in the marketplace. And, as usual, the technology available at the time was brought to bear on the measurement process. All gas companies must, of course, deal with gas measurement and are positioned somewhere on the automation curve. As time moves forward, so does the technology. New products and measurement techniques are constantly being offered to improve the gas measurement process. Unfortunately, adopting the new technology always brings with it a price. And the price is not only measured in dollars, but in ever increasing difficulty in making intelligent decisions and choices. So how does a company, with the need to progress on the automation curve, sort through the many options available today? The effort requires a continuing education process. The decision maker must understand not only what the available technology can do for his company today but must understand its future impact on the company.
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Document ID: EE496E36

D.O.T. Requirements For Transportation Of Sample Containers
Author(s): Thomas F. Welker
Abstract/Introduction:
During my travels around the United States talking about sampling and sample containers, it has come to my attention that the oil and gas industry in the U.S. needs to be a little better informed on proper handling, shipping and transportation of sample containers of all types. Since everybody in the oil, gas and chemical industry seems to be involved in taking samples and handling sample containers, it behooves us to understand the laws and rules that govern their transportation. The Department of Transportation (D.O.T.) Title 49 covers the rules and regulations for the manufacture, handling and transportation of sample containers of all types. Whether you use specially-built sample containers, old homemade sample containers, old World War II oxygen bottles, gigantic sample containers, or very small cylinders, if you are transporting those sample containers in your vehicles or you are shipping them by common carrier and they have hazardous materials in them, you must be aware of the rules that govern the handling of those cylinders.
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Document ID: 61FD2133

D.O.T. Qualification Of Pipeline Personnel Rule
Author(s): Jesus Ramos
Abstract/Introduction:
More than a decade ago the federal government began the process of additional regulation for the natural gas and hazardous liquids industry requiring operators to train employees who work on their pipelines. Since then, the industries have anxiously waited for what may every well be an expensive and significant rule imposed on the gas transmission/distribution industry and hazardous liquids pipelines. The gas and liquids industries and the feds may have finally resolved the issues and agreed in principle on a rule that will require gas employee qualification, not to be confused with to employee training, while promoting its intent, safety. The process involved federal register notices, industry comments, numerous negotiating meetings, then government, public, and pipeline industry acceptance. Now the gas industry needs to understand the proposed rules purpose and how to comply without incurring major expenses.
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Document ID: 5C6FA7BA

Application For Telemetry In Gas Transmission An Overview Of Scada And Telemetry, And Its Use In The Transmission System
Author(s): Joe L. Martine
Abstract/Introduction:
This paper will present the basic concept of Telemetry and how it applies to SCADA systems. Lets start with what is Telemetry? Telemetry can be defined as the process of where data from a measured device is being transmitted to a distant location by any variety of media, e.g. radio, telephone, etc., which leads us to what is SCADA? The acronym stands for Supervisory Control And Data Acquisition. A Supervisory Control system is a system that has the ability and intelligence to perform controls with minimal supervision And a Data Acquisitions system has the ability to gather data. SCADA systems are specialized systems used to monitor and control facilities from a remote location. They are commonly used in the gas, oil, electric, and water transmission and distribution industries where facilities are stretched out over a large area.
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Document ID: A5673EE3

Problems Unique To Offshore Measurement
Author(s): Wayne T. Lake
Abstract/Introduction:
As the worldwide demand for oil and gas forces offshore exploration into waters off the continental shelves into depths of over a mile deep, capital expense spending (CapEx) and production operation expense (OpEx) budgets are slashed and the Environmental Health and Safety (EH&S) requirements as well as some companies goals for a greener image raises the standards of operations even higher, the demands placed on accurate hydrocarbon measurement with minimal maintenance, space and weight requirements becomes increasingly greater. These financial, governmental and technical challenges coupled with normally high flow rates and therefore wide flow range requirements have enhanced the development and application of new technology such as ultrasonic gas and liquid meters, multiphase flow meters, microwave and near infared (NIR) water cut analyzers, coriolis flow meters for oil and gas and compact orifice meter tubes utilizing isolating flow conditioners and liquid meter provers. This paper will attempt to provide guidelines in selecting, installing and operating this equipment to insure cost effective designs and reliable operation with a high degree of accuracy. Since the authors background is primarily in project design, emphasis will be placed on the decision process of selecting, installing and commissioning metering equipment.
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Document ID: 7AF3064B

Terminology Used In Instrument Accuracy
Author(s): Rick Williams
Abstract/Introduction:
The purpose of this paper is to offer a brief explanation and discussion of many key terms used in describing instrument accuracy. The terms included within this discussion are most commonly used for defining performance standards with primary sensing elements typically used in the measurement of flow, level pressure and temperature instruments. Many of the terms used may apply to controllers, recorders and final control elements. However, the focus provided herein is the primary element device. The specific devices include transmitters (differential pressure and temperature) and flow meters (e.g. magnetic, vortex, turbine, variable area and positive displacement). This paper is written for the benefit of the typical user of instrumentation products to include instrument engineers and technicians. A comprehensive discussion of precision measurement must address calibration and traceability issues. The scope of this paper will be limited to discussing the terms associated with the application of instruments rather than addressing the issues of maintaining accuracy. Calibration is a key issue in determining the continuous performance of an instrument and is worthy of discussion. However, it is complex enough to warrant separation from this discussion.
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Document ID: D448C6F1

Field Experience With Electronic Calibrators
Author(s): Leo J. Buckon
Abstract/Introduction:
The use of electronic pressure calibrators in the gas industry has added new concerns and issues in pressure measurement. With the onset of electronics, new and strange words began appearing. Readings and terms appeared that perhaps didnt match the old reliable standby calibration readings or methods. Terms like sensitivity, accuracy, resolution, stability, and traceability surfaced. Technicians began using correction factors to achieve standard conditions. These correction calculations gave the technicians challenges when performing their calibrations. Technicians began seeing the effects of temperature on their test instruments and how temperature effects the accuracy of the gas measurement. This paper will look at the selection and use of electronic pressure calibration equipment. Technicians will find that these instruments will make their job easier if they look carefully for instruments that are traceable, precise, accurate, sensitive, and repeatable. The American Petroleum Institute Chapter 21, offers good advice and recommendations for selecting electronic instruments.
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Document ID: C7067888

Traceability Of Test Instruments
Author(s): Leo J. Buckon
Abstract/Introduction:
Is a measurement being made good and is it as good as the measurement that was made yesterday, a week ago, or a year ago? The question of what is good measurement is asked all the time. This paper reviews what constitutes a good measurement. In addition it discusses the means that have been established to give the individual doing the measurement confidence that it is a good measurement. First, it discusses test instrument selection. The paper looks at characteristics of a test instrument such as accuracy and repeatability. It discusses the effect of temperature on accuracy and how traceability is important to the ultimate goal of making a good measurement. Second, it looks at the measurement process and the factors that influence the collection of data for measurement assurance. Finally, it reviews both National and International Standards for maintaining documented traceability
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Document ID: 97C06ABA

Low Power Flow Computers
Author(s): Larry A. Quick
Abstract/Introduction:
Flow computers are specially designed micro-processor controlled CPUs specifically constructed to collect, calculate, store, and transmit flow measurement data to a host system along with audit trail and alarm information. They are an essential part of electronic fluid flow measurement, and are usually installed in various remote locations throughout the oil and gas production, transmission and distribution industries. The primary use of a flow computer is to measure the transfer of a fluid from one point to another, however, most flow computers are now able to execute limited flow control commands also. All the flow computer functions are controlled by on-board firmware, sometimes in conjunction with inputs from the host system. It is this on-board firmware, and associated host software, that allows the user to maximize the flow computers versatility and efficiency. Since flow computers measure (and as just stated, sometimes control) the transfer of ownership of a flowing fluid, they are essentially the cash registers of the oil and gas companies.
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Document ID: 9E6C34C3

Economics Of Electronic Gas Measurement
Author(s): Tom R. Cheney
Abstract/Introduction:
In todays world we almost accept computers without question. In fact we place our hard-earned dollars and in some cases even our very lives in their care without a second thought. Computers and electronic technologies have greatly impacted the way everyone does their business. For those of us who work in the oil and gas industry, the use of electronic gas measurement devices (EFM) is an example of this impact. With the use of the EFM, and associated electronic equipment, we not only have the option to measure gas volumes but to retrieve required data instantly and enhance production through well automation. As in any business, before the decision is made to upgrade or change from the standard method of measurement using the typical dry flow chart recorder, the economics of such a decision needs to be evaluated. You will find that the economic justification of using EFM is often difficult to quantify.
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Document ID: 8724BA56

Fundamental Principles Of Rotary Displacement Meters
Author(s): Ron L. Strong
Abstract/Introduction:
Natural gas measurement today is accomplished through the use of two different classes of gas meters. These are inferential type meters, which include orifice and turbine meters, and positive displacement meters, which include diaphragm and rotary displacement meters. The inferential type meters are so-called because rather than measuring the actual volume of gas passing through them, they infer the volume by measuring some other aspect of the gas flow and calculating the volume based on the measurements. The positive displacement type meters are so-called because they measure the actual volume of gas displaced through them. The rotary positive displacement meter has been in existence for over 75 years. Its reliability, rangeability, longterm accuracy, and ease of installation, maintenance and testing have made this meter a favorite among gas utilities for billing purposes in industrial and commercial applications. Rotary meters have also gained popularity in the production and transmission markets.
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Document ID: 53E43192

A New Perspective On Measurement
Author(s): Lohit Datta-Barua
Abstract/Introduction:
Everything we do must have business relevance or must add value. This is true not only for measurement process, but for every process we are involved in. One must constantly question our action and not fall in the trap of thats the way we have always done it. This paper provides a new perspective on measurement in light of changing business environment, competition, and technology. We have heard words such as Measurement is the cash register, Measurement is a necessary evil, Measurement is an inexact science, etc., and there may be some truth in them. We recognize that new technology and a new business environment have complicated our lives, yet our overall view remains very narrowly and technically focused. Measurement gurus talk about the technical defensibility of what we do without taking responsibility for its economic impact. We revise technical documents, and we get carried way with the best accuracy at any cost. We apply the latest and greatest supercompressibility calculations to six decimal places to calculate a few MCF of gas flow through an oversized meter run that has not been checked in a long time. The bottom line is: We cannot see the forest for the trees.
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Document ID: 970AAAE3

Qps, Oq And You
Abstract/Introduction:
OPS (Office of Pipeline Safety) and its State partners have been undergoing changes in their approach to pipeline safety compliance. You will notice the word enforcement is not used as much as in the past. OPS is interested in compliance through a working relationship between the operator(s) and regulatory bodies. OPS has undergone much scrutiny, soul searching, and mindset changes, in an effort to promote and assure better safety of pipeline systems without increasing the burden on the operator(s). All of the studies and evaluations brought about a new paradigm. Through partnering and stakeholder approaches, Risk Management (RM) and System Integrity Inspection (SII) programs were developed. With changing times and the competitive market place, OPS and its partners must do business differently. It is no longer acceptable to follow a check list blindly and count number of violations. Inspectors will have to dig deeper and become more acquainted with the operations of the pipeline system(s). A mutual trust between the operator and inspector must be established in order for the program to be successful. Much more detailed data must be shared in order to get by in the regulatory community. The regulatory community must assure trade secrets are not compromised. The communication phase is well under way with some programs that will be implemented shortly.
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Document ID: CB21714A

Training Gas Measurement Personnel
Author(s): A. S. Buddy Harris, Jr.
Abstract/Introduction:
Todays technology in the field of gas measurement is constantly changing, and the training of its measurement technicians is of the utmost importance. These technicians must be continually educated in order to possess the most current knowledge of the latest equipment on the market today. Also, it is essential that this type of instruction should be taught in a controlled environment where the technicians can learn and develop the necessary skills with the least amount of interruptions from external sources.
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Document ID: 0482301A

Lessons Learned From The API 14.1 Gas Sampling Research Project
Author(s): Kendricks A. Behring II
Abstract/Introduction:
Natural gas sampling is a process critical to the measurement of gas value. Improper sampling can distort the composition of natural gas, which indirectly affects flow rate measurement through gas properties and directly impacts heating value measurement. Thats why the American Petroleum Institute (API) Manual of Petroleum Measurement Standards (MPMS) Chapter 14.1 working group initiated a consortium research project - to document the causes of gas sample distortion and to implement procedures that work. The working group will use these research results to revise the industry standard for gas sampling, the API MPMS Chapter 14 - Natural Gas Fluids Measurement, Section 1 - Collecting and Handling of Natural Gas Samples for Custody Transfer 1. The project is funded by the Gas Research Institute (GRI), API, and the U.S. Minerals Management Service (MMS), and is being performed at the GRI Metering Research Facility (MRF) at Southwest Research Institute (SwRI) in San Antonio, Texas. Equipment manufacturers have also provided support for the project. An interim GRI technical report 2 has been published to summarize work completed in 1997.
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Document ID: FBC474C7

Pulsation Reduction By Acoustic Filters For Metering Applications
Author(s): Robert J. Mckee
Abstract/Introduction:
Because of the adverse effects of pulsations on orifice and other types of flow meters there is for many installations, a need to eliminate or decrease the amplitude of pulsations in the piping. This task has been the primary domain of acoustical piping designers who have had both theoretical and practical field experience in such areas. The most common and effective treatment for pulsation control is the design and installation of acoustic filters. However, most filters designed by novices are not effective and are costly to operate because of pressure drop losses. This paper discusses the basic principles and considerations in acoustic filter design. There are many small compressors such as well-head gathering compressors that cannot justify the cost of a thorough acoustic analysis in order to protect the nearby orifice meter from excessive pulsations and accompanying square root error. This paper will make an effort to demonstrate design procedures related to a specific type of acoustic filter to be used to reduce pulsations in most simple metering applications. The specific filter is a symmetrical in-line low pass filter.
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Document ID: E7E55C58

Pulsation Effects On Orifice Metering Considering Primary And Secondary Elements
Author(s): Robert J. Mckee
Abstract/Introduction:
The use of orifices for commercial flow measurement has a long history dating back more than 50 years. Orifices are extensively used in the United States natural gas, petroleum and petro-chemical industries and are important as one of the most practical ways to meter large volumes of gas flow. These meters are very reliable and cost effective and if properly used, can be relied upon to give accurate results. Proper use normally requires the steady flows for which orifices were intended and for which the orifice coefficients were developed. In actual field installations, flow is often not steady but subject to the periodic changes in pressure and velocity that are referred to as pulsation. Pulsation can be caused by compressors, pressure regulators, control valves, fluctuating loads, or by flow-induced phenomena within the piping. It is known and well recognized that pulsation causes errors in orifice meter results. In fact, A.G.A. Report No. 3 on Orifice Metering of Natural Gas, which is also ANSI/API 2530, clearly states that: Reliable measurements of gas flow with an orifice cannot be obtained when appreciable pulsationare present at the measurement point.
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Document ID: 1C0BB49F

An Overview Of A.G.A. Report No. 9 Measurement Of Gas By Multipath Ultrasonic Meters
Author(s): Charles W. Derr
Abstract/Introduction:
The American Gas Association has published (June, 1998) a recommended practice Report No. 9, Measurement of Gas by Multipath Ultrasonic Meters. This paper reviews some of the key contents of A.G.A.-9 including recommended meter performance requirements, design features, testing procedures, and installation criteria. The topic selected for this paper was chosen based upon the questions most commonly asked of some ultrasonic meter vendors. A.G.A-9 was drafted by the A.G.A. Transmission Measurement Committee which incorporated many of the recommendations in the GERG Technical Monograph 8 (1995) and certain related OIML recommendations. After more than one year of technical discussions, balloting, and revisions, the document represents the consensus of several dozen metering experts in the US and Canada. It is hoped that A.G.A.-9 will soon be considered by ISO/ TC 30 as the basis for a new ISO standard.
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Document ID: 58022173

Transient Lightning Protection For Electronic Measurement Devices
Author(s): Patrick S. Mccurdy
Abstract/Introduction:
Technology advances in the world of semiconductors and microprocessors are increasing at a breathtaking pace. The density of transistor population on integrated circuits has increased at a rate unimaginable just a few years ago. The advantages are many: faster data acquisition, real time control, and fully automated factories, to name a few. Semiconductor technology is also prevalent in field mounted instrumentation and electronic measurement devices. Unfortunately, a tradeoff to the increased performance is the susceptibility of these semiconductor devices to voltage and current transient events. The minimum results are unreliable instrumentation readings and operation, with periodic failures. The worst case result is a completely destroyed measurement device. Such power surges are often the work of mother nature. Lightning, which according to the National Weather Service strikes some 40 million times annually in the U.S., is a leading cause of failure in electronic measurement devices. When these devices are field mounted the vulnerability greatly increases due to their remote location and outdoor installation.
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Document ID: 97591489

Communication Between Office And Field
Author(s): Duane A. Harris
Abstract/Introduction:
The gas industry today is constantly changing, with increasing demands on office and field personnel. Initially there was FERC (Federal Energy Regulatory Commission) Order 636 that forced the gas measurement departments into the electronic age. Next came corporate slashing that has required the gas measurement groups to perform at the same level of integrity in measurement with reductions in staff of up to 60%.Then GISB (Gas Industry Standards Board) made its way into the gas measurement department through proposed standardization. To meet these demands requires timely communication between the office and field employees. Both of these locations (field and office) have been impacted with increased work loads and constant upgrades in equipment and software. With all of this occurring, it is very easy to overlook one of the key links to accurate measurement and that is communication.
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Document ID: F7D770ED

Audit Of Efm Measurement
Author(s): Jack Chisum
Abstract/Introduction:
INSTALLATION The EFM (Electronic Flow Meter) includes an AGA approved meter tube. The tube installation must meet AGA guidelines. This tube must be clean and the orifice must be center with sharp edges. This is a minimum requirement for the correct measurement of any fluid. The gauge lines must be installed to keep the any liquid from entering into the manifold which would then cause and incorrect reading by the EFM. The installation must be free from excess vibration or pulsation.
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Document ID: 2A1B9452

Gas Measurement By Insertion Turbine Meter
Author(s): Larry A. Quick
Abstract/Introduction:
The gas industry has had a requirement for many years for a simple and reliable cost-effective meter to measure gas flow in large diameter pipes, or even in smaller diameter pipes in which the flow cannot be interrupted or the passage obscured. The insertion turbine meter is well suited for this type of flow measurement in a variety of non-custody transfer applications. It is presently used in many applications such as compressor efficiency and surge control, pipeline catastrophic leak detection, pacing odorizers, pacing samplers and checking throughput. There are several commonly desired features associated with the use of an insertion turbine meter. Linearity and repeatability are usually the most important features. Rangeability can be just as important in most applications. Fast response time, negligible pressure drop across the sensing device and easy removability under pressure are usually given requirements for any application considering the use of an insertion turbine meter. Of course in todays business environment, reliability, simplicity of use and economical are absolute given requirements for any product or service being supplied.
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Document ID: 97EBEB86

Chart Auditing
Author(s): Gary P. Menzel
Abstract/Introduction:
Auditing of measurement stations is critical to insure proper credit for gas produced and sold. Our experience has shown that over 3% of months audited on chart measurement stations have problems, which result in a measurement adjustment. Return on investment in auditing should be greater than two to one. If properly installed check measurement exists and is used to select those stations for which a full audit is performed, the return may be a high as ten to one, not including the ongoing cost of the check measurement, or four to one including such costs. Therefore failing to properly audit can result in substantial profit loss for your company. There are benefits to auditing above the direct increase in revenues associated with retroactive measurement adjustments. Verification of your own measurement procedures, identification of certain operational problems and correction of conditions, which result in poor measurement, are among these benefits. Also, there is the difficult to quantify effect, that once a problem is identified in the audit process and corrected, the same problem does not continue in following months, though it may re-occur. There may be a reduction in the number of mistakes occurring after an audit program begins, since no one likes someone else finding their mistakes.
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Document ID: BC0B43B0

Gas Contracts: Making Gas Contracts Simple
Author(s): Tom Cleveland
Abstract/Introduction:
Contracts involving the sale, gathering, transportation, processing, storage, marketing, compression, and other services provided by the typical natural gas organization are crafted with contributions from several different functional groups and individuals. The expertise of these different groups and individuals is needed to put into writing an agreement that will allow an organization to invest capital in projects with known risk and expected rate of return and to carry on with the day-to-day business activities it was formed to do. This paper will discuss the various elements of typical natural gas contracts and the expertise called upon to draft these elements.
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Document ID: DF00B93E

Operation Of Orifice Meter Chart Integration
Author(s): Gary L. Hammond
Abstract/Introduction:
The EMC Chart Integrator, Model 362, is a digital computer based system for translating orifice meter chart records into accurate billing-compatible data on integrated flow (chart extension), average pressure and flow time. It is designed to accommodate American/Barton and Foxboro charts, as the pens can be mounted so as to pivot in the same geometric paths as the recording pens of these types of meters. As an option, the Chart Integrator can be fitted with pens for a third chart geometry if required. The operator places the Chart Integrator pens on the appropriate lines on the orifice chart while applying pressure to the foot control, the chart will begin to rotate. The rotation and motion of the pens simulate the action of the meter. At the end of the chart the Chart Integrator computes and prints the extension, pressure and flow time for that recording. The operator will then place the chart into the printer and the chart extension, average pressure, flow time and current date will be printed onto the back of the chart for validation. At chart validation the extension and the number of charts validated are recorded in the Chart Integrators memory as a batch total. This batch total can be printed and cleared upon demand by the operator at any time.
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Document ID: 27A565BB

Methods Of Gathering Egm Data
Author(s): Stephen Easley
Abstract/Introduction:
Todays changing world of computers and data communications is an exciting time and is bringing major changes to the gas industry. Especially when evaluating whether to communicate with remote electronic gas measurement (EGM) devices and determining what communications media types will be installed.
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Document ID: 76766166

Cellular Digital Packet Data Technology For Scada And Telemetry Applications
Author(s): Bob Halford
Abstract/Introduction:
The introduction of Cellular Digital Packet Data technology (CDPD) came about after the build out of the cellular voice systems in the United States. The designers of those systems realized a part of that technology was not being used that could send short burst packets of data without interfering with the voice transmissions. The definition of CDPD would be: CDPD is a technology intended to provide packet data networking services to mobile hosts. The method used consists of radio channels typically used for Advanced Mobile Phone Systems (AMPS) cellular service.
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Document ID: 37AA527D

Overall Measurement Accuracy
Author(s): Tom Cleveland
Abstract/Introduction:
The measurement of hydrocarbon fluids, with an overall measurement accuracy that is acceptable to all involved parties, is a goal most gas measurement organizations strive to meet. The achievement of overall measurement accuracy can be visualized by using an image of a steel chain. One side of the chain is fastened to the true quantity that passes through a measurement point. The other side of the chain is fastened to the observed quantity passing through the measurement point. If all of the links of this theoretical chain are strong, the observed reading will be held very close to the actual reading. If there are weak links in the chain, a difference in the true reading and observed reading will be experienced.
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Document ID: 459BBD9C

Requirements Of An Egm Editor
Author(s): Michael Squyres
Abstract/Introduction:
The natural gas industrys adoption of EGM as a means of increasing the speed and accuracy with which measurement information is obtained, has created the need for an electronic data management system. These systems, if not properly designed and implemented, could potentially render the entire process useless. Therefore, it is essential that the system add functionality that complements the power of the hardware. With proper implementation, such a system will not only facilitate operations in todays fast paced, post-FERC 636 environment, but also will establish a foundation for meeting tomorrows measurement challenges. A good EGM data editing software package should provide a suite of tools to facilitate accurate, timely data processing. It should do this in a structured, feature rich, well designed environment utilizing a graphical user interface (GUI). The program should include functions to do the following: import the data recognize, review, and correct anomolies report export and provide advanced ad hoc query capabilities. Other considerations should include the developers commitment, resources, and long term strategy, vis-a-vis electronic gas measurement, as well as industrys overall acceptance of the package.
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Document ID: CACF54EA

From Pen Tip To Volume Statement
Author(s): Jodie Splawn
Abstract/Introduction:
Accurate and reliable gas measurement depends on a combination of efforts from two groups of people. First, we have the field personnel. They have the responsibility of seeing that a readable chart is produced and that all information pertinent to volume calculation is supplied to our next group, which is the office personnel. This group will read the chart, apply information supplied by the field, calculate the amount of gas delivered, and generate and deliver volume statements to the customer. It must be recognized that the office group can not calculate volumes until it receives the charts and other required data from the field, and that the volumes are only as accurate as the data received. With this in mind, lets look at the two separate groups and see the team effort involved in producing accurate and reliable measurement from Pen tip to Volume Statement.
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Document ID: AE1FC507

Ultrasonic Gas Flowmeters For Check And Custody Transfer
Author(s): Jim Micklos
Abstract/Introduction:
This paper presents an outline of the theory and methods applied in ultrasonic gas flow metering for check and custody transfer. The development of single and multipath instrument for custody/noncustody will be discussed, also recent developments will be indicated. Practical applications are illustrated using the Instromet 1-path check and 3-path / 5-path Q.Sonic custody transfer flowmeters.
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Document ID: 7DA9A567

Fundamentals Of Pressure Regulators
Author(s): Rick F. Mooney
Abstract/Introduction:
A Pressure Regulator is a device that controls the flow of gas from a higher pressure system to a lower pressure system while attempting to maintain a constant system pressure. Pressure regulators are used throughout the gas industry to control the many different pressures used to move gas from production wells to the point of use in home and industry. The two main types of regulators used in the gas industry are pressure reducing regulators which control the flow of gas to maintain downstream pressure, and back pressure (relief) regulators which control upstream pressure. Both types of regulators are also used as over pressure protection devices as monitor regulators and relief valves to prevent the system at the lower pressure from being over-pressured. These types of regulator are available in two designs: Self Operated and Pilot Operated. A good understanding of each type and design is necessary to oversee the operation, maintain, or trouble-shoot these devices.
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Document ID: B1725E9E

Fundamentals Of Natural Gas Safety
Author(s): Linton T. Lipscomb
Abstract/Introduction:
Natural Gas: A combustible mixture of methane and higher hydrocarbons used chiefly as fuel and raw material. To safely produce natural gas and natural gas products, a basic understanding of the hazards of the material itself and the processes required to bring it to market is essential. Lets start out with the hazards of natural gas as it is in its raw field gas state: 1. Flammable/Explosive 2. Hazardous Impurities a. Hydrogen Sulfide b. Benzene c. CO2 d. Liquid, Petroleum Gases (LPGs)
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Document ID: AE0C16B8


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