Measurement Library

Western Gas Measurement Short Course Publications (2005)

Western Gas Measurement Short Courses

Troubleshooting Regulators And Control Valves
Author(s): Paul R. Adams
Abstract/Introduction:
This paper will address the gas pressure reducing regulator installation and the issue of erratic control of the downstream pressure. A gas pressure-reducing regulators job is to manipulate flow in order to control pressure. When the downstream pressure is not properly controlled, the term unstable control is applied. Figure 1 is a list of other terms used for various forms of downstream pressure instability. This paper will not address the mathematical methods of describing the automatic control system of the pressure reducing station, but will deal with more of the components and their affect on the system stability.
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Document ID: F9D58C9D

How Todays Advanced Ultrasonic Meter Diagnostics Solve Metering Problems
Author(s): John Lansing
Abstract/Introduction:
This paper discusses both basic and advanced diagnostic features of gas ultrasonic meters (USM), and how capabilities built into todays electronics can identify problems that often may not have been identified in the past. It primarily discusses fiscal-quality, multi-path USMs and does not cover issues that may be different with nonfiscal meters. Although USMs basically work the same, the diagnostics for each manufacturer does vary. All brands provide basic features as discussed in AGA 9 Ref 1. However, some provide advanced features that can be used to help identify issues such as blocked flow conditioners and gas compositional errors. This paper is based upon the Daniel USM design and the information presented here may or may not be applicable to other manufacturers.
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Document ID: 39D5349E

Introduction To Electronic Volume Correctors
Author(s): Curtis Cowell
Abstract/Introduction:
Electronic volume correctors (EVC) are an essential part of gas measurement departments. The purpose of the volume corrector is to calculate corrected volume of natural gas through meters. The device is used to compensate for changes in actual operating conditions of the gas system. In this paper we will cover the aspects involved in calculating and configuring electronic volume correctors.
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Document ID: A9F8BD10

Differential Testing Of Rotary Meters
Author(s): Wayland Sligh
Abstract/Introduction:
Rotary meters have been around for approximately 80 plus years. They were first made by Roots Brothers. The first design was rather simple compared to todays designs. Today rotary meters can measure gas from 2 to 3 cubic feet per hour through 160,000 cubic foot per hour. The range covers residential, commercial, all the way to large industrial pressure ratings available through 1480 psi. This paper will discuss methods of testing, differential pressure testing & prover testing.
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Document ID: 92142FAD

Field Proving
Author(s): Phil Whittemore
Abstract/Introduction:
This paper provides a basic overview of the different test methods most commonly used in the natural gas industry for testing commercial and industrial capacity gas meters, with a more comprehensive review on the theory of transfer proving and recommended operational procedures. All meters need to be tested for accuracy. Many companies remove their larger meters from service and take them into the shop for test and repair, while others find it is more economical to test their large meters on location at the meter site. Greater emphasis on accurate measurement by gas companies has enhanced the need for better methods of field testing meters.
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Document ID: 4E1959D3

Fundamentals Of Gas Turbine Meters
Author(s): John A. Gorham
Abstract/Introduction:
The majority of all gas measurement used in the world today is performed by two basic types of meters, positive displacement and inferential. Positive displacement meters, consisting mainly of diaphragm and rotary style devices, generally account for lower volume measurement. Orifice, ultrasonic and turbine meters are the three main inferential class meters used for large volume measurement today. Turbines are typically considered to be a repeatable device used for accurate measurement over large and varying pressures and flow rates. They are found in a wide array of elevated pressure applications ranging from atmospheric conditions to 1440 psig. Turbine meters have also become established as master or reference meters used in secondary calibration systems such as transfer provers. A significant number of both mechanical and electrical outputs and configurations have become available over the past 50 years of production. This paper will focus on the basic theory, operating principles, performance characteristics and installation requirements used in turbine meter applications. A discussion of fundamental turbine meter terminology is also included.
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Document ID: 10ADA593

Ultrasonic Meter Station Design
Author(s): Stephen T. Stark
Abstract/Introduction:
Of the many types of gas meters available today, ultrasonic meters remain a popular choice among gas companies and others for strategic measurement applications including custody transfer. Often used for larger pipeline deliveries, ultrasonic meters measure many millions of dollars of gas every day, so their accuracy and reliability is very important. Ultrasonic meters are capable of providing excellent results when they are installed in properly designed meter stations that are also carefully constructed and maintained. It is important to remember that an ultrasonic meter is but one part of a meter station.
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Document ID: 84CC0B00

Fundamentals Of Multi-Path Ultrasonic Meters
Author(s): William R. Johansen
Abstract/Introduction:
The use of sound waves to measure fluid flow was conceived more than 40 years ago. The basic equation for measuring flow using sound waves will be discussed and derived. An understanding of velocity profiles is also important as the velocity profile of the gas flowing in a pipe will affect the accuracy of ultrasonic flow measurement. Most ultrasonic flowmeters in use today are flow calibrated. An understanding of how the ultrasonic meter is to be used in the field is essential in establishing calibration parameters. As a result of a flow calibration the ultrasonic meter is adjusted to bring it into agreement with the calibration facility. Three different methods of adjusting ultrasonic meter performance are currently in use. The three different adjustment methods will be discussed as well as the potential strengths and weaknesses of each.
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Document ID: 89B673B4

Essentials Of Meter Station Design
Author(s): James L. Robertson
Abstract/Introduction:
So much of meter design is driven by the struggle between cost and accuracy. Improved accuracy requires more cost. Further, accuracy is subject to the law of diminishing returns. To achieve an increment of increased accuracy (or equivalently an increment of decreased uncertainty) requires an ever increasing expenditure. Station capacity and accuracy requirements determine meter selection, ancillary equipment, and station design. This article gives a brief description of the primary types of custody transfer meters and the design requirements to meet specified measurement uncertainty. It also examines a few operational meters and looks at their practical field installed uncertainty.
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Document ID: B2DC5769

Introduction To Gas Metering
Author(s): Jeff Webb
Abstract/Introduction:
It is crucial for a gas company to have properly designed metering stations at every receipt and delivery point. Without them, it would be impossible to know how much gas is being taken into your system, how much each customer is using, and how much is being lost. These meters allow the gas company to track receipts, forecast loads, and bill customers for the gas sold. Unlike electricity that incurs losses as it travels through conductors, gas networks are designed to be closed systems. So what goes in, must come out with the obvious exceptions of leaks and relief valves. This paper will introduce the two categories and five common types of cash registers most often used in the gas industry today. The two categories of meters are Positive Displacement and Inferential, and the five types are Diaphragm, Rotary, Orifice Plate, Turbine, and Ultrasonic. Positive Displacement Inferential Diaphragm Orifice Plate Rotary Turbine Ultrasonic Positive displacement meters have precisely designed chambers that allow a defined amount of gas to pass through them. The gas measurement is based upon how many times the chamber is filled and emptied. Inferential meters have no chambers or compartments to fill and empty. Instead, the flow rate is based on the measurement of a physical characteristic.
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Document ID: 6E36E64A

Fundamentals Of The Basic Gas Laws
Author(s): Robert Bennett
Abstract/Introduction:
Science interprets nature in terms of matter and energy. Energy is defined as the capacity to do work. There are many types of energy such as heat energy, electrical energy, kinetic energy (energy of motion), and potential energy (intrinsic energy of an object due to the position of the object). Matter is the material of which the universe is composed and is defined as anything that occupies space and has mass. There are three normal states of matter - solid, liquid, and gas. Under certain conditions, most substances can be made to exist in any of the three states, i.e. water as steam, liquid, or ice. Solid matter is rigid, generally crystalline, and will exhibit a definite shape. Liquids will flow, assume the shape of the container they are stored, and considered to maintain a constant volume and density. Gaseous matter is much more difficult to qualify since it consists of widely separated molecules in rapid motion. The comparatively large distances between the molecules make it possible for one gas to accommodate molecules of another gas or be compressed to force the individual molecules closer together. Since the molecules are in constant motion, they will expand to fill any container and strike the walls of the vessel. These myriad impacts result in a pressure.
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Document ID: 1B39B55F

Regulator Station Design
Author(s): Rick F. Mooney
Abstract/Introduction:
The design of gate station, district regulator and high volume end-user regulator stations requires planning and consideration of many environmental and application issues. This paper will focus on the basic design practices and special considerations for these three types of regulating stations in the natural gas industry. Whether the station is designed to control flow, pressure or simply measure gas, before beginning any project it is important to gather as much application information as possible.
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Document ID: BB68633B

Radio Frequency Identification - Rfid
Author(s): Terry Mohn
Abstract/Introduction:
Radio Frequency Identification is an increasingly economical technology that improves the ability for an organization to track and identify materials and equipment. The Southern California Gas Company recognizes that RFID can help them reduce or eliminate lost meters, improve supply chain efficiencies, and improve inventory control and material processing. Knowing where every item is means saving huge percentages of the labor that makes up the bulk of supply-chain cost as well as knowing whether an item was properly accounted for when it was placed into service. Significant revenue improvements will result by optimizing material management using this technology.
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Document ID: 6D77AFA8

Onsite Proving Of Gas Turbines
Author(s): Daniel J. Rudroff
Abstract/Introduction:
With the increased use of Natural Gas as a fuel, higher natural gas prices, and the new federal regulations, buyers and sellers of natural gas are seriously looking at ways to improve their natural gas measurement and reduce the unaccounted for natural gas. An error in measurement of only one tenth of one percent (0.1%) on 100 MMSCF/D Natural Gas selling at 5.50/MCF will cause an over or under billing of 200,750.00 in one year. This will more than pay for a proving system. If the company undercharges it has lost money and if it over charges it has the risk of lawsuits later for huge amounts of money. The Btu in one barrel of oil for example is equivalent to approximately 5,600 cubic feet of natural gas. At 6.50 per thousand cubic feet, the natural gas equivalent of one barrel of oil is 36.40 equal to, or more than the cost of a average barrel of oil. In the petroleum liquid industry no custody transfer liquid measurement system would be complete without a method to prove the meter, either as part of the equipment or there would be connections provided for a portable prover. Under billing causes loss of revenue, and over billing can cause a future correction that will cost the company millions of dollars. For these reasons gas meter proving is important and necessary to insure precise measurement of natural gas that both the buyer and seller can agree upon. In the ASME standard MFC-7M-1987 Reaffirmed 2001 Measurement of Gas Flow by Means of Critical Flow Venturi Nozzles it is stated The Venturi nozzles specified in this Standard are called primary devices. Nozzles have been used for many years to prove natural gas meters. Sonic Nozzles have a long history, are well documented and the formulas, although a bit complicated, are in most flow computers.
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Document ID: 08E2D211

Curb Meter Development
Author(s): Murray Royce
Abstract/Introduction:
The new American Meter Curb Meter is the result of a joint development between the Sempra Utilities and American Meter Company. Individuals within the two companies sought to provide a solution to an increasing demand for a curb meter replacement. Several options were considered and this is an account of the chosen meter design and its evolution. The new design curb meter Some Western Gas Measurement Short Course members, particularly those residing in the northern climates, may not be all that familiar with curb meters. These are 200, 400 and 600 cfh series meters that are traditionally cast iron, diaphragm style units with side connections and most importantly, top reading indexes. They are set within a subterranean vault, usually close to the street or curb. Inside the vault is the inlet line, shut off valve, regulator, meter and associated piping. The vault will have a removable top with an access door for the reading of the index. A curb meter vault can be a cool, dry and protected place to locate a meter or it can be a flooded, dirt filled, wet and corrosive nightmare. The resulting deterioration of the meters found in the latter situation can be quite severe.
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Document ID: 57ED13E4

Coriolis Mass Flow Meters
Author(s): Karl Stappert
Abstract/Introduction:
Coriolis meters have gained worldwide acceptance in liquid applications since the early 1980s with an installed base or more than 350,000 units. Newer designs have shown greatly improved low-flow sensitivity, lower pressure drop, and immunity to noise factors which now enable their successful use in gas-phase fluid applications. With more than 20,000 units on gas around the world, measurement organizations around the world are involved in writing standards for this emerging gas flow technology.
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Document ID: 2460EE97

API Mpms Chapter 14.1 Natural Gas Sampling Standard Changes( Due To Research Findings)
Author(s): Fred G. Van Orsdol
Abstract/Introduction:
In the late 1980s, producing companies were working with the Bureau of Land Management (BLM) to produce workable regulations ensuring that royalty owners, including the Federal government and various Indian Tribes, would be treated fairly as produced natural gas changed hands on its way from the wellhead to gatherers, processors and/or end users. Early drafts of the regulations would have caused thousands of leases to be abandoned, since they would have essentially eliminated allocation measurement and required custody transfer quality measurement at every producing location, no matter what the economic impact might be. Literally, tens of thousands of marginal leases would have become uneconomical.
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Document ID: 33B597AC

Introduction To Gas Quality
Author(s): Robert Hornberger
Abstract/Introduction:
Gas quality is a vital part of determining the value of the natural gas that is being produced, gathered, transported or consumed. Gas quality measurement is also important for the safety and environmental impact of the pipeline system.
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Document ID: 3CD8D8D0

Use Of Equations Of State Software In Natural Gas Sampling
Author(s): Donald P. Mayeaux
Abstract/Introduction:
Proper sample conditioning is essential to providing a representative sample of natural gas to the analyzer. Sample conditioning consists of extracting a sample from a process stream, transporting it to an analyzer, and conditioning it so that it is compatible with the analyzer. Conditioning generally consists of controlling the gas temperature, pressure, and flow rate. It also includes the removal of contaminates which may alter the sample composition and/or damage the analyzer. It is imperative that the gas sample composition is not altered or distorted during the conditioning process. Equations of State (EOS) software programs are useful tools for modeling the behavior of natural gas as it flows through a sample system. With the use of an EOS program one can determine if conditions in a particular sample conditioning system are conducive to the proper sampling of a specific natural gas composition. EOS software can be useful to the engineer or technician during the design, operation, and maintenance of a natural gas sampling system. This paper will discuss the types of information an EOS program can provide and how this can be utilized to solve common sample conditioning problems.
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Document ID: 2DF3B901

Fugitive Methane Emissions Measurement In The Natural Gas Industry Research( Authored By Touche Howard)
Author(s): Milton W. Heath III
Abstract/Introduction:
The natural gas industry is currently seeking to reduce natural gas loss and methane emissions to the atmosphere. In 1995, extensive measurements of leak rates at natural gas facilities conducted by Indaco and sponsored by the Pipeline Research Committee (PRCI) and the U.S. Environmental Protection Agency (EPA) indicated gas losses due to leak rates from transmission natural gas compressor stations may have averaged 35,000 Mcf/station/year, equivalent to a loss of 70,000/year at 2/Mcf. Using the price of gas today, that figure would be 175,000/year at 5/Mcf.
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Document ID: 8DBFAE46

The Chemistry And Characteristics Of Gas Odorants
Author(s): Thomas E. Tucker
Abstract/Introduction:
Modern industry conducts itself much differently than it did at the turn of the century. Public safety and care for the environment has gone from the bottom of the list of goals, right to the very top. This has come about for a variety of reasons, including increased knowledge of the products, processes and services offered together with the hazards associated with them, greater awareness of the effects on the population and environment, and the introduction of legislation to ensure compliance with the standard practices necessary to ensure these goals are met.
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Document ID: 40F02A32

Managing Noise
Author(s): James L. Robertson, Robert C. Becken
Abstract/Introduction:
Webster defines noise as a sound, especially one that lacks agreeable musical quality or is noticeably unpleasant. In the gas industry, objectionable sounds can come from relief valve discharges, gas blowdowns, compression equipment running, control valves throttling, and normal (and abnormal) pipeline flows. Noise emanating from pipelines can be caused by reasons other than gas flowing. Debris left in a pipeline after construction can cause metallic noises. Noise can also be generated by liquids moving in the gas flow stream. Noise can travel long distances, as was evidenced by a problem a gas transmission company experienced many years ago in Georgia. A woman started hearing a popcorn popping sound in her front yard where a gas transmission line was buried. The transmission company spent months trying to determine the source of the noise without success, until a routine maintenance check of their mainline valves uncovered a vandalized valve which had been partially closed. When this valve (which was located almost ten miles upstream) was opened, the noise disappeared in the ladys front yard. This paper will primarily focus on noise coming from the throttling of gas in regulating stations. Control valve generated noise, resulting from gas pressure reduction (regulation), can exceed OSHA or local noise limits or can cause destructive damage to regulating equipment and pipe components. Too often, potential regulation generated noise is an afterthought of station design. Its importance is realized only after noise complaints or noise generated damage to regulating equipment is brought forcefully to the designers attention. Including a look at regulation noise as an integral part of station design can avoid excessive noise problems and expensive noise abating post installation modifications. Following are brief descriptions of the causes of regulation noise and the tools available to keep them within acceptable levels.
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Document ID: B6FE2CC4

Industrial Pressure Control A Regulator Station Design For Large Combustion Turbine Engine Power Plants Coupled With Small Auxiliary Loads
Author(s): Jim Green
Abstract/Introduction:
Regulator station designs for pressure control to large industrial loads have always presented unique challenges that differ from standard pipeline pressure control applications. A large industrial load with little buffering between the regulators and burner tips requires a different approach to station design. The design approach becomes even more complicated if the large industrial load also has additional small auxiliary requirements such as duct burners, waste heat recovery boilers, or building heat requirements. In this paper, the focus will be on a regulator station design for the newer Advanced Combined Cycle Combustion Turbine (CT) Power Plants that meet the load requirements for power plant operation as well as the load requirements for ancillary equipment.
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Document ID: 04CCAAF0

Regulator Freeze Protection
Author(s): Michael W. Gillis
Abstract/Introduction:
In the transportation of natural gas from wellhead to consumer, service conditions will be encountered which may cause the gas and equipment used to regulate and control pressure to experience freezing conditions. Ignoring these design considerations will result in reduced facility reliability and increased operating and maintenance costs. Regulator or control valve freeze off at pressure reducing stations, resulting from the cooling effect of pressure reduction, can cause serious operational and safety problems. The freeze off can result in the regulator becoming inoperable causing a potential loss of pressure control or even result in the loss of service to downstream customers.
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Document ID: AE374D94

Flexible Element Regulators
Author(s): John R. Anderson
Abstract/Introduction:
Traditionally in pressure control applications involving a self contained pressure regulator, the restricting element consisted of a metal valve plug with knife edges against an elastomer seat (figure 1).
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Document ID: 068F6AF0

Introduction To Regulator And Relief Sizing
Author(s): Ken Ludvigsen
Abstract/Introduction:
Sizing regulators and relief valves properly in a gas system is a fundamental yet critical step to providing safe, reliable service to customers, and achieving a long service life from the regulation equipment installed. This paper will discuss fundamental sizing and cover some of the different considerations when choosing different types of regulators. Once a base is established for pressure regulating fundamentals, this will be used as a base to discuss relief sizing criteria and application.
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Document ID: 1D04BEED

Introduction To Over Pressure Protection
Author(s): Steve Pastrano
Abstract/Introduction:
As far as we know, the first over pressure protection equipment used for natural gas was a pressure relief device. It consisted of a pressurized pipe faced down into a pool (pot) of liquid (water, oil or mercury). On an over pressure, the gas would displace the liquid seal over the end of the pipe and bubble to the atmosphere. The gas industry has progressed since the use of liquid seal devices. We will discuss the various types of over pressure protection that is currently utilized by gas companies worldwide.
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Document ID: 736BA6BD

Fundamental Principles Of Pressure Regulators
Author(s): Kevin Shaw
Abstract/Introduction:
The following paper will concentrate on the fundamentals and principles of natural gas pressure regulators. In the gas regulators conception it was mainly a device used to reduce high pressure to a more usable lower pressure. Today, more is expected from the performance of the pressure regulator. Pressure reduction is no longer the only function needed. The regulator is considered an integral measurement instrument that must adhere to the stringent codes put forth by the U.S. Federal Department of Transportation and many state Public Utility Commissions.
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Document ID: EC035A29

The Theory And Application Of Optical Flow Meters In The Natural Gas Industry
Author(s): Ivan Melnyk
Abstract/Introduction:
Optical means have been successfully utilized in variety of process control applications, they demonstrated high accuracy and ability to measure physical parameters which were impossible to measure otherwise such as distributed and remote temperature sensing, gas analysis, etc. Optical control devices are used in harsh industrial environments due to inherent immunity of the optical sensors to electromagnetic field and their ability to operate at long distances. Application of optical means to flow measurement in the natural gas industry offers a number of advantages which might establish a new class of meters in the industry, optical gas flow meters (OFM). This paper describes the theory and operation of the OFM, and it provides first experimental data from testing the OFM which are based on laser-two-focus principle.
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Document ID: 7695D860


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