Measurement Library

Natural Gas Sampling Technology Conference Publications (2007)

Natural Gas Sampling Recommendations And Common Deficiencies Impact Of API 14.1 On Industry Sampling Methods
Author(s): Fred Van Orsdol
Abstract/Introduction:
The current scope of API Chapter 14.1 is directly related to commitments made to the Bureau of Land Management (BLM) in the late 1980s. At that time, Ray Thompson with the BLM pointed out to me (as the lead industry spokesperson negotiating with the BLM on allocation measurement and other issues) that the industry had many gaps in its standards. He asked if we would close the gaps or if the BLM should plan on closing them for us. On behalf of the industry, and with full support from several API member companies and their representatives, I committed to Ray that we would close the gaps. Later, as Chairman of the API Committee of Gas Fluids Measurement for several years, I pushed to complete the commitments made to Ray. New standards and scope changes to existing standards resulting from that original commitment included API Chapter 20 (allocation measurement), API Chapter 21.1 (flow computers) and an expanded API Chapter 14.1. The scope of API 14.1 was modified to include spot, composite and continuous sampling systems and to include streams rich enough to be at or near their hydrocarbon dewpoint temperature at operating conditions, as well as streams that were processed and custody transfer pipeline quality. In the past, only gases at temperatures well above their hydrocarbon dewpoint were considered in the standards, but the methods in the standards were still applied to rich streams as well. So often, the most critical sampling is performed just downstream of production separators, so we felt this condition could no longer be ignored in the standards. Gas leaving a separator is exactly at its equilibrium vapor pressure and allowing the gas to cool or impact disturbances will produce liquids. Whenever these liquids form in a sampling system, sampling accuracy will suffer. Methods had to be developed to handle this common condition and produce representative samples.
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Document ID: D6D3D2BF

Use Of Equations Of State To Understand The Effects Of Sample Conditioning
Author(s): David F. Bergman
Abstract/Introduction:
Equations of State are a valuable tool for examination of data and for calculations of phase compositions and the properties of the phases such as density, saturation pressure, and vapor liquid ratios. However they can be easily misused as well. This paper will deal with the complexities of using Equation of States and their correct application to gas conditioning issues.
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Document ID: 820449D4

Writing Standards In A Manner Which Provides Technological Advancement
Author(s): Zaki Husain
Abstract/Introduction:
Typical practice in developing standards by most technical organizations is to address certain working principles of non-proprietary commercially available devices and/or accepted industry practice of usage of certain type of device. This practice of developing standards often imposes negative constraints for the users in the industry. Any proprietary device that may offer improved performance characteristic may not be covered by the standard, when the proprietary design or operating principle does not conform to that defined by the standard hence may refrain user from installing such a device. This constraint also withholds manufacturers from improving performance of a device that would employ a proprietary design or operating principle. This imposed shortcoming of the standard for the industry is recognized and it is proposed that a standard should define what the device should achieve and not how it is achieved. A standard should specify the purpose of the device, output of the device with adequately defined testing protocol for the device, and format of the test data and report that will allow the user to evaluate performance of different commercially available devices and select the device that best suits the application and meets the desired performance requirements of the device.
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Document ID: 5235E23D

Analysis Solutions For Sample Vaporization Of LNG
Author(s): Kenneth O. Thompson
Abstract/Introduction:
The following is a discussion of LNG (Liquefied Natural Gas) vaporization for the purpose of sample analysis by a chromatograph to determine composition and calculate BTU content of the liquid in its Natural Gas state.
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Document ID: 6F4D55EF

Installation Of Sample Conditioning Systems
Author(s): Brad Massey
Abstract/Introduction:
This paper is a complete discussion on the proper installation of sample conditioning and transport systems for the delivery of a representative natural gas sample to an analytical device. Sample point considerations, location, extraction methods, filtering, pressure reduction and delivery and will be covered.
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Document ID: 5A133016

Heat Pipe Application To Gas Sample Lines
Author(s): James Witte
Abstract/Introduction:
Heat pipes have been in use for several years in the aerospace and electronics industries for heat transfer applications. These uses include instrument and microprocessor cooling. This paper presents the results of tests that were conducted to determine if a new heat pipe design would be applicable to natural gas sampling installations as heat tracing of sample tubing. A prototype heat pipe produced by A+ Corporation was tested in an environmental chamber at the El Paso Corporation Laboratories in Hockley, TX. This development is a follow on to their existing integral heat pipe sample probe.
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Document ID: B28AE95C

Natural Gas Sampling Systems, The Good And The Bad: A Field Mans Perspective
Author(s): Mark W. Smyth
Abstract/Introduction:
I use a ball valve with a regulator mounted on the top of my pipeline for my moisture analyzer sample gas and it works for me. Why do I need an expensive probe/regulator in the line or anything else? I pull a tube for moisture vapor off the orifice meter piping going to my chart recorderit never agrees with the pipeline techs portable moisture analyzer. The tube must be rightI can see the stain. I dont trust those electronic meterscant see whats going on! In the winter months I dont understand why the moisture vapor reading on my analyzer is extremely low during the nighttime, and during the day it becomes very highit seems my moisture analyzer is only an expensive clock. During colder weather, the sensor in my oxygen analyzer fails and I must replace it a couple of times. What is wrong? The sensor in my moisture analyzer becomes contaminated in a very short time, and it is necessary for me to recondition the sensor in only one to two weeks. I installed a probe/regulator with a membrane filter in my sample system, but it didnt seem to help. These common statements and the hidden measurement errors due to improper sampling methods will be reviewed in this paper, along with viewpoints on why some field technicians are not following existing standards. Problems with misapplication of membrane separators and vapor absorbents for glycol, amines and compressor lube oil will also be discussed in this paper along with suggestions for proper application of these devices.
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Document ID: 32B83497

Modular Sample Conditioning Systems
Author(s): Donald P. Mayeaux
Abstract/Introduction:
Prior to 1992, sample conditioning systems consisted of components mounted to a back plane and interconnected with pipe and tubing. This type of construction required a large amount of space. The interconnecting tube and piping had a large internal volume and were difficult to purge. To make matters worse, the components, for the most part, were originally designed for pneumatic and hydraulic service and modified for sample conditioning. One might say that the system were not analytically correct. Analyzer designs improved rapidly but the sample system designs were slow to change. Although sample systems have improved substantially, they still are the weak link in on line analytical systems. This presentation will discuss the history of a significant improvement in sample conditioning, the modular approach to building sample systems. Also discussed will be its benefits and designs which are specific for the Natural Gas industry.
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Document ID: CFC3ABC7

Natural Gas Sampling Recommendations And Common Deficiencies Impact Of API 14.1 On Industry Sampling Methods
Author(s): Fred Van Orsdol
Abstract/Introduction:
The current scope of API Chapter 14.1 is directly related to commitments made to the Bureau of Land Management (BLM) in the late 1980s. At that time, Ray Thompson with the BLM pointed out to me (as the lead industry spokesperson negotiating with the BLM on allocation measurement and other issues) that the industry had many gaps in its standards. He asked if we would close the gaps or if the BLM should plan on closing them for us. On behalf of the industry, and with full support from several API member companies and their representatives, I committed to Ray that we would close the gaps. Later, as Chairman of the API Committee of Gas Fluids Measurement for several years, I pushed to complete the commitments made to Ray. New standards and scope changes to existing standards resulting from that original commitment included API Chapter 20 (allocation measurement), API Chapter 21.1 (flow computers) and an expanded API Chapter 14.1. The scope of API 14.1 was modified to include spot, composite and continuous sampling systems and to include streams rich enough to be at or near their hydrocarbon dewpoint temperature at operating conditions, as well as streams that were processed and custody transfer pipeline quality. In the past, only gases at temperatures well above their hydrocarbon dewpoint were considered in the standards, but the methods in the standards were still applied to rich streams as well. So often, the most critical sampling is performed just downstream of production separators, so we felt this condition could no longer be ignored in the standards. Gas leaving a separator is exactly at its equilibrium vapor pressure and allowing the gas to cool or impact disturbances will produce liquids. Whenever these liquids form in a sampling system, sampling accuracy will suffer. Methods had to be developed to handle this common condition and produce representative samples.
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Document ID: 75C967F0

Use Of Equations Of State To Understand The Effects Of Sample Conditioning
Author(s): David F. Bergman
Abstract/Introduction:
Equations of State are a valuable tool for examination of data and for calculations of phase compositions and the properties of the phases such as density, saturation pressure, and vapor liquid ratios. However they can be easily misused as well. This paper will deal with the complexities of using Equation of States and their correct application to gas conditioning issues.
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Document ID: 34871C22

Impact Of Gpa 2166 On Industry Sampling Methods
Author(s): Mark Scripsick
Abstract/Introduction:
It has long been understood that the representative sample of the flowing stream is the first and most important step in the accurate analysis of natural gas. The cooperative sampling program carried out for the revision of API 14.1 demonstrated several areas where the GPA sampling method could be refined, revised and improved to better meet industry needs. Essentially, the API 14.1 work documented the challenges and requirements necessary to obtain a representative sample and the revision of GPA 2166 addresses the methods to meet those challenges and requirements. It is suggested that anyone attempting to sample natural gas obtain, read, and understand both documents.
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Document ID: E9F49683

The Physics And Chemistry Of Natural Gas Sampling And Conditioning
Author(s): Darin L. George,
Abstract/Introduction:
Recent research has led to changes in industry standards for natural gas sampling, such as the API Manual of Petroleum Measurement Standards Chapter 14.1 and GPA 2166. To best apply these standards, users should understand the physical phenomena that can lead to inaccurate samples. This presentation will review the physics of natural gas sampling, including phenomena such as adsorption and desorption, vapor-liquid equilibrium, and Joule-Thomson cooling the use of the phase diagram as a sampling tool and results of research on the physics of natural gas sampling that have led to new industry standards.
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Document ID: BA1EB796

Approach To Designing A Natural Gas Sampling System
Author(s): Don Sextro
Abstract/Introduction:
Many properties of a natural gas stream are important to measuring its quantity and quality, as well as to successfully operating pipelines and plants. These include composition which is used to calculate heating value, density and hydrocarbon dew point concentration of contaminants and water vapor dew point. Results from these measurements are directly used to determine the value of the stream and may affect decisions regarding the acceptability of the stream with respect to specification limits. These measurements are made on a sample extracted from the flowing stream that must accurately represent the characteristics of the flowing gas. It is the process of capturing and transporting this sample that is vulnerable to distortion. Sample distortion is not uncommon and when it exists causes subsequent measurements to not be representative of the flowing stream which then affects quantity and quality determinations and operational decisions. As such, sound sampling system design is important to both measurement and operation.
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Document ID: 321EB68A

Modular Sample Conditioning Systems
Author(s): Donald P. Mayeaux
Abstract/Introduction:
Prior to 1992, sample conditioning systems consisted of components mounted to a back plane and interconnected with pipe and tubing. This type of construction required a large amount of space. The interconnecting tube and piping had a large internal volume and were difficult to purge. To make matters worse, the components, for the most part, were originally designed for pneumatic and hydraulic service and modified for sample conditioning. One might say that the system were not analytically correct. Analyzer designs improved rapidly but the sample system designs were slow to change. Although sample systems have improved substantially, they still are the weak link in on line analytical systems. This presentation will discuss the history of a significant improvement in sample conditioning, the modular approach to building sample systems. Also discussed will be its benefits and designs which are specific for the Natural Gas industry.
Go to Download Page
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Document ID: 8902D5F6

Natural Gas Sampling Systems, The Good And The Bad: A Field Mans Perspective
Author(s): Mark W. Smyth
Abstract/Introduction:
I use a ball valve with a regulator mounted on the top of my pipeline for my moisture analyzer sample gas and it works for me. Why do I need an expensive probe/regulator in the line or anything else? I pull a tube for moisture vapor off the orifice meter piping going to my chart recorderit never agrees with the pipeline techs portable moisture analyzer. The tube must be rightI can see the stain. I dont trust those electronic meterscant see whats going on! In the winter months I dont understand why the moisture vapor reading on my analyzer is extremely low during the nighttime, and during the day it becomes very highit seems my moisture analyzer is only an expensive clock. During colder weather, the sensor in my oxygen analyzer fails and I must replace it a couple of times. What is wrong? The sensor in my moisture analyzer becomes contaminated in a very short time, and it is necessary for me to recondition the sensor in only one to two weeks. I installed a probe/regulator with a membrane filter in my sample system, but it didnt seem to help. These common statements and the hidden measurement errors due to improper sampling methods will be reviewed in this paper, along with viewpoints on why some field technicians are not following existing standards. Problems with misapplication of membrane separators and vapor absorbents for glycol, amines and compressor lube oil will also be discussed in this paper along with suggestions for proper application of these devices.
Go to Download Page
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Document ID: 856B8CB7

Heat Pipe Application To Gas Sample Lines
Author(s): James Witte
Abstract/Introduction:
Heat pipes have been in use for several years in the aerospace and electronics industries for heat transfer applications. These uses include instrument and microprocessor cooling. This paper presents the results of tests that were conducted to determine if a new heat pipe design would be applicable to natural gas sampling installations as heat tracing of sample tubing. A prototype heat pipe produced by A+ Corporation was tested in an environmental chamber at the El Paso Corporation Laboratories in Hockley, TX. This development is a follow on to their existing integral heat pipe sample probe.
Go to Download Page
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Document ID: C889EC78

Analysis Solutions For Sample Vaporization Of LNG
Author(s): Kenneth O. Thompson Jr.
Abstract/Introduction:
The following is a discussion of LNG (Liquefied Natural Gas) vaporization for the purpose of sample analysis by a chromatograph to determine composition and calculate BTU content of the liquid in its Natural Gas state.
Go to Download Page
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Document ID: 717250A1

Installation Of Sample Conditioning Systems
Author(s): Brad Massey
Abstract/Introduction:
This paper is a complete discussion on the proper installation of sample conditioning and transport systems for the delivery of a representative natural gas sample to an analytical device. Sample point considerations, location, extraction methods, filtering, pressure reduction and delivery and will be covered.
Go to Download Page
Email Reference
Document ID: 882A89EE

The Importance Of Training Natural Gas Technicians
Author(s): Mark Firmin
Abstract/Introduction:
The custody meter is the cash register. Thats a common saying in the natural gas industry that does a great job of emphasizing the direct financial impact of measurement. The equipment and methods used for measurement are implemented by measurement personnel, and training affects the abilities of people. It follows then, that training of measurement personnel has a financial impact on natural gas companies. Lack of good training could be costing natural gas companies a great deal of money. What is being bought and sold at the custody meter is energy. The assessment of the amount of that energy is influenced by many factors that all fall into two categories: accurate flow measurement and accurate analysis of the gas. Even if the flow measuring equipment and the analyzer are working perfectly, if the sample provided to the analyzer does not represent the gas flowing through the meter, then the heating value calculated from the composition will not be correct and the amount money that changes hands will not be correct. The industry universally acknowledges, and widely accepts, that sample handling and conditioning is overwhelmingly the largest source of errors in gas analysis, yet the focus has been on the analyzer rather than the sample system, especially when it comes to training. The focus of this paper is on the impact that training can have in the area of sample handling and conditioning.
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Document ID: 49448CA9

Approach To Designing A Natural Gas Sampling System
Author(s): Don Sextro
Abstract/Introduction:
Many properties of a natural gas stream are important to measuring its quantity and quality, as well as to successfully operating pipelines and plants. These include composition which is used to calculate heating value, density and hydrocarbon dew point concentration of contaminants and water vapor dew point. Results from these measurements are directly used to determine the value of the stream and may affect decisions regarding the acceptability of the stream with respect to specification limits. These measurements are made on a sample extracted from the flowing stream that must accurately represent the characteristics of the flowing gas. It is the process of capturing and transporting this sample that is vulnerable to distortion. Sample distortion is not uncommon and when it exists causes subsequent measurements to not be representative of the flowing stream which then affects quantity and quality determinations and operational decisions. As such, sound sampling system design is important to both measurement and operation.
Go to Download Page
Email Reference
Document ID: DE313745

Writing Standards In A Manner Which Provides Technological Advancement
Author(s): Zaki Husain
Abstract/Introduction:
Typical practice in developing standards by most technical organizations is to address certain working principles of non-proprietary commercially available devices and/or accepted industry practice of usage of certain type of device. This practice of developing standards often imposes negative constraints for the users in the industry. Any proprietary device that may offer improved performance characteristic may not be covered by the standard, when the proprietary design or operating principle does not conform to that defined by the standard hence may refrain user from installing such a device. This constraint also withholds manufacturers from improving performance of a device that would employ a proprietary design or operating principle. This imposed shortcoming of the standard for the industry is recognized and it is proposed that a standard should define what the device should achieve and not how it is achieved. A standard should specify the purpose of the device, output of the device with adequately defined testing protocol for the device, and format of the test data and report that will allow the user to evaluate performance of different commercially available devices and select the device that best suits the application and meets the desired performance requirements of the device.
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Document ID: FF5A659E

Transporting Natural Gas Samples From The Pipeline To A Gas Chromatograph At Low Ambient Temperature Conditions Without Heating
Author(s): Robert Rayburn
Abstract/Introduction:
This paper is a collaboration between Texas Gas Transmission and A Plus Corporation. Texas Gas has long been interested in the work of Donald Mayeaux, C.E.O of A Plus Corporation. Texas Gas has several facilities near A Pluss manufacturing, Texas Gas has made these facilities available to A+ for testing and developing new products. This 20 year relationship has been a benefit for both parties. A special note of thanks is due Don and all the staff at A Plus for their dedication to improving sampling systems.
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Document ID: 0EFE75DE

Impact Of Gpa 2166 On Industry Sampling Methods
Author(s): Mark Scripsick
Abstract/Introduction:
It has long been understood that the representative sample of the flowing stream is the first and most important step in the accurate analysis of natural gas. The cooperative sampling program carried out for the revision of API 14.1 demonstrated several areas where the GPA sampling method could be refined, revised and improved to better meet industry needs. Essentially, the API 14.1 work documented the challenges and requirements necessary to obtain a representative sample and the revision of GPA 2166 addresses the methods to meet those challenges and requirements. It is suggested that anyone attempting to sample natural gas obtain, read, and understand both documents.
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Document ID: 773F562B

Research Results Of Cylinder Temperature Changes Which Occur During Spot Sampling
Author(s): Donald P. Mayeaux, Jay St. Amant
Abstract/Introduction:
Spot and composite sampling with cylinders play an important role in determining the monetary value of Natural Gas. This form of sampling is often utilized when it is not economically feasible to install a permanent on-line analyzer. The API 14.1 and GPA 2166 working groups have focused much attention on the development of methods for spot and composite sampling. The consensus is that natural gas which is well above its Hydrocarbon Dew Point Temperature (HCDPT) is relatively easy to sample with cylinders. It is also the consensus that when the gas being sampled is at or near its HCDPT, obtaining a representative sample is difficult. This is especially true when sampling at low ambient temperatures. A contributing factor is that only recently has a representative sample been defined as the vapor phase of the gas at the pressure and temperature of the source.
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Document ID: 94B2692F

Research Results Of Cylinder Temperature Changes Which Occur During Spot Sampling
Author(s): Donald P. Mayeaux, Jay St. Amant
Abstract/Introduction:
Spot and composite sampling with cylinders play an important role in determining the monetary value of Natural Gas. This form of sampling is often utilized when it is not economically feasible to install a permanent on-line analyzer. The API 14.1 and GPA 2166 working groups have focused much attention on the development of methods for spot and composite sampling. The consensus is that natural gas which is well above its Hydrocarbon Dew Point Temperature (HCDPT) is relatively easy to sample with cylinders. It is also the consensus that when the gas being sampled is at or near its HCDPT, obtaining a representative sample is difficult. This is especially true when sampling at low ambient temperatures. A contributing factor is that only recently has a representative sample been defined as the vapor phase of the gas at the pressure and temperature of the source.
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Document ID: C4DC88FA

Transporting Natural Gas Samples From The Pipeline To A Gas Chromatograph At Low Ambient Temperature Conditions Without Heating
Author(s): Robert Rayburn
Abstract/Introduction:
This paper is a collaboration between Texas Gas Transmission and A Plus Corporation. Texas Gas has long been interested in the work of Donald Mayeaux, C.E.O of A Plus Corporation. Texas Gas has several facilities near A Pluss manufacturing, Texas Gas has made these facilities available to A+ for testing and developing new products. This 20 year relationship has been a benefit for both parties. A special note of thanks is due Don and all the staff at A Plus for their dedication to improving sampling systems.
Go to Download Page
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Document ID: 9A2BE1F7

The Physics And Chemistry Of Natural Gas Sampling And Conditioning
Author(s): Darin L. George
Abstract/Introduction:
Recent research has led to changes in industry standards for natural gas sampling, such as the API Manual of Petroleum Measurement Standards Chapter 14.1 and GPA 2166. To best apply these standards, users should understand the physical phenomena that can lead to inaccurate samples. This presentation will review the physics of natural gas sampling, including phenomena such as adsorption and desorption, vapor-liquid equilibrium, and Joule-Thomson cooling the use of the phase diagram as a sampling tool and results of research on the physics of natural gas sampling that have led to new industry standards.
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Document ID: 2A12BD1B

Method For Performance Testing Of Natural Gas Sampling Systems
Author(s): Donald P. Mayeaux
Abstract/Introduction:
The analysis of natural gas (NG) plays a key role in determining its monetary value. The NG BTU content value and the physical properties utilized in computing its volume, both of which directly impact its value, are derived from compositional analysis. The typical on line natural gas analytical system is divided into two basic sections. The analyzer, which is typically a gas chromatograph (GC) and a sample conditioning system (SCS).The function of the SCS is to extract a representative sample from the source gas, usually a pipeline, condition it, then transport it to the analyzer for compositional analysis. It is a well accepted fact that the SCS is the source of more than 75% of the errors involved in the analysis of NG. Given this fact, it is baffling that the analyzer, which contributes the least error, has been the focus of attention. Industry standards, such as the API chapter 14, section 1, provide valuable guidelines for the design, construction and operation of the SCS. The standards also provide guidance on the preparation, transportation, and storage of the gas mixture utilized in calibrating the online GCs. However, to the authors knowledge, there are currently no standardized methods of testing or verifying the performance of sampling conditioning systems for on line GC analysis of NG.
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Document ID: B141569A

A Method For Performance Testing Of Natural Gas Sampling Systems
Author(s): Donald P. Mayeaux
Abstract/Introduction:
The analysis of natural gas (NG) plays a key role in determining its monetary value. The NG BTU content value and the physical properties utilized in computing its volume, both of which directly impact its value, are derived from compositional analysis. The typical on line natural gas analytical system is divided into two basic sections. The analyzer, which is typically a gas chromatograph (GC) and a sample conditioning system (SCS).The function of the SCS is to extract a representative sample from the source gas, usually a pipeline, condition it, then transport it to the analyzer for compositional analysis. It is a well accepted fact that the SCS is the source of more than 75% of the errors involved in the analysis of NG. Given this fact, it is baffling that the analyzer, which contributes the least error, has been the focus of attention. Industry standards, such as the API chapter 14, section 1, provide valuable guidelines for the design, construction and operation of the SCS. The standards also provide guidance on the preparation, transportation, and storage of the gas mixture utilized in calibrating the online GCs. However, to the authors knowledge, there are currently no standardized methods of testing or verifying the performance of sampling conditioning systems for on line GC analysis of NG.
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Document ID: D1B3990A


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