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Analyser Sample Systems
Analyser Sample Systems require experienced design engineering in order to achieve a representative, conditioned sample for analysis. Engineering design requires careful selection of materials, temperature and pressure conditioning along with correct process data. Don't forget, it is generally accepted that analyser sample systems are the victims of the Pareto principle (i.e., 20% of a system consumes 80% of the resources) since they are responsible for 80% of analyser system problems. This Analyser Sample Systems page and our sponsor Haldatec hopefully will assist in getting this very important design and component selection correct.

Haldatec  

Since 1990 Haldatec have been providing  innovative products, systems and services to the Oil, Gas and related industries in Australia, Pakistan, Singapore, Papua Nugini, India, Malaysia, Italy, Thailand and New Zealand. Their main focus initially was in Oil and Gas Sampling, since then there has been a broader involvement into areas such as Gas Control Valves, Gas Tank Blanketing, Instrument gas skids,  Pipeline Insertion Devices, gas filtration, instrument manifolds, leak detection and Odorant Injection systems. The Haldatec product line includes;

Have a question on or need to purchase quality Sample Systems or their Components? Our Sponsors Haldatec are Experts in this area!
Contact them here. 

Go to Specific Subject: Analyser Sampling System Technical Resources | Samplers | Analyser Sample Systems - The Basics | Analyser Sample Systems Design | Sampling System Standards | Sampling System Applications | Forums and Organisations | NeSSI Modular Sampling System | Sampling Cylinders


Analyser Sampling System Technical Resources from our Sponsor Haldatec

Practical Considerations of Gas Sampling, Gas Sampling Systems and Standards - David J Fish - The need to be able to take a representative sample of a hydrocarbon product is necessary to ensure proper accounting for transactions and efficient product processing. The various sampling methods that are available and the options and limitations of these methods are investigated; the most appropriate equipment to use; the reasons for its use and correct installation of the equipment are also addressed.
Spot and Composite Sampling for BTU Analysis - Determination and Natural Gas Physical Properties - David J. Fish - The amount of hydrocarbon product that is transported between producer, processor, distributor and user is significant. To be able to verify the exact composition of the product is important from an economic and product treatment standpoint. A small percentage savings made by correctly determining composition will quickly recoup the investment made in the purchase of a system designed to obtain an optimum sample. In addition, if the best sampling procedures are followed, the potential for disputes between supplier and customer will be greatly reduced. The importance of properly determining hydrocarbon gas composition benefits all parties involved and will achieve greater significance as this resource becomes more expensive and plays a larger role in our energy needs worldwide.
Eliminating Guesswork – Predicting Gas Temperatures for Analysers - Industry now has available prediction techniques for calculating the temperature of pipeline gas that is being presented to on-line analysers. Thus the risk has been taken out of having a liquid laden sample or a non representative sample, that can damage analysers or not make the analysis meaningful. Proprietary programmes have been developed specifically for use with Welker insertion regulators and Pressure Tech heated regulators.
Instrument Filters - These filters are used extensively for removing contaminates that include dust, aerosols and water from the gas before it is used for such duties as gas supply to pneumatic instruments, valve actuators, and analysers.
Pressure Regulators for Analyser Applications - Pressure regulators are self contained devices that are often defined by their application. Hence similar regulators are described as Instrument or Analyser or High/Low Pressure.
Whether the regulator is a liquid or gas regulator they all work in the same way. Porting may be different. Sizing is of course different with flow being constrained by the physical size of the regulator and it's flow configuration.
Self Contained Pressure Regulator - Sizing - This technical paper gives a technical introduction on self contained pressure regulators, capacity sizing, turndown and relief sizing.
Typical Crude Oil Sampling System - This technical diagram shows a typical crude oil sampling system. 
Analyzer Liquid Shutoff and Eliminator Membrane Filter - The Liquid Eliminator is designed to protect analyzers from damage and contamination by removing liquids and particulates in gas samples. The gas sample enters the housing and flows through the membrane, effectively eliminating any free liquids from entering the analyzer columns.
Flow Conditioner - This flow conditioner is designed to protect analytical instruments from liquids. Welker has taken two of it’s products and combined them into one great product. The “Guardian” is quick and easy to install. The “Guardian” is equipped with a shut-off ball that floats on the free liquid and moves up to shut off the flow of liquid slugs that would flood the analyzer. This design is to help protect analyzers from damage and contamination by removing liquids and particulates while sampling.

Sampling System Applications

Hot Loop Sample Probe Conditioning System specially designed for Moisture Analysers on Triethylene Glycol Dehydration Units - This unit  is designed to gather a representative sample to remove free liquids and deliver a low pressure gas sample to a analyser.


Samplers

The following are from our sponsor Haldatec
Light Liquid Hydrocarbon Sampling - In the sampling of light liquid hydrocarbons, the liquid state of the sample must be maintained at all times. To accomplish this, the equipment and operating features detailed in this technical list should be employed.
Gas Sampling Applications- Gas Sampling usually takes three forms, spot, continuous or representative, this technical bulletin gives information on this.
Liquid Sampling Applications - Sampling liquids usually takes two forms, spot or representative.
Spot samples are taken at one time at one point, normally via a pitot tube inserted in the process or pipeline. The sample is collected in a sample cylinder and taken to a laboratory for analysis. This form of sampling will only give a sample that is representative at one point in time only. Alternatively, Representative samples of light oil or condensate are collected using a by-pass sampler mounted adjacent to the pipe or mounted directly on the pipe. Grab samples are then collected in a sample cylinder over a period, for later analysis in a laboratory. For heavier oils such as Crude Oil or oils with contaminates in them, the by-pass method is not favoured, a direct mounted insertion type sampler is used. This type of sampler will take a representative sample from the centre of the pipe. The oil should first be thoroughly mixed using an upstream static mixer to ensure the best homogeneous sample is taken.
Collection and Safe Transportation of Hydrocarbon Samples - David A Dobbs and David J Fish - This paper discusses the various types of collection methods and collection devices as well as the importance of proper collection  cylinder construction, benefits of constant pressure sampling together with comparison of results from various sampling methods.  Transporting samples for analysis remote from the collection point is often necessary and presents problems in selecting the appropriate container and mode of transport. Safe transportation is critical and subject to regulation, as well the integrity of the sample needs to be maintained. The various regulations and transport options are also detailed.


Analyser Sample Systems - The Basics

The Basics of Analyzer Sample Systems
Written by Ian Verhappen
Included in this article are two spreadsheets for calculating pressure drops:
Pressure drops in a liquid line
Pressure drops in a vapour line


Analyser Sample Systems Design

Process Analyser Sample Conditioning System Technology Book
This book  provides both novice and experienced technologist with the technical background necessary to choose sample conditioning system components that will allow the process analyzer system to function reliably with minimal maintenance.
The conditioned process sample presented to the process analyzer should be of similar quality to the calibration material used to zero and span the analyzer. Filling a long-standing void in the process field, this book addresses the system concept of Process Analyzer Sample-Conditioning Technology in light of the critical importance of delivering a representative sample of the process stream to the process analyzer. Offering detailed descriptions of the equipment necessary to prepare process samples, and listings of two or more vendors (when available) for equipment reviewed, Process Analyzer Sample-Conditioning System Technology discusses:

• The importance of a "truly representative sample"
• Sample probes, transfer lines, coolers, and pumps
• Sample transfer flow calculations for sizing of lines and system components
• Particulate filters, gas-liquid and liquid-liquid separation devices
• Sample pressure measurement and control
• Enclosures and walk-in shelters, their electrical hazard ratings and climate control systems

How to Manage Vaporization in an Analytical System  - D Nordstrom  and T Waters - When done properly, this process ensures that all compounds vaporize at the same time, preserving the sample’s composition - from Swagelok and Hydrocarbon Processing.
Verify Fluid Flow to Your Analyzer and Keep Your Plant Running - Sam Kresch - No matter how sophisticated a fluid analyzer system may be, it will be ineffective if a sample flow fails to reach the analyzer sensor or if the sample is contaminated or stale. The most advanced systems in the world cannot provide accurate results without a valid fluid sample. Gas chromatographs (GCs), mass spectrometers, optical spectrometers and photometers are a few examples of analyzer technologies applied in process and plant systems that need sample flow assurance. It is an accepted industry best practice that sampling systems have some type of flow monitor to assure valid samples and analysis - from Fluid Components.
How to use a Regulator to Reduce Time Delay in an Analytical System - Doug Nordstrom and Mike Adkins - Process measurements are instantaneous but analyser responses never are. From the tap to the analyser, there is always a time delay. Unfortunately, this delay is often underestimated or misunderstood - from www.chemicalprocessing.com.
Designing On-line Chromatograph systems for Liquid Fractionation Facilities - Murray Fraser - Liquid fractionation plants can optimize their operations by installing on-line gas chromatograph systems that have been properly designed to provide reliable, fast, accurate results. One of the most important, but overlooked, facets of designing an on-line analytical system for gas processing facilities is the sample conditioning system (SCS). The sample delivered to the Gas Chromatograph (GC) must truly represent the process media if the measurement is to be accurate — or even meaningful. Samples may be transported to the GC in either gas or liquid phase, but they will ultimately be analysed in the gas phase only. Selection of sample location and careful attention to sample phase (liquid or gas ) is required to ensure optimum system performance. Discussed in this paper are: typical process conditions, GC location, sample transport systems, and details of both vapour- and liquid-phase sample conditioning - from Daniel Measurement and Control.
Breathe Easy - Darrell Leetham -For many organisations today, one aspect of the manufacturing process that needs to be monitored and controlled, for both efficiency and environmental benefit, is gaseous emissions - Plants are constantly looking for means to increase production and decrease costs. Increases in production are generally associated with an increase in fuel consumed and, in turn, a subsequent increase in emissions generated. In addition, regulatory entities are increasingly implementing standards and setting requirements for monitoring and reporting data on plant emissions. In order to improve efficiency throughout a manufacturing process and at the same time meet the needs of sustainable development goals, industry is finding an increased need for robust, reliable and accurate gas analysis methods. To meet the needs of this demand, different technologies for gaseous emissions sampling and analysis have been developed over the years. One particular technique is to extract a gas sample and dilute that sample prior to analysis. This article explains some advantages of the dilution extractive method. From Thermo Fisher Scientific and processonline.com.au. 
The Integrity And Reliability Of On Line Process Analyzers is Crucially Related To The Design Of The Supporting Sample Handling System - Ronald A. Downie - Although a considerable amount of attention is normally given to the selection of the most suitable type of analyzer to perform the desired analytical task, a similar amount of attention is all too often not extended to the sample conditioning system. This may be due to a lack of understanding of the importance of this part of the complete system. A well-designed, properly applied measuring system can do no better than give a correct analysis of the sample being supplied to it. If the sample is not representative of the process, there is nothing an analyzer can do to correct the situation, and the analytical data can not be used for control purposes. The results of poorly designed sample conditioning vary from the analyzer not operating at all to an analyzer operating only with extremely high maintenance requirements and/or giving erroneous or poor data - from Teledyne Analytical Instruments.
Techniques of Composite Sampling - Kris Kimmel - Since a gas sampling system can be referred to as a “cash register” it is very important that the correct sampling method be selected and the appropriate industry standard be followed. Methods reviewed by this paper will include spot sampling, composite sampling, and on-line chromatography. In addition, Gas Processors Association (GPA) 2166-86 and American Petroleum Institute (API) 14.1 will be described - from YZ Systems, Inc and intellisitesuite.com
Sampler Performance Factors - How can you guarantee that a sampling system performs as specified? The performance of a sampling system is normally monitored by measuring the accumulated sample volume and comparing it with the expected sample volume. The variance allowed cross the whole batch is +/-10% - from Jiskoot.
Grab Sampling Systems: Maintaining Quality and Safety  - The need for representative samples plays a critical role in ensuring product verification. Yet sampling directly from the process often includes the risks of exposure to the operator as well as contamination and pollution to the environment. The DOPAK® sampling method reduces such risks with its patented design and simple method of operation. Thanks to Dopak
A New Era of Liquid Chromatography: Improving HPLC Throughput with Automation and Real Time Diagnostics - Today's drug discovery labs are charged with moving thousands of samples through HPLC and MS screening processes. If your lab is operating 24x7 to keep up with the throughput demand, every second counts. To achieve high throughput, not only must the run time of a single analysis be shortened, but the total cycle time of the injection sequence and run time needs to be optimized. Solvent management automation and real time diagnostics allow you to increase sample throughput and maximize system uptime while meeting the need to produce reliable results and identify leads. This automation and diagnostics can be achieved by installing an in-line real time flow measurement device in the solvent management system - from Brooks Instrument.
10.13 A whole swag of Useful Sampling and Conditioning Papers from the NGS Tech 2011 Conference. All the papers are on a single pdf, just scroll down using the index- Paper subjects are;
- The Chemistry and Physics of Natural Gas Sampling and Conditioning - Dr. Darin George
- The Standards Pertaining to Sampling and Conditioning of Natural Gas - Fred Van Orsdol
- Spot and Composite Sampling for BTU Analysis Determination and Natural Gas  Physical Properties - David Fish
- Sample System Design Considerations for “Online” BTU Analysis - Matthew Kinsey Modular Sample Conditioning Systems for Natural Gas Analysis - Jay St. Amant
- Measurement of Water Vapor in Natural Gas by Automated and Manual Water Dew Point Measurement Methods - Dan Potter
- Sampling and Conditioning Natural Gas for H2S and CO2 Analysis - Sam Miller
- Sampling Wet Natural Gas for BTU and Moisture Analysis - Shannon Bromley
- Sampling and Conditioning During Loading, Unloading, and Storage of LNG - Jim Witte
- Benefits of Training Measurement Technicians in the Science of Sample Conditioning and Analysis - Brad Massey
- Are company sampling procedures in line with current standards? - Matt Holmes
5.14 Sampling and Conditioning Papers from the NGS Tech 2014 Conference - All the papers are on a single pdf, just scroll down using the index- Paper subjects are;
- Basic Chemistry and Physics for Sample Conditioning - Jim Witte
- Economics of Compositional and Quality Determination - David Wofford
- Basics for New Engineer/Project Manager - Brad Massey
- API Wet Gas AdHoc Committee Update - David Fish
- New Techniques for Liquid Calibration Standards - Dan Bartel
- Lessons Learned from Sampling in Eagle Ford - Royce Miller
- Wet Gas Sampling - Jay St Amant
- Training New Employees and the Importance/Impact of Baby Boomer Retirement - Gary Hines
- Compressed Natural Gas (CNG) Sampling - Darin George
- New Techniques in LNG Sampling - Ken Thompson
- Improving the Speed and accuracy of Water Vapour and H2S Measurements by Optimising the Sample Transport System - Phil Harris
- Natural Gas Liquid (NGL) Sampling - Eric Estrada
- Injection of Chemicals and the Impact on Sampling - Brad Massey  

The following technical information is from - from Jiskoot
What are the most important steps to consider when Designing or Specifying a Sampling System? - In a typical sampling application, the volume analysed is between 1 and 300 billionth of the total batch. When the custody transfer and batch quality is determined by such a small sample it is vital that it is representative of the fluids being sampled. The standards defines a number of steps that need following to ensure successful sampling.
Why do the Standards Demand that Pipeline Contents must be Homogenous? - A sample is taken from a single point in the pipeline. Water and oil do not mix and therefore it is vital that the point of sampling is representative of a cross section of the pipeline. This can only be achieved by mixing. Natural mixing can be provided by valves, elbows and natural turbulence generated by the flow.
IP Petroleum Measurement - Mark A. Jiskoot The interest in sampling accurately has led to a plethora of studies and the generation of the standards we now use. Much of the original content was based upon what was then known, bolstered with, one hopes, educated guesses. The testing of systems designed within practical/cost limitations has allowed us to accept or reject certain conceptions and better learn the envelope in which we should operate. This paper outlines some of the problems to be addressed and some of the discoveries made.
Sampling Systems - The Options - What is the accuracy of different sampling systems and which is best for your application? There are two main types of sampling systems, probe based systems and bypass loop sampling systems.
What is a Representative Sample? - How do you know if I have a representative sampler?
Sample Receivers - Which type of sample receivers should you use? Once a representative sample has been extracted from the pipeline, it must remain representative in the sample receiver and when analysed in the laboratory.  The standards recommend the use of either fixed or variable volume depending on the properties of the fluids being sampled.
Jet Mixing - A New Approach to Pipeline Conditioning - M.A. Jiskoot - Accurate sampling from a flowing pipeline requires that the point from which the sample is drawn is representative of the average (quality) of the whole cross section.


Sampling System Standards

The following technical information is from - from Jiskoot
What International Standards Govern Sampling System Selection, Design, Installation and Operation? - There are four major standards that govern 'Sampling liquid hydrocarbons in pipelines'.  They are ISO 3171, IP 6.2, API 8.2 and ASTM D4177.
Sampler Control Systems - What type of control system is recommended by the standards? The primary function of the control system is to operate the sampling device in a time or flow proportional manner. This normally requires that the controller have a real-time operating system.  The system should allow the operator to enter the batch size and should determine the necessary sampling rate to achieve the correct volume of sample.
Sampling System Proving - How can you guarantee, prove and certify that a sampling system complies with the standards? A sampling system needs proving once installed. Only then can you certify that a system performs as specified. The only way to prove beyond doubt that an installed sampling system complies with the standards is to prove the system by water injection.  The procedure is defined in the standards.
Crude Oil Sampling - Crude oil sampling for custody transfer, fiscal, allocation or quality measurement purposes should be performed in accordance with sampling standards of ISO 3171, ASTM D 4177, API 8.2 and IP 6.2.  These standards dictate a number of key design issues and steps that must be considered to ensure a system fully complies with the standards.


Sampling System Applications

The following technical information is from - from Jiskoot
How can you decide which type of Mixing System is Best Suited to your Application?
- Selection of the correct mixer as with any process conditioning depends greatly on the application.  There are two main types of pipeline mixing systems available.

Crude Oil Sampling

The following technical information is from - from Jiskoot
The “Art” of Crude Oil Sampling - Mark Jiskoot - Crude oil is sampled to establish the composition quality, density and water content. The quality is normally known when the oil is purchased, as is the approximate density, for a cargo there is "expected" water content but receipt terminals can often be surprised by a water content that is far higher than the "bill of lading" as stated by the loading port. Depending on how the purchase contracts are written, discovery of more water may give rise to a claim first on the shipper and then on the supplier. 
Crude Oil Sampling Customer Satisfaction - Mark A. Jiskoot - Loss control specialists wish to be sure of both the quantity and quality of the oil received on board ship and at point of discharge (receipt port). Confidence in the measurement accuracy reduces risk and improves the demand price of the batch. The quality measurement accuracy is a function of all the steps involved in sampling, failure to maintain the representive sample at any point i.e. from pipeline to analysis invalidates the sample by introducing random errors.
Crude Oil and Condensate Sampling, Water in Oil and Density Measurement - What is the uncertainty of your quality measurement system? - Mark A. Jiskoot - The various standards applicable to sampling, density and on-line water content measurement have been developed and updated over many years but the most significant advances have happened over the last 20 years. While sampling systems have always been a feature of the metering process, many metering systems installed have been modified to incorporate density compensation (to yield total mass) water-in-oil monitors (OWD or On-line Water in petroleum Devices) or both. Integrated systems are now titled QMS or “Quality Measurement Systems”. Unfortunately, and to their cost (at least that of their company), many loss controllers pay the price for poor measurement by way of claims so there is a strong commercial reason to get measurement “right”.
Crude Oil Quality Measurement -Loss Reduction Through Technology - Jon Moreau & Mark Jiskoot - Quality measurement system design and laboratory equipment, handling techniques and analysis methods have improved significantly over the last 20 years. Simultaneously, suppliers and users have worked together to develop/validate and improve measurement performance. One of the most significant steps in achieving this has been the collation and evaluation of water injection "proving" tests. This large (often independently validated) and rapidly growing data set enables a comparative evaluation of the performance of custody transfer sampling/on-line measurement systems. Proving the accuracy of an installed quality-measurement system is a challenge, even more so than proving a metering system. It requires adjustment of a physical property (in this case water content) and validating that the system accurately measures that change. However, unless an installed system has been proved and certified as compliant with the standards, its use to arbitrate claims or for custody transfer becomes questionable.
Increased Profitability through Effective Measurement - Mark A. Jiskoot & Jon Moreau -  The measurement of a Crude Oil shipment at an import terminal forms the basic measure of profit performance.Accurate techniques for measurement of flow are well documented and understood. The factor that is often overlooked is the accurate measurement of actual water, density and composition. Crude oil and water do not mix and therefore it is fundamental that any measurement of water content not only considers carefully how a sample is extracted but also how it is handled and tested. Typical errors in poor sampling techniques result in payment of oil prices both to transport and to process water. While the percentage errors between sampling methodologies may appear insignificant (of the order of 0.05- 0.15%) the volumes of crude traded make the losses significant and can easily justify the installation of an accurate sampling system that both the seller and purchaser can be confident in. The International standards of ISO 3171 clearly define standards which meet the requirement of accurate sampling of liquid hydrocarbons in pipelines.
How Accurate is your Receiving Metering System? - Mark A. Jiskoot - Errors in terminal receipts due to poor sampling designs and procedures can result in huge losses. When receiving crude shipments via tanker, there is some doubt on the quantity of product unloaded. Many errors can be attributed to discrepancies in sampling and metering results. Oil quality measurement methods are under continual review. How much water are you actually purchasing in the latest receipt? An answer is determined by what methods are used to get product densities and the accuracy of laboratory analysis. Should physical sampling methods be replaced with online devices? These are just a few of the issues that refiners must consider as they try to improve the operation of their terminal metering systems.
How can you Sample the Line-fill between the Sampler and Custody Transfer Point? - The volume left in a pipeline after a batch between the sampling system and the point of custody transfer (maybe a metering system or ship's manifold) can be substantial.  In the event that this is large it may be necessary to sample the line-fill to measure the quality, as in the case of ship unloading operations this is often when the worst part of the cargo is discharged.
Improving Customers Profits through Innovation and Technology - Jon Moreau - With the price of crude oil remaining high, many oil companies and refiners are focusing on how new technology can reduce costly measurement errors. The importance of quality as a part of the overall quantity measurement process is being put in the spotlight by rising hydrocarbon prices. 100,000 barrels of crude oil does not have the same value if it contains 1.5% water as it does if it contains 0.5% and poor 'quality' measurement that masks these figures can have a significant impact on profitability.

Fuel Oil Sampling

Fuel Oil (Bunker) Sampling Break the link between Politics and Quality - Mark A. Jiskoot - The objective of sampling is to determine to the highest degree of accuracy possible, the properties of the fluid sampled.This proves beneficial to all parties as it can, if properly executed, ensure fair transactions. As the value of product increases or, as in the case of fuel oil, the potential for claims increase, it is necessary to assure all parties of the properties of the transaction both at the time of sale and in case of dispute later. In reading bunker related press it also becomes obvious that aside of the issue of a "fair deal" assurance of quality can have significant impact on the prevention of engine failure and the consequent disasters and claims than ensue. PSA and DNV have both made serious attempts to assure certain sampling procedures but it is the belief of the author that these are not yet enough. This paper is to outline the basis on which an accurate sample should be taken, sampling techniques which if used will serve to both improve the overall quality of the trade and to determine unintended quality problems which need resolution -  from Jiskoot.

Natural Gas Sampling

Natural Gas Sampling - An Overview - Robert J. J. Jiskoot - Once a by-product of oil production discarded and flared off, Natural Gas has become an increasingly valuable energy source. The ability to verify the composition of the hydrocarbon gas is critical to the determination of its commercial value, be this in gathering, transportation or loading systems. Accurate and reliable sampling allows both buyer and seller to be confident of a fair transaction. The investment associated with the purchase and installation of a composite gas sampling system, correctly designed to provide a representative sample, will be quickly recouped. This paper attempts to outline the correct procedures and considerations that are necessary to obtain a representative gas sample - from Jiskoot.
Advances in Natural Gas Sampling Technology - Donald Mayeaux - The monetary value of natural gas is based on its energy content and volume. The energy content and physical constants utilized in determining its volume are computed from analysis. Therefore correct assessment of the value of natural gas is dependent to a large extent on overall analytical accuracy. The largest source of analytical error in natural gas is distortion of the composition during sampling. Sampling clean, dry natural gas, which is well above its Hydrocarbon Dew Point (HCDP) temperature is a relatively simple task. However, sampling natural gas that is at, near, or below its HCDP temperature is challenging. For these reasons, much attention is being focused on proper methods for sampling natural gas which have a high HCDP temperature. This presentation will address problems associated with sampling natural gas which is at, near, or below its HCDP temperature. Various approaches for solving these problems will also be discussed - from A+ Corporation and intellisitesuite.com
Spot Sampling of Natural Gas - Jerry Bernos - In 1978 the United States Congress passed the Natural Gas Policy Act. This legislation required that natural gas be priced according to its energy content rather than by volume alone. At the same time, the economics of the natural gas industry caused natural gas prices to soar. These two factors resulted in a vast increase in the demand for accurate analyses of natural gas systems. Since it was not economically feasible to place analytical instruments at each and every location requiring BTU determinations, a corresponding increase occurred in the need to obtain "spot" samples of these systems. This paper is intended to present the problems that arise in "spot" sampling and to introduce the industry accepted methods, which can overcome these problems.
Techniques of Gas Spot Sampling - George L. Bell, Sr - A natural gas sample may collected as a spot, composite, or as a continuous sample connected to a chromatograph. The most important things in taking a sample are where and how the sample is taken - From PGI International and intellisitesuite.com

Wet Gas Sampling

Wet Gas Metering / Sampling - New Method to Determine the Liquid Content of a Wet Gas Stream and Provide a Sample of the Liquid Phase for Compositional Analysis.- Mark A. Jiskoot and Ken Payne - There is currently no other method available that is capable of accurate measurement of the liquid mass of a wet gas stream. Jiskoot has, in conjunction with AMEC, developed a wet gas sampling methodology that can determine the liquid/gas mass ratio as well as providing a compositional sample to allow laboratory determination of the chemical composition of condensates, methanol and water.


Analytical Sampling System Forums and Organisations

Center for Process Analytical Chemistry - CPAC, established at the University of Washington in 1984, is a consortium of Industrial, National Laboratory and Government Agency Sponsors addressing multidisciplinary challenges in Process Analytical Technology (PAT) and Process Control through fundamental and directed academic research. The present CPAC program can be summarized by two main components;
(1) new measurement approaches including the miniaturisation of traditional instrumentation and the development of new sensors and non-traditional instruments.
(2) mechanisms for interaction, collaboration, and communication of center activities, research programs, and information related to process analytical technology (PAT) among sponsors, other universities and academic departments, government agencies, and the general measurement and control community.  CPAC has an established track record in fostering academic/industrial/national laboratory interactions, which aim at bridging the gap between basic research and full-scale process/product development.
5.14 ISA Analysis Division - Membership to the Analysis Division provides you with access to a network of knowledge and opportunity to develop your own expertise and share this with fellow professionals. Whether you are already a member or thinking about membership, ISA provides a wealth of industry knowledge at your fingertips and will ensure you are on the cutting edge of technology and developments. In the Analysis Division, we enable our members to do their jobs better and help their organizations strategically use technology so that they, in turn, make the world a better, just, and equitable place. Membership in the ISA entitles you to one free "Automation & Technology" divisional membership. Simply check off "Analysis Division" when you register for your annual ISA membership. You then have access to the finest collection of process analyzer professionals in the world for the price of belonging to the ISA. Don't miss out on this opportunity to be an Analysis Division Member.


NeSSI Modular Sampling System

CT76 Modular Substrate and Component  System - This bulletin from ICEweb sponsor Circor describes why this is "State of the Art" for modular systems. 
Modular Substrate Sampling System (µMSł™) - from ICEweb sponsor Circor
Rethink Sample System Automation - NeSSI provides new tools to tackle the challenges and improve performance - By Robert N. Dubois, consulting analytical specialist - Thanks to chemicalprocessing.com
NeSSI™ Generation II Specification - A Conceptual and Functional Specification Describing the Use of Miniature, Modular Electrical Components for adaptation to the ANSI/ISA SP76 Substrate in Electrically Hazardous Environments -  This functional and conceptual specification is based on the use of the miniaturized, modular analytical systems designed to the ANSI/ISA SP76.00.02-2002 standard substrate. This 2nd generation specification deals chiefly with integrating electrical components such as sensors and actuators (collectively referred to as transducers) onto the substrate in a manner suitable for use in electrically hazardous areas commonly found in petrochemical, refining and chemical facilities - Thanks to CPAC
NeSSI Keeps Chipping Away - The Plucky Sampling Sensor Initiative and Its Advocates Keep On Encouraging Users to Gain the Many Benefits That Its Standardized Hardware, Communications and Microanalytic Specifications Can Bring to Process Analytical Systems -Launched in 2000 by the Center for Process Analytical Chemistry (www.CPAC.Washington.edu) at the University of Washington, Seattle, NeSSI's Generation I specification for its modular, compact, mechanical substrate and other hardware evolved from the ISA SP 76 standard. Next, CPAC and NeSSI's supporters released its Generation II specification for automation and communications in 2004 and more recently, its Generation III specification for microanalytical devices, which is NeSSI's ultimate goal - from Control Global.

The Following articles are from www.chemicalprocessing.com 
NeSSI’s Success should be a Lock - Mark Rosenzweig - The New Sampling/Sensor Initiative or NeSSI that replaces tubing, fittings and other hardware in a sampling system with miniature modular components makes sense. Enhancements now in the works should assure its success.
Intrinsically Safe NeSSI Nears - An emerging bus standard promises to spur application in hazardous environments - Rick Ales - The New Sampling/Sensor Initiative (NeSSI) has provided the basis for modular miniaturized process sampling systems that offer ease of assembly and flexibility while cutting cost of ownership. Not surprisingly, plant acceptance of such NeSSI systems is growing. A group of analyzer specialists now is working to enable NeSSI to be used in hazardous environments. They envision an analytical system with smart transducers that would be capable of being field mounted at the sample point in a potentially explosive atmosphere and would be easily integrated into the analyzer control system.
Smaller, Smarter Systems Streamline Sampling - Mike Spear - An emerging miniaturized, modular approach for sampling systems provides substantial savings in both capital and operating costs - Faced with ever increasing competition on price for their products, chemical companies are constantly searching for ways to cut costs across their operations. This, in turn, puts persistent pressure on engineers to reduce both capital and operating expenditures — without compromising their plants’ reliability and performance in any way. Easier said than done, perhaps, but this is precisely what a new approach to the task of delivering process samples to analyzers actually delivers, claim its proponents. Since coming into being some five years ago, the New Sampling/Sensor Initiative (NeSSI) has become the driving force behind the move to modularize and miniaturize process sampling systems. Now operating under the sponsorship and umbrella of the Center for Process Analytical Chemistry (CPAC) at the University of Washington, Seattle, NeSSI first surfaced as an ad hoc group of people drawn both from equipment manufacturers, keen to adopt the modular approach, and operating companies prepared to put the vendors’ prototype products to the test on their plants.
Streamline Your Sampling System
- Selecting the right stream selection assembly can improve performance
- John Wawrowski, Doug Nordstrom and Joel Feldman.


Sampling Cylinders

Constant Pressure Sample Cylinders with Additional Special Purpose Standard Cylinders - Constant Pressure Cylinders are being increasingly used to address the problem of fugitive emissions in spot sampling situations and have been used for many years in continuous sampling applications. They have minimal dead space, eliminating or minimising the need to purge, are safe to transport, easily cleaned and maintained. There are a variety of construction options and accessories available from our sponsor Haldatec.


Other Useful Information on Sampling Systems 

Sampling Technical Papers - Some super technical information on sampling from Jiskoot International.


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