Sample System 101 in Natural Gas: Enhancing Analytical Precision and Reliability

Sample System Tubing

Understanding the Significance of a Sample Conditioning System

In the intricate landscape of gas analysis, the role of sample conditioning systems stands paramount. These systems, often called sample conditioning systems, play an instrumental role in ensuring that samples extracted from various processes are suitable for analysis by analyzer systems. The journey from source to analyzer involves traversing a multitude of variables, and the sample conditioning system acts as a guardian, maintaining the integrity of the representative sample.

Why Sample Conditioning Matters

The significance of sampling systems cannot be overstated in the intricate realm of process analysis. These systems are the vital link between the raw samples extracted from various processes and the process analyzer systems. By conditioning samples to meet the requirements of analyzers, these systems play a pivotal role in ensuring accurate and meaningful results. Let’s delve into the diverse needs across different sectors and the crucial categories of gas sampling that underscore the importance of sample conditioning.

Four Crucial Categories of Gas Sampling

Fiscal Measurement

In fiscal measurement, the accurate quantification of gases holds immense monetary importance. Sample conditioning systems step in to guarantee the integrity of samples during the journey from source to analysis. This category encompasses processes such as city gate transfer and taxation, where precise measurements are essential for equitable transactions.

Custody Transfer and Taxation

Cherokee Integrations and Solutions Custody Transfer Enclosure Operation

Custody transfer involves the transfer of products between parties, necessitating reliable and accurate sample analysis. In these applications, custody transfer integrations or a custody transfer analyzer enclosure is present. Taxation further accentuates the need for rigor in gas analysis. Sample conditioning systems ensure that samples maintain their representative nature, irrespective of the transfer process, thus fostering fairness and accountability.

Compliance with Contract

In scenarios where products need to adhere to contractual specifications, sample conditioning becomes a paramount concern. These systems facilitate the fulfillment of contractual obligations by ensuring that the samples faithfully represent the characteristics of the gas, providing a solid foundation for informed decisions.

Safety and Downstream Requirements

Safety concerns are paramount in gas analysis, especially when specific components pose potential risks. Sample conditioning systems are pivotal in minimizing such risks by accurately conditioning samples for downstream analysis. Whether it’s about ensuring safety by measuring H2S or monitoring moisture levels, these systems are crucial for maintaining process safety. Safety concerns are paramount in gas analysis, especially when specific components pose potential risks. Sample conditioning systems are pivotal in minimizing such risks by accurately conditioning samples for downstream analysis. Whether it’s about ensuring safety by measuring H2S or monitoring moisture levels, these systems are crucial for maintaining process safety.

Complicating Factors in Sampling

Sampling in the context of gas analysis is not without its complexities, often driven by intricate phenomena that can significantly impact the accuracy and integrity of the sampled gas. Two such factors, the Joule-Thomson Effect, and the Hydrocarbon Dew Point, wield a notable influence on sample composition and analysis.

Joule-Thomson Effect

The Joule-Thomson Effect, a thermodynamic phenomenon, comes into play when a gas expands adiabatically from a region of high pressure to a lower pressure region without a net exchange of energy. This expansion results in a decrease in the gas’s temperature. The consequences of this effect ripple through the sampling system, particularly when dealing with gases transported across various pressure gradients.

The cooling effect induced by the Joule-Thomson Effect can have pronounced repercussions on sample composition and analysis. As the gas cools, its components may undergo condensation or phase changes, altering the overall composition of the sampled gas. Such changes can lead to inaccurate analytical results and a skewed representation of the true gas composition.

Additionally, the alteration in temperature can directly impact the hydrocarbon dew point, further complicating the measurement accuracy. To mitigate the Joule-Thomson Effect’s adverse influence, strategies such as preheating and post-heating the gas, and implementing multi-stage pressure reductions, are employed to maintain a stable and representative sample.

Hydrocarbon Dew Point

The Hydrocarbon Dew Point is the temperature at which the hydrocarbon components of a gas mixture start to condense out of the gaseous phase. This parameter is essential in the natural gas industry, as it affects the quality and usability of the gas for various applications, from production to distribution.

The Hydrocarbon Dew Point has a direct bearing on the phase behavior of the gas. Failure to account for its effects during sampling can lead to inaccuracies in gas analysis. If the sample temperature is not adequately managed and kept above the hydrocarbon dew point, condensation can occur within the sample, altering its composition. This shift can skew analytical results, undermine the accuracy of measurements, and pose challenges in determining gas quality.

Proper Sample System Design

Designing an effective and accurate gas sampling system is crucial to obtaining reliable data for analysis. Several vital components play a role in achieving representative and precise gas samples. Careful consideration is required when selecting the sample source, determining the sample location, and choosing the appropriate sample probe type and design.

Vital Components for Accurate Gas Sampling

Sample Source: The source of the gas sample plays a fundamental role in determining its accuracy and representativeness. Factors such as pressure, temperature, and phase must be considered to ensure that the sample collected truly reflects the gas being analyzed.

Sample Location: The location within the piping system should be carefully chosen to ensure a fast response time, proper pressure and temperature profiles, and minimal interference with the gas composition. The sample should be taken from a location that best represents the flowing gas stream, avoiding obstructions, pressure drops, and other factors that could distort the sample.

Sample Probe Type and Design: The probe is responsible for extracting the gas sample from the source. The type of sample probe should be chosen based on the specific requirements of the sampling process. Options include direct mount probes, retractable probes, non-membrane probes, membrane probes, and self-cleaning probes.

The design of the sample probe includes considerations for mounting, length, and placement within the piping system. Mounting vertically at the top of a straight run of horizontal pipe and calculating the correct probe length to avoid vibration-related failures are essential steps.

Pressure Regulator: Pressure regulators reduce the sample pressure to a suitable level for analysis. This step is crucial to prevent damage to the sampling equipment and to maintain consistent conditions.

Sample Line: The sample line transports the reduced pressure gas from the sample point to analytical devices. The choice of tubing material, diameter, and insulation ensures minimal sample distortion during transportation.

Analytical Devices: Instruments like gas chromatographs, moisture analyzers, hydrogen sulfide analyzers, and others are essential for analyzing the sample’s components and characteristics.

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Filter and Pressure Regulation

Filters and pressure regulators play pivotal roles in ensuring the reliability and representativeness of gas samples. These components are critical for maintaining the integrity of the sampled gas and for ensuring precise analysis.

Role of Filters and Liquid Separators

Filters and liquid separators are instrumental in preventing particulate matter and free liquids from entering the gas sample. These unwanted contaminants can distort the composition and characteristics of the gas being analyzed. Removing these impurities, filters, and separators helps maintain the sample’s accuracy and representativeness.

Effective Pressure Regulation Techniques

Uncontrolled pressure variations can lead to sample distortion, equipment damage, and inaccurate analysis. Employing effective pressure regulation techniques involves reducing the sample’s pressure to a level suitable for analysis. This can be achieved using precision pressure regulators, ensuring the gas remains within the required parameters.

Pre/Post Heated Regulators for Precision

In scenarios where the gas sample is subject to temperature fluctuations or dew point concerns, pre/post-heated regulators come into play. These regulators have heating elements that allow them to maintain the gas temperature within specific tolerances. By preventing the gas from condensing or changing phase during the pressure reduction process, pre/post-heated regulators contribute to accurate and consistent analysis.

Sample Line and Speed Loop

Heat Trace Tube Bundles for Temperature Control

Maintaining a consistent temperature along the sample line is crucial, especially when dealing with gases prone to phase changes or condensation. Heat trace tube bundles, equipped with electric heating elements, offer a solution for precise temperature control. By preventing temperature variations that can alter the gas composition, these bundles ensure that the sample remains representative throughout its journey from the source to the analyzer.

Ensuring Fresh Samples with Speed Loop Devices

To ensure that the gas sample reaching the analytical devices is fresh and representative, speed loop devices play a significant role. These devices maintain a continuous and controlled flow of regulated sample gas from the sample point to the analyzer. By providing a constant supply of fresh gas, speed loop devices prevent potential sample contamination or degradation if the gas has been stagnant for an extended period.


Sample conditioning systems are the unsung heroes of accurate gas analysis, offering a range of invaluable benefits. These systems enhance precision by preparing gas samples meticulously, ensuring that the data generated is both reliable and trustworthy. In navigating complexities like the Joule-Thomson Effect and the Hydrocarbon Dew Point, they shield against inaccuracies, promoting reliable insights.

Beyond precision, these systems bolster safety and compliance, safeguarding against critical components and ensuring adherence to contractual and regulatory obligations. By optimizing equipment longevity and customizing solutions to industry-specific demands, sample conditioning systems elevate the entire gas analysis process to new heights of reliability.