Overview
ISO 10101-1:2022 establishes the general requirements for determining water content in natural gas using the Karl Fischer method. This internationally recognized standard enhances measurement accuracy by specifying fundamental principles, sampling procedures, and uncertainty evaluation for water determination. It serves as Part 1 of a series, complemented by ISO 10101-2 and ISO 10101-3 that detail volumetric and coulometric procedures, respectively.
The Karl Fischer method offers a selective, rapid, and precise technique for moisture analysis in natural gas - essential for ensuring gas quality, safety, and efficiency in processing, transport, and end-use applications.
Key Topics
-
Scope and Application: Defines the purpose of determining water concentration in natural gas via Karl Fischer titration, applicable to both volumetric and coulometric techniques.
-
Principle of Method:
- Based on the stoichiometric reaction of water with iodine and sulfur dioxide in a methanol solution.
- Water quantity is derived from iodine consumption, measured either by titration (volumetric) or electrochemical generation of iodine (coulometric).
- Volumetric titration suits water amounts from 1 mg to 100 mg; coulometric titration targets smaller amounts from 10 µg to 10 mg.
-
Chemical Reactions and Interferences:
- Detailed key reaction mechanisms and the impact of interfering gases like hydrogen sulfide and mercaptans, with correction formulas for interference mitigation.
- Guidance on identifying and quantifying interfering sulfur compounds to ensure precise water measurement.
-
Sampling Requirements:
- Highlights the necessity of maintaining sample integrity by keeping gas temperature above dew point and using inert materials.
- Recommends sampling procedures aligned with ISO 10715 to prevent moisture loss or contamination.
-
Measurement Uncertainty:
- Emphasizes estimating measurement uncertainty using interlaboratory comparisons (ISO 5725-2) and evaluation guidelines (ISO 21748).
- Suggests reporting expanded uncertainty with a coverage factor k=2 for reliable results.
- Incorporates the importance of including sampling uncertainty in the total uncertainty budget.
Applications
-
Natural Gas Industry: Monitoring and controlling moisture levels to prevent pipeline corrosion, hydrate formation, and equipment damage.
-
Gas Quality Assurance: Ensuring compliance with gas specifications for both transmission companies and end users.
-
Laboratory Analysis: Development of standardized procedures for routine moisture testing in natural gas samples.
-
Environmental and Safety Compliance: Moisture determination to assess gas safety parameters and reduce risks associated with impurities.
-
Process Optimization: Utilizing accurate water content data to improve gas processing operations and efficiency.
Related Standards
-
ISO 10101-2: Specifies the volumetric titration procedure for water determination in natural gas.
-
ISO 10101-3: Details the coulometric titration method adapted for low water content measurements.
-
ISO 10715: Provides general guidelines for natural gas sampling essential for water analysis.
-
ISO 14532: Natural gas vocabulary ensuring consistent terminology in moisture analysis and related testing.
-
ISO 5725-2: Establishes protocols for evaluating repeatability and reproducibility of measurement methods.
-
ISO 21748: Offers guidance on using repeatability and reproducibility data to estimate measurement uncertainty.
-
ISO 19739: Covers determination of sulfur compounds in natural gas, relevant for interference correction.
Keywords: ISO 10101-1, natural gas, water determination, Karl Fischer method, moisture analysis, volumetric titration, coulometric titration, sampling, measurement uncertainty, gas quality, sulfur compound interference.
Open preview (PDF)Natural gas — Determination of water by the Karl Fischer method — Part 1: General requirements