ISO 7404-5:2025 PDF

Coal — Methods for petrographic analysis — Part 5: Method of determining microscopically the reflectance of vitrinite

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Title (English):

ISO 7404-5:2025

Coal — Methods for petrographic analysis — Part 5: Method of determining microscopically the reflectance of vitrinite

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 15
Publication date:: October 27, 2025
Edition:: ISO IS 7404 edition 4 version 1
ICS:: 73.040

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Description (English):

This document specifies the methods for determining the reflectance of vitrinite of coals microscopically on polished surfaces, immersed in oil. The methods are applicable to coals from single seams or coal blends covering the whole range of low-, medium- and high-rank coal. Vitrinite reflectance measurements can be used to characterize the components within blends. Measures can be taken to correct for the vitrinite percentage within each of the components of the blend or to determine the proportion of components in a blend, particularly when the components have dissimilar vitrinite contents. This method necessitates the identification of vitrinite by the analyst. Reflectance measurements on vitrinite, obtained by interpreting the results from an automated system, are outside the scope of this document.

Technical details

Technical committee: ISO/TC 27/SC 5 - Methods of analysis
SKU: ISO 7404-5:2025

Abstract

Overview

ISO 7404-5:2025 - "Coal - Methods for petrographic analysis - Part 5: Method of determining microscopically the reflectance of vitrinite" specifies a microscope-based procedure to measure vitrinite reflectance on well‑polished coal surfaces immersed in oil. The method is applicable across the full range of low-, medium- and high‑rank coals and to single‑seam coals or coal blends. Measurements are performed at 546 nm and compared against calibrated reflectance standards. Automated interpretation of reflectance data is explicitly outside the scope.

Key topics and technical requirements

Measurement principle: Near‑normal incidence light reflected from vitrinite in oil is measured (photomultiplier or equivalent) at 546 nm and compared with standards.
Immersion medium: Non‑drying, non‑corrosive oil with refractive index 1.5180 ± 0.0004 at 23 °C and 546 nm; avoid old or contaminated oil.
Calibration standards: Use at least two polished, durable, isotropic standards with well‑spaced reflectances; additional standards needed for reflectance > 2.0%.
Measurement types: Supports maximum and random reflectance determinations - the chosen type must be reported.
Sample preparation & apparatus: Polished surfaces and optical alignment as described; see ISO 7404-2 for sample preparation procedures.
Quality checks: Procedures for apparatus stability, linearity, parasitic reflections and calibration verification are specified.
Analyst identification: Vitrinite must be identified by the analyst; results derived solely from automated interpretation are excluded.
Reporting & precision: Requirements for reporting results, repeatability and reproducibility data, and test reporting are included.

Applications and users

Practical uses of ISO 7404-5:2025:

Determination of coal rank for geological or technical classification.
Characterization of coal blends, including correction for vitrinite content or estimation of component proportions when components differ in vitrinite reflectance.
Quality control in coal production, trading and transport (cargo characterization).
Feedstock assessment for coking, combustion, gasification and coal conversion processes.
Research and accreditation (e.g., ICCP Single Coal Accreditation Program) for petrographers and analytical laboratories.

Typical users:

Coal petrologists and petrographic laboratories
Power and steel industry quality/control teams
Coal traders and commodity analysts
Academic and geological researchers

Related standards

ISO 7404 series (petrographic methods)
ISO 7404-1 (Vocabulary)
ISO 7404-2 (Sample preparation)

Keywords: ISO 7404-5:2025, vitrinite reflectance, coal petrographic analysis, immersion oil, reflectance standards, coal rank, coal blends, photomultiplier, polished surfaces.

Related standards

Standards mentioned in the description

Abstract

Overview

Key topics and technical requirements

Measurement principle: Near‑normal incidence light reflected from vitrinite in oil is measured (photomultiplier or equivalent) at 546 nm and compared with standards.
Immersion medium: Non‑drying, non‑corrosive oil with refractive index 1.5180 ± 0.0004 at 23 °C and 546 nm; avoid old or contaminated oil.
Calibration standards: Use at least two polished, durable, isotropic standards with well‑spaced reflectances; additional standards needed for reflectance > 2.0%.
Measurement types: Supports maximum and random reflectance determinations - the chosen type must be reported.
Sample preparation & apparatus: Polished surfaces and optical alignment as described; see ISO 7404-2 for sample preparation procedures.
Quality checks: Procedures for apparatus stability, linearity, parasitic reflections and calibration verification are specified.
Analyst identification: Vitrinite must be identified by the analyst; results derived solely from automated interpretation are excluded.
Reporting & precision: Requirements for reporting results, repeatability and reproducibility data, and test reporting are included.

Applications and users

Practical uses of ISO 7404-5:2025:

Determination of coal rank for geological or technical classification.
Characterization of coal blends, including correction for vitrinite content or estimation of component proportions when components differ in vitrinite reflectance.
Quality control in coal production, trading and transport (cargo characterization).
Feedstock assessment for coking, combustion, gasification and coal conversion processes.
Research and accreditation (e.g., ICCP Single Coal Accreditation Program) for petrographers and analytical laboratories.

Typical users:

Coal petrologists and petrographic laboratories
Power and steel industry quality/control teams
Coal traders and commodity analysts
Academic and geological researchers

Related standards

ISO 7404 series (petrographic methods)
ISO 7404-1 (Vocabulary)
ISO 7404-2 (Sample preparation)

Keywords: ISO 7404-5:2025, vitrinite reflectance, coal petrographic analysis, immersion oil, reflectance standards, coal rank, coal blends, photomultiplier, polished surfaces.

ISO 7404-5:2025 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Applications and users

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Applications and users

Related standards

Related standards

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