ISO 1928:2025

Overview

ISO 1928:2025 - "Coal and coke - Determination of gross calorific value" specifies a standardized laboratory method for measuring the gross calorific value (higher heating value) of coal and coke. The method uses a combustion-vessel calorimeter at constant volume with a reference temperature of 25 °C, and requires calibration by combustion of certified benzoic acid. Results are reported as the gross calorific value of the analysis sample with combustion water returned to liquid form. The standard also gives procedures and formulae to convert to net calorific values (constant volume and constant pressure).

Key technical topics and requirements

• Scope and principle
  • Determination of gross calorific value at constant volume; explanation of net calorific value in practical (atmospheric) combustion conditions.
• Calibration
  • Calibration of the calorimeter using certified benzoic acid; calculation of effective heat capacity and valid working range.
• Apparatus and reagents
  • Requirements for calorimetric instruments and specified reagents (benzoic acid as calibrant).
• Sample preparation and test procedure
  • Preparation of the analysis sample; assembly and operation of the combustion vessel calorimeter; measurement and correction of temperature rise.
• Calculations and reporting
  • Formulae for gross and net calorific values, expression of results, and procedures to calculate values on different bases.
• Instrument-specific guidance
  • Annex A–C: procedures for adiabatic, isoperibol/static-jacket, and automated calorimeters.
• Checklists, examples, and safety
  • Annex D: checklists for test design and procedures; Annex E: worked calculation examples; Annex F: guidance on safe use, maintenance, and testing of combustion vessels.
• Precision
  • Clauses on repeatability and reproducibility limits for laboratory measurements.

Note: The document contains an explicit safety warning regarding the risk of explosion or blow-out of combustion vessels - strict adherence to the specified provisions is required.

Applications and who uses it

ISO 1928:2025 is applied by:

• Analytical laboratories performing fuel quality testing
• Coal and coke producers and traders for product specification and contractual testing
• Power generation and steel industry quality/control departments
• Regulatory agencies and certification bodies setting energy content standards
• Research institutions studying fuel combustion and energy balance

Practical benefits include consistent, traceable calorific value measurements, comparability across labs, and validated procedures for instrument calibration and safe operation.

Related standards (if applicable)

The standard references related instruments and analysis standards such as:

• ISO 651, ISO 652 (calorimeter thermometers)
• ISO 687 (moisture in coke)
• Other referenced test-method standards cited within ISO 1928:2025

Keywords: ISO 1928:2025, gross calorific value, coal, coke, calorimeter, benzoic acid calibration, net calorific value, combustion vessel, calorimetry, fuel testing, laboratory standard.