ISO 24678-6:2026 Fire safety engineering — Requirements governing algebraic formulae — Part 6

Basic Standard Profile

Full Title: Fire safety engineering — Requirements governing algebraic formulae — Part 6: Flashover-related phenomena

Edition: 2nd edition, published August 6, 2026, superseding ISO 24678-6:2016

Technical Committee: ISO/TC 92/SC 4 (Fire Safety Engineering Subcommittee)

ICS Code: 13.220.01 (General fire protection)

Standard Positioning: A branch document within the ISO 24678 series, which executes the general provisions laid out in ISO 24678-1 specifically for flashover calculation scenarios

ISO 24678-6:2026 sets out core requirements for applying explicit algebraic formulae to compute key characteristics of flashover inside enclosed spaces. As a constituent part of the ISO 24678 series, it unifies assessment methodologies for tracking the initiation and progression of flashover — a defining phase of compartment fires — for global fire safety engineering professionals. This standard works to align cross-border calculation practices, underpin performance-oriented fire safety design, and deliver clear guidance on input parameter definition, valid application ranges and selection restrictions for relevant formulae.

Core Covered Topics

1. Flashover Definition and Characteristics

Flashover refers to the instantaneous full-surface ignition and sustained combustion of all combustible contents within an enclosure fire.

Distinguished by drastic heat accumulation and accelerated fire spread, it marks the pivotal shift from the early growth stage of a compartment fire to the high-hazard post-flashover phase.

2. Mandatory Rules for Algebraic Formulae

Core input parameters including enclosure geometric dimensions, opening factors and thermal attributes of lining materials must be clearly defined prior to calculation.

Both empirical and theoretical algebraic formulae fall under regulatory constraints, with a mandatory requirement that all formula derivation can be traced back to credible experimental datasets and proven scientific fundamentals.

Baseline application limits are specified: the formula set is primarily applicable to regular rectangular enclosures under standard atmospheric conditions, with non-combustible interior linings.

3. Standardized Calculation and Documentation Process

Stepwise calculation workflows are provided to estimate the minimum heat release rate sufficient to trigger compartment flashover.

Practitioners are required to select appropriate formulae in accordance with actual project conditions, such as natural or mechanical ventilation patterns and varied building construction categories.

Practical calculation examples and formal documentation guidelines are included to ensure full traceability and transparency of fire safety design deliverables.

4. Input Parameters & Applicability Boundaries

Key calculable variables covered in the standard:

Opening factor (calculated from vent area and vent height)

Total internal surface area of the enclosed compartment

Thermal inertia of building structural materials

Every included formula has explicit limits on permissible enclosure size, geometry and structural material properties to avoid misuse outside valid application boundaries.

Primary Application Scenarios

Fire Safety Engineering Design

It serves as a practical technical reference for engineers designing new buildings, marine vessels and vehicles, as well as conducting fire safety audits for existing assets. It standardizes flashover prediction routines for performance-based fire analysis, and supports quantitative screening and justification of fire protection measures based on heat release rate thresholds and compartment layout conditions.

Regulatory Compliance and Peer Review

It standardizes calculation logic for code conformity inspections, official project approvals and safety certification procedures. Harmonized documentation terminology and workflows streamline independent peer technical reviews and official regulatory audits.

Risk Assessment and Design Scenario Comparison

It allows rapid verification of proposed designs against established flashover risk thresholds, and facilitates direct comparison between different fire safety design schemes via uniform, internationally accepted calculation methods.

Reference Standards

ISO 24678-1: General requirements for algebraic formulae applied in fire safety engineering

ISO 24678-4: Standard covering smoke layer analysis for compartment fire modelling

ISO 23932-1: Overarching methodological framework for performance-based fire safety engineering

ISO 13943: Universal fire safety vocabulary that defines industry-wide core concepts and parameters

ISO 16733-1, ISO 16733-2: Standards for vent flow calculation, a critical input for flashover evaluation

Closing Summary

Implementing ISO 24678-6:2026 enables consistent, robust evaluation of flashover-related fire behaviours, boosting the reliability and openness of fire safety engineering designs worldwide. It is an indispensable practical resource for professionals delivering performance-based fire safety objectives, simplifying design record-keeping and aligning project execution with global best practices for enclosed space fire analysis.