This document aims to simulate the mechanical loads that could be imparted to passive fire protection (PFP) materials and systems by explosions resulting from releases of flammable gas, pressurised liquefied gas or flashing liquid fuels that may precede a fire. This document can also be applicable to dust explosions. Gas explosions can give rise to pressure and drag forces. Damage to PFP materials in a gas explosion can be caused by the direct effects of pressure and drag loadings and by the deflection of the substrate supporting the PFP material. Other parts of the ISO 23693 series will deal with a range of common types of specimen that could be tested against the mechanical loads generated.