Pressure exerted when a solid or liquid is in equilibrium with its own vapour. It is a function of the substance and of the temperature.
Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global Standards
Vapour pressure is the equilibrium pressure of the saturated vapour above a liquid expressed in Pascals (Pa) at a specified temperature.
Source: Resolution MEPC.119(52), 2004 amendments to the International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk (IBC Code), 15 October 2004, International Maritime Organization. Regulatory Guidance