3097 EI Research Report: Dispersion modelling and calculations in support of EI Model Code of Safe Practice Part 15: Area classification code for installations handling flammable fluids

Overview:

Provides the findings of additional research to further extend the dispersion modelling and calculation basis of EI Model Code of Safe Practice Part 15 Area classification code for installations handling flammable fluids (EI 15). It focuses on the following technical issues:

• Sensitivity analysis of ambient temperature, relative humidity, weather and surface roughness on dispersion characteristics from point sources for various fluid categories.
• Sensitivity analysis of the nature and ambient temperature of the underlying surface (e.g. concrete, dry soil), weather, and surface roughness on dispersion characteristics from pools of various diameters and depths, for various fluid categories.
• Determination of whether any existing EI 15 fluid categories apply to liquefied natural gas (LNG), or if it requires specific modelling and sensitivity analysis of parameters (hole diameter, release pressure, temperature, relative humidity, weather, surface roughness, surface type) to determine dispersion characteristics.

Given that the new research augments, but does not invalidate, several technical issues in the first edition, and that no further technical work has been carried out on other work items, the first edition of the report is entirely replicated as Addendum 1.

The findings of the report will be reviewed by the Energy Institute's Area Classification Working Group to see how the new research affects the continuing technical integrity of pertinent aspects of the third edition of EI 15.

The information in this publication should assist process safety engineers, safety advisors, designers, or others with responsibility for hazardous area classification to better determine the extent of hazardous areas in a consistent manner for specific fluid and process, weather and environment dependent values. The information is internationally applicable provided it is read, interpreted and applied in conjunction with relevant national and local requirements.