Smoke and Gas Ingress Analysis (SGIA) is a study of the smoke and gas engulfment hazardous events which leads to the impairment of non-process buildings, temporary refuge, escape & evacuation routes.

SGIA Objective:

The objective of the smoke and gas ingress analysis is to study the concentration of smoke and gas ingress into the non-process buildings and measure it against the concentration levels that affects personals.

SGIA Study Approach:

1.  Identify the hazards capable of causing smoke or a flammable gas cloud.
2.  Consequence analysis of smoke and/ or gas ingress using FLACS software, i.e determine the   
   smoke or gas concentration outside and inside the building /TR.
3.  Assess the impairment time of all the events which causes impairment.
4.  Review the prevention and mitigation systems that could reduce the potential for ingress.
5.  Assess the evacuation time

Modelling Approach

A ventilation model: This uses data from a building/TR pressurization test in conjunction with geometry and weather information to estimate the air change rate for the building/TR under shutdown conditions.

An infiltration model to determine the accumulation of pollutants over time as a function of external concentration and the air change rate.

A toxicity model to determine the effects of pollutants on the occupants and hence the impairment time.

SOFTWARE used for the study

The simulations will be performed with the latest version of the FLACS tool (version 9). FLACS is a well-known and thoroughly validated tool developed for ventilation, dispersion and explosion simulations in complex geometries. FLACS is developed and maintained by GexCon AS in Norway. 

Inputs Required for the study

1. CAD geometrical model of the installation.
2. Plot Plan/Layout (with scale)
3. Piping and Instrumentation Diagrams (P&IDs)
4. Piping general assembly drawings
5. Aerial snapshot of site (preferably high resolution) or Google Earth coordinates
6. Facility Description
7. Operating Manual
8. Heat & Mass balance Sheet
9. Process Description
10. Process Flow Diagram
11. Cause and Effect Diagram
12. Emergency Shutdown Philosophy
13. Site Meteorology- Wind speed and direction & Atmospheric stability conditions
14. Ignition sources-Onsite and Offsite ignition sources