Iran Occupational Health

Background and aims: Leakage of toxic and hazardous substances in the chemical and process industries always had been one of the factors threatening the workers and residents of the industries. The purpose of this study is modeling of hexane emissions planning emergency response program.

Methods: In this study we describes the factors affecting discharging release of material and ALOHA software used as one of the best software for modeling emissions from storage tank 579 thousand gallons of hexane, in a petrochemical. And based on modeling results emergency response plan in sudden devastation of hexane tank prepared and presented.

Result: The results of modeling toxic vapor cloud formation caused by the release of hexane and form liquid pools around tank (scenario 1) showed that the diameter of pool formed was 200 m. And about 140 meters around tank concentration of hexane is 8600 PPm (range AGEL-3) that there is risk of death and life-threatening in people that are in the area. Distances up to 160 meters of tank, concentration of hexane is 7200 ppm that is about 60% of the Lower explosive limit (LEL) in gas-hexane. To 526 meters of hexane tank, concentration of hexane is 1200 ppm that is about 10% of the Lower explosive limit (LEL) of hexane gas. In explosion of toxic vapor cloud up to 133 meters away from the tank area is 8 psi, and to a distance of about 196 meters of tank, the blast wave pressure is 3 Psi. In the event of scenario 2 (hexane emissions from tank associated with the burning) thermal radiation from a distance of 353 meters of the tank is 10KW / sqm and to 491 meters of away from tank thermal radiation is 5 KW / sqm. BELEVI and tank explosive occurring (scenario 3) leads to the formation of a fireball with 640 meters diameter in 31 seconds time, and the amount of thermal radiation to 1.3 km from tank is 10KW / sqm.

Conclusion: Hexane toxicity is the most serious consequences of danger that threatening the personnel. Therefore preparation of emergency response plan will have an important role in limiting the harmful effects in release of toxic and hazardous substances.