[Consequence calculation of a leak for liquid ammonia storage tank].
OBJECTIVE
To calculate the consequence of acute ammonia poisoning accident which was caused by the leak of liquefied ammonia storage tank, so as to provide theoretical basis for working out the counterplan of accidents.


METHODS
The amount of liquefied ammonia to be reserved, the pressure and temperature inside the tank were inputted; based on the physical chemistry principle, the evaporating amount was calculated; and using the proper diffusion model, the size of ammonia cloud, percentages of death and depth range of the poisonous gas etc was calculated.


RESULTS
Assuming the leaky tank had liquefied ammonia 50 t, the pressure and the temperature were 2.5 MPa and 30 degrees C respectively, the evaporating amount and the size of ammonia cloud were calculated. The radiuses, of the ammonia released cloud of severe, moderate and mild hazard were 108 m, 216 m, 370 m respectively; if the exposured time was 30 min, the percentage of death would be 50%; if the exposured time was 5 min, the percentage would be 10%; if the exposured time was 2 min, the percentage would be 2.5%. When the stable degree of circumstance was C, the wind speed was 2.3 m/s and the outside concentration of the cloud was 4000 mg/m3, dimension of cloud in X axis was 782 m and in Y axis was 88 m.


CONCLUSIONS
The leaky consequence of liquefied ammonia was very serious. It is necessary to take preventive measures during production, storage, transportation and using of liquefied ammonia.
Zhao
Shulan
S
Section of Occupational Hygiene, Tianjin Centers for Diseases Control and Prevention, Tianjin 300011, China.
Feng
Linmin
L
D000062:Accidents, Occupational / Q000517:prevention & control*; D000641:Ammonia / Q000032:analysis* / Q000506:poisoning*; D006801:Humans; D011312:Pressure; D013696:Temperature
D000641:Ammonia