Thermal radiation distances shall be calculated in accordance with one of the
following:
(1) The Gas Research Institute's GRI Report 0176, “LNGFIRE: A Thermal Radiation
Model for LNG Fires,” which is also available as the “LNGFIRE III” computer
Copyright NFPA
model produced by GRI, or alternative models that take into account the same
physical factors and have been validated by experimental test data as follows:
(a) In calculating exclusion distances, the wind speed producing the maximum
exclusion distances shall be used except for wind speeds that occur less than 5
percent of the time based on recorded data for the area.
(b) In calculating exclusion distances, the ambient temperature and relative humidity
that produce the maximum exclusion distances shall be used except for values
that occur less than 5 percent of the time based on recorded data for the area.
(2) A model that incorporates the following:
(a) Impoundment configuration, wind speed and direction, humidity, and
atmospheric temperature
(b) Validation by experimental test data appropriate for the size and conditions of
the hazard to be evaluated
(c) Acceptance by the authority having jurisdiction
(3) Where the ratio of the major and minor dimensions of the impoundment does not
exceed 2, the following formula: