radiant heat(Tank fire / Leakage fire)

There are various methods for calculating radiant heat, as shown in the table below, and our program can perform calculations using any of these methods. However, we recommend the "Mudan method" described in the NFPA Handbook as the most practical method.

In methods other than NISTIR6546, the radiant exitance is taken as the average value over the entire flame height.
The actual state of the flame is that the lower part near the oil surface burns brightly, while above it is mostly smoke with occasional flickers of red flame. NISTIR6546 calls this bright area the Luminous Band, and assumes that its radiant dispersibility is approximately 100 [kW/m2] regardless of the type of oil, and provides a formula for calculating the height of that area.
While the radiation intensity at points several times the tank diameter can be measured using the mean radiation exitance method, the luminous band concept seems more practical for areas closer to the tank.

item	Industrial complex Safety and disaster prevention technical guidelines KHK-E007-1974	petrochemical complex Disaster Prevention Assessment Guidelines (Fire and Disaster Management Agency Special Disaster Office)	NISTIR6546 (National Institute of Standards and Technology, USA)	Mudan method (NFPA Handbook)
Wind conditions	Only under windless conditions	Only under windless conditions	Calm and windy	Calm and windy
heat receiving surface	Vertical surfaces only	Vertical surfaces only	You can select the "maximum heat-receiving surface angle" and either "vertical" or "horizontal".	You can select the "maximum heat-receiving surface angle" and either "vertical" or "horizontal".
Height of the flames	1.5D	1.5D	The height of the luminous band is calculated from the tank diameter and the physical properties of the fuel.	Calculated from the tank diameter and the physical properties of the fuel (using a different formula than NIST)
Radiation divergence	"Actual measured values of the target fuel" or "Calculation formula specified in the guidelines"	"Measured values of the target fuel" Furthermore, it is stipulated that the radiant extinction should be multiplied by a "reduction rate" (a reduction rate of 0.3 is used in the program because the calculated value deviates significantly from the actual value).	"Constant" regardless of fuel	"Measured values of the target fuel" or "Calculated using a method specific to the Mudan method"
Features	Because the flame height is kept constant by the ratio of the diameter, when the tank diameter increases, the flame height is overestimated, resulting in a higher radiant heat calculation result than the actual value.	Aside from the concept of reduction rates, it is the same as the "Technical Guidelines for Safety and Disaster Prevention in Industrial Complexes KHK-E007-1974". This results in an underestimation of radiant heat, making it appear safe everywhere.	A reasonable result can be obtained regarding the radiant heat near the burning tank during firefighting operations.	It's practical because you can input the radiative exitance, and the calculation results will differ depending on the physical properties of the fuel.