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[emma14778]

Hi Everyone,

 

I am trying to calculate the maximum allowable leakage through an EBV that prevents a hazardous release. My leakage criteria is 10xERPG3 at 10ft or 50% LFL at 10ft. 

 

I had planned on using the gaussian plume model to calculate concentration at a distance of 10ft, at ground level and in the direction of wind; C(10ft,0,0). I have used this as an estimation for dispersion in other scenarios before but have always been looking at distances >50m. 

 

It is my understanding that the pasquill gifford dispersion coefficients are highly inaccurate at near field distances. Since I am only looking at a distance of 10ft I am concerned this method will not be acceptable. I am not looking for precise calculation as much as conservative calculations.

 

Does anyone have experience using the gaussian plume model for near field distances or have any recommendations for alternate models I can research?

 

Note: I know AICHE's RAST tool has a maximum allowable leakage rate for similar criteria (50% LFL or time scaled 10minute LC-50 both at 3m). I haven't used the tool myself but would be interested in knowing how they approached the calculations if anyone is familiar.

 

Cheers,

Emma