Mariog,

I have seen some companies use an expression in lieu of the (Pexit-Patm)* Exit Area ( for the Reaction force at the open end of an PSV tail pipe) :

Force= mass flow rate times SQRT( GAMMA *g*R1*T2)/g

where GAMMA is the ratio Cp/Cv, R1 is gas constant, g=acceleration due to gravity , T2= Max. Exit temp.

I am not sure how is this expression derived.

Kind help from Mariog/any member of this forum will be highly appreciated.

Regards