Hello to everybody

My query is about the relief load synthesizer.
I have read Caesar manual and TR and other post here, but i cannot found the equation used by Caesar to calculate de Thrust at valve pipe/vent pipe interface.
Assuming F=Q.V+AP, sonic conditions at throat, and a isentropic evolution from stagnation, i have a flow mass rate of 74.33 kg/seg, and a force F= 3921 kg. Assuming DLF=2,
my F = 7842 kg. And this is consistent with the API 520 formula.

When i calculated with Caesar relief load synthesizer, I have:

Thrust at Valve Pipe/Vent Pipe Interface = 7259.24 kg

Is the Thrust at Valve Pipe/Vent Pipe Interface affected by a DLF= 2 ?
Why Caesar calculate a lower flow rate?
Can you tell me the equations used?
I just know that Caesar assume sonic conditions at throat, isotherm properties of gas from valve orifice to vent stack shock wave, adiabatic expansion from shock wave thru vent stack, and some other considerations showed in a COADE seminar, but isn’t explained the equation.

I hope I have been clear.
Thank you very much for your help