Aducm355 interfaced O2 gas sensor 2 lead and 4 lead sensor correct value

This is a snapshot of example M355_ECSns_2E


avg =34626 (in our example  is equal  26238)

measure =1,23E+3

My first  question is acceptable how value, because I'm using also a 4 lead sensor and I'm write a combination code between example for 2 lead sensor  CH1,and 4/3 leads sensor CH2 where I'm using also this function :




Second question 

My target is read a value for O2  18%vol, how convert the measure value to 18%vol?.