Question

why might leak testing with nitrogen be preferable to using R-22 ?

Answer 1

R-22 is Hydrochloroflourocarbon - HCFC, this can replace oxygen and can prove fatal when inhaled and when no ventilation is there. Also HCFC affects the ozone layer, basically depletes it. When small quantities are inhaled this may result in head ache and dizziness.

On the other hand we have Nitrogen which is inert and also present in abandance in atmosphere so doesnot affect when inhaled.

Hence for leak testing, for Environmental protection and to prevent Health problems, Nitrogen is preferred to using R-22.