Can this be used to prevent backup of water to a ground floor condo kitchen sink by placing it after the P-Trap and before the exterior wall?

Minimum opening pressure 2 PSI. If this is a normal sink drain in kitchen or bathroom, water runoff will not be enough to crack open valve. Plus if the P32S is use in a kitchen or bathroom sink application, the spring mechanism would be acceptable to clogging from food, hair, etc. The P32S is used to prevent backflow normally on a pressure line, not for a waste line. He needs a swing disc back flow preventer which we do not have in PVC. A G31 is a swing disc back flow preventer for example. Thank you for your inquiry.