Suds-N-Flood Tamer, Backflow Control
prevent  backflows in any type of sewage system. An efficient alternate solution where check or flap valves are not appropriate.

American Society of Sanitary Engineering
promotion of health, welfare and better sanitary engineering principles. The organizations motto is "Prevention Rather than Cure"
Plumbing & Mechanical Online
Now you can protect your home from expensive damage caused by wastewater backups while controlling expensive installation costs, maintenance and problems associated with typical waste backwater valves.
There is a other company called General Wire and Spring  aka General Pipe Cleaners that has something that will work on 2� floor drains they do not have it listed on their web site but they do sell it, call and ask them   Drinking Water & Backflow Prevention Magazine