I am a Respiratory Therapist & I work anywhere from 32-40+hrs a week & I am PRN (as needed). I was just wondering is there any laws stating that after so many accumlative hours or so many weeks w/ OT if there is any law or regulation that regulates the company keeping me PRN or making them go ahead & make me a FT employee? Thanks

Nope. The employer may keep you on PRN status as long as they wish to. You're free to look for full-time employment elsewhere if you wish.

No, there is no such law. They can leave you on an as-needed basis indefinitely.