Dear Les
You may not be able to sand the floor, but you can remove all the old finish with a chemical stripper, for more about this please read my article on this available in the search box at the top of this web page.
You may be able instead, to save the old finish, do various tests on the old finish as suggested in the second part of the floor maintenance article found in the search box at the top of this web page. And lastly be sure to read about my thoughts on the Orbital Floor sander also in the search box at the top of this web page.
You see there are many alternatives to just sanding a floor. And by the way if you do intend to strip the floor to the bare wood, and want a fast dry finish read my article on the Dura Seal 1000 water based finish.