Control Stop on the fly

Have any of you changed a Sloan Regal or Royal control stop out without shutting the supply off? I now work in a hospital and to my suprise valves are few and far between. I cant even stick my head up into the cieling to find one because removing a tile requires about 3 meetings, 2 hours of paper work and air testing...its a big deal and coming from working in construction is really frustrating. An example would be using my screw driver to turn off the stop and the stop breaking and springing a leak flooding out patient room because nobody can get to a shutoff valve. Id rather have a small flood than a big flood so Any tips, tricks, advice?

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