The Sloane Flushometer Valves are more common on commercial buildings.
I am sure you have seen them in public places. They are not common inside your residential house. However, allow me to ask:
A--Where is the shut-off valve? In case you need to fix some leak.
B-- Is the shut-off valve behind the wall? In another room?
C--Important: Can you please tell me of a site on the Internet where I
find manuals to learn how to fix them? Usually I do residential homes, and
very seldom I run across Sloane Flushometers.Thank You.
The shut off valve for the wet wall of toilets is wherever the plumber put it. There is no standard. However, you can check in the ceiling above the wall and see if there is one there. There is also a stop valve on the flushometer itself. Look at where the piping comes out of the wall. There is usually a cap or cap nut. Remove the cap or cap nut and you will see a slotted screw. Turn this clockwise to shut off.
As to an internet site to learn to service flushometers...I'm not sure. I guess you could try Sloan's website. However, there really isnt much to them and you could probably learn quite a bit by just taking one apart.
JDC is correct about the location of the water shut-off for the Sloan valve itself. Should you need to replace the whole valve (including valve shut-off) you will need to find to access another valve or the whole hose shut-off. Try going to Sloans website and look for a "parts list" that shows all the internal parts, in order of their location. Most common problem with them is the diaphram. There is a weep hole that can clog and prevent proper flushing. This hole can be cleaned out with a needle or other small pin.
If you have never made a mistake, you haven't done much.