Okay, I've gotten this item & tried it out, and it is an item that you combine with the fire hose. Apparently, in some BETA version of RE3, you got a damaged Fire Hose of some kind, and you had to find this before you could put the fire out. (The Fire Hose you combine it with looks just like the normal one, except one end of it is cut off.)

Eventually, I'll get around to posting some screenshots of the other fire hose, along with all the other BETA items.