Indicating Butterfly Valve -Wafer is defined as a zone control valve. They are used as shut-off valves on the water supply lines to separate (control) the zones within the zone. Butterfly valve or rising stem valve is used for cutting or control purposes. The position of all valves used in fire systems must be visible and electrically traceable. Butterfly valves are gear boxed flywheel type. The monitoring switch of butterfly valves is inside the valve and has an open closed position indicator on it.