Indicator of float ball cursor, the one end that uses string of a nylon hitchs float ball, put float ball into water, drawstring other one aspect of the matter bypasses pulley is fastened toward cursor. Rise when water level, float ball rises along with water level, demonstrative cursor drops; Drop when water level, cursor rises.

Conduit connects indicator, leave in cistern bottom have one opening, receive sealedly on perpendicular vitreous canal, the other one aspect of the matter that glass manages but blurt out is direct atmosphere or receive cistern coping. Such, can see the water level of cistern from inside vitreous canal directly. In n cistern store in water type water heater, switch of water level of type of ball of commonly used still float will control cistern water level, in case excessive water. Because float ball can follow water level to rise,fall, raise certain height when float ball consequently, pass connecting rod, can make water level switch is shut, stop into water, cistern water level won't lift again.

Store water heater of water form report protects switch to be burned in order to prevent anhydrous doing of anhydrous, with protecting heater not to send overheat burn down, commonly used is hydraulic pass feeling type protector, hydraulic passing feeling type protector is a hydraulic and sensitive switch actually, right prep above or under heater water level hydraulic have taller susceptibility. Hydraulic tall, switch receives electrify source; Water depress, switch disconnects power source, make sure heater is over in water only thereby electrify of the ability below the condition of complete immersion works. Another kind is protector of electronic water level. Hydraulic the water level that passes feeling type protector to use water is different, the principle with the different also conductivity of corresponding water, get water level signal through coming to the measurement of the conductivity of water, via corresponding executive signal is being issued after enlarge, control mains switch close or disconnect.