A headbox apparatus for a papermaking machine is disclosed. The appliance includes a sensor disposed in-line to an incoming flow of water received from the incoming water valve and is configured to sense a degree of hardness in the incoming flow of water. The shell defines a receiving room, a first opening and a second opening and includes an integrally formed enclosure enclosing the receiving room and a first flange outwardly protruding from the enclosure. The alarming section issues a supervision voltage level alarm when the detected voltage of the battery drops to a supervision voltage level different from the lowest operation voltage level. This will enable the input image to be displayed on a display with a lower bit depth.