Uses a float and counterweight system to convert water level into an electronic output that can be read by a datalogger. Accurate to within a millimetre over a wide range.

The 6541 can resolve a water level change as small as 0.2mm and is one of the most accurate ways to monitor water levels to millimetre accuracy. It maintains this accuracy for the service life of the instrument, without calibration or maintenance.

The instrument displays water level on an LCD display on the front panel and provides an electronic SDI or 4-20mA current loop output for connection to a data recorder.

It senses the position of the water surface using a float and counterwight system. As the water level changes, the float position changes. This change is coupled, via a beaded float wire, to a pulley attached to the shaft of the optical encoder. The shaft rotates as the water surface and float move up and down and the position of the water surface is encoded as a number. Up/down buttons, located behind the front lid, allow you to set this number so that the Hydrologger outputs actual water level.

NIWA Contacts