Float switches are used to control electrically driven
pumps and regulate liquid levels in tanks.
In a tank installation (fig. 2-36), the deck and
overhead flanges are welded to the deck and overhead
of the tank. The float guide rod, E, fits into the bottom
flange and extends through the top flange. The float
guide rod then passes through an opening in the switch
operating arm. Collars A and B on the guide rod exert
upward or downward pressure on the operating arm as
the float approaches minimum or maximum depth
positions. The switch operating arm is fastened to the
shaft, which is coupled to the switch contact mechanism
Figure 2-35.--A limit switch, roller actuator arm operated.
Figure 2-36.--A float switch tank installation.