Remove the displacer from the torque arm.
Apply equivalent weight on the torque arm that is equal to the wt. of the displacer. Adjust zero % output.
For Span : V = πr2h
Loss in weight = Wt. of float - wt. of the float immersed in liquid
Loss in weight = [ wt. of float - Vol. x d ]
Span wt. = (wt. of float - Loss in wt.)
r = radius of the displacer.
h = ht. of displacer.
Apply equivalent wt. equal to the (Wt. of float - Loss in weight). Adjust Span to get 100 % out put.
To check linearity apply average of the two weights.