Slide rule for water softening calculations - needs one slide setting only to indicate regeneration frequency and minimum salt recharge

摘要

The rule combines a set of curves and logarithmic scales so that, for a selected softening plant, the requisite regeneration frequency and the quantity of salt required can be read off directly by making a single setting of the slide to relate the daily consumption of water with the hardness value of the supply. A simple, inexpensive model of the rule can be made of cardboard, in linear form, comprising an outer sleeve with inner, rectangular slide.