What is split-range control and where is it applied?

Split-range control uses a single controller output to manipulate two or more final control elements sequentially over different portions of the output range. Example: pressure control using a vent valve (0-50% output) and supply valve (50-100% output) - as controller output increases, first vent closes then supply opens. Applications include temperature control with heating and cooling, pressure control with supply and vent, and pH control with acid and base addition.