Valve characteristics define how much the valve opening or Cv changes as the stem is stroked throughout its rated travel. Valves using large blunt-ended plugs usually achieve most of their flow during the first 30% of their stroke, are usually used for on/off non-throttling service, and exhibit large full open Cv’s.

As the shape of the plug becomes sharper and extends into the seat area, the flow becomes more linear and the full open Cv usually decreases. Most 3-way valves have fairly linear characteristics.

Equal percentage is probably the most common throttling characteristic, and offers a more gradual change in Cv over the first 40% of valve travel.