Quarter turn valve
A category of valves which require just a 90 degree turn of the stem to move from the fully open to the fully closed positions. Typical examples of these being; ball, butterfly, and plug type valves.
When a valve has a quick opening trim, it has a flow characteristic that provides maximum change in flowrate at low travels. The valve curve is basically linear throughout the first half of the valve travel, it then flattens out bringing little increase in flowrate as travel approaches the wide open position.