The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate. A greater restriction in flow will create a larger pressure drop across a device and thus a smaller flow coefficient, conversely device with little restriction in flow will have a small pressure drop and a larger flow coefficient. For example, the flow coefficient of a 1" ball valve may be 80 while a similarly sized globe valve in the same application may be 10.