When a Micro-flow of a viscous fluid or with a high differential pressure is controlled, the fluid flow in the valve
apt to become laminar. In general, valve capacities are
defined assuming that the flow in the valve is turbulent.
Therefore, it should be noted when selecting a valve size
that the valve capacity may become insufficient unless a
certain correction factor is taken into consideration for
applying the basic a Cv calculation formula for size
calculation at a laminar flow range. For model VSM Micro-
flow Control Valves, a particular sizing system is used.