US Patent 7051765 Balanced orifice plate

An orifice plate for use in a conduit through which fluid flows is defined by a central circular region having a radius R0 and a ring-shaped region surrounding the central circular region. The ring-shaped region has holes formed therethrough with those holes centered at each radius R thereof satisfying a relationshipAR=a/(XRVRb)whereAR is a sum of areas of those holes having centers at radius R,XR is a flow coefficient at radius R,VR is a velocity of the fluid that is to flow through the conduit at radius R,b is a constant selected to make at least one process variable (associated with the fluid that is to flow through the conduit) approximately equal at each radius R, anda is a constant that is equal to (XRARVRb) at each radius R.