API Screen Number
Mesh, obsolete. Mesh count, obsolete. Number in an API system used to designate the D100 separation range of a mesh screen cloth. cf. D100 separation (3.1.23). NOTE 1 The term mesh was formerly used to refer to the number of openings (and fraction thereof) per linear inch in a screen, counted in both directions from the centre of a wire. This term is being replaced by the API screen number. NOTE 2 Mesh count was formerly used to describe the fineness of a square or rectangular mesh screen cloth. For example, a mesh count such as 30 × 30 or often 30 mesh indicates a square mesh, while a designation such as 70 x 30 mesh indicates rectangular mesh. This term is being replaced by the API screen number. NOTE See 9.6 for further information.
Source: API RP 13C, Recommended Practice on Drilling Fluids Processing Systems Evaluation, Upstream Segment, Fourth Edition, December 2010. Global Standards