標準號：IS 2952 Pt.2-1975
發布日期：1975/12/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：1.1 This standard (Part II) specifies the profile, sizes and materials for cons-truction of orifice plates and nozzles and outlines procedure for measurement of flow of gases under steady conditions up to a Mach number of 0.5 at the orifice.1.2 Details of connections between primary and secondary elements are proposed to be covered in a separate standard. Further, this standard does not cover the measurement of steam, wet gases or mixtures.1.3 This standard also provides the data on discharge coefficients for use in computing the rate of flow through these devices of specified profile when direct calibrations have not been made on them and provides an example (see Appendix A) for computation of flow using the equations recommended. The discharge coefficients are applicable to the following conditions:a) Orifice Plates1) Corner tapsi) Upstream Reynolds number between 5×103 and 107, ii) Pipe diameter between 50 and 1 000 mm,iii) Diameter ratio between 0.22 and 0.8, andiv) Pressure ratio greater than 0.75.2) Vena contracta tapsi) Upstream Reynolds number between 6×103 and 107,ii) Pipe diameter between 50 and 760 mm, iii) Diameter ratio between 0.1 and 0.8, and iv) Pressure ratio greater than 0.75.3) Flange tapsi) Upstream Reynolds number between 8 ×103 and 107, ii) Pipe diameter between 50 and 760 mm, iii) Diameter ratio between 0.1 and 0.75, and iv) Pressure ratio greater than 0.75.b) Nozzles1) ISA 1932 nozzlesi) Upstream Reynolds number between 2×104 and 1.17 × 106, ii) Pipe diameter between 50 and 1 000 mm, iii) Diameter ratio between 0.316 and 0.8, and iv) Pressure ratio greater than 0.75.2) Long radius nozzlesi) Upstream Reynolds number between 6×103 and 107, ii) Pipe diameter between 50 and 200 mm, iii) Diameter ratio between 0.2 and 0.8, and iv) Pressure ratio greater than 0.75.1.4 Individual calibrations should be made when the profile (see 7 and 8) and installation conditions (see 5.3) differ from this standard.