1 Scope
This part of GB/T 2624 specifies the geometry and method of use (installation and operating conditions) of orifice plates when they are inserted in a conduit running full to determine the flowrate of the fluid flowing in the conduit.
This part of GB/T 2624 also provides background information for calculating the flowrate and is applicable in conjunction with the requirements given in GB/T 2624.1.
This part of GB/T 2624 is applicable to primary devices having an orifice plate used with flange pressure tappings, or with corner pressure tappings, or with D and D/2 pressure tappings. Other pressure tappings such as “vena contracta” and pipe tappings have been used with orifice plates but are not covered by this part of GB/T 2624. This part is applicable only to a flow which remains subsonic throughout the measuring section and where the fluid can be considered as single phase. It is not applicable to the measurement of pulsating flow. It does not cover the use of orifice plates in pipe sizes less than 50 mm or more than 1 000 mm, or for pipe Reynolds numbers below 5 000.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of GB/T 2624. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 2624.1-2006 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 1: General principles and requirements (ISO 5167-1:2003,IDT)
GB/T 17611-1998 Measurement of fluid flow in closed conduits-Vocabulary and symbols (idt ISO 4006:1991)
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in GB/T 17611-1998 and GB/T 2624.1-2006 apply.
4 Principles of the method of measurement and computation
The principle of the method of measurement is based on the installation of an orifice plate into a pipeline in which a fluid is running full. The presence of the orifice plate causes a static pressure difference between the upstream and downstream sides of the plate. The mass flowrate, qm, can be determined using Equation (1):
Foreword
1 Scope
2 Normative references
3 Terms, definitions and symbols
4 Principles of the method of measurement and computation
5 Orifice plates
6 Installation requirements
Annex A (informative) Tables of discharge coefficients and expansibility [expansion] factors
Annex B (informative) Flow conditioners
Bibliography
