INTERNATIONAL STANDARD ISO 14511 First edition 2001-10-15 Measurement of fluid flow in closed conduits Thermal mass flowmeters Mesure de débit des fluides dans les conduites fermées Débitmètres massiques par effet thermique Reference number ISO 14511:2001(E) ISO 2001
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Contents Page Foreword...iv Introduction...v 1 Scope...1 2 Normative references...1 3 Terms and definitions...1 3.1 General terms...1 3.2 Specific terms...2 4 Selection of thermal mass flowmeters...4 5 Capillary thermal mass flowmeter (CTMF meter)...5 5.1 Principles of measurement...5 5.2 Typical design...7 5.3 Applications and limitations of use...8 5.4 Meter selection...10 5.5 Installation and commissioning...12 6 Insertion and/or in-line thermal mass flowmeter (ITMF meter)...13 6.1 Principles of measurement...13 6.2 Typical design...16 6.3 Applications and limitations of use...18 6.4 Meter selection...20 6.5 Installation and commissioning...22 7 Instrument specification sheet and marking...24 7.1 User specification sheet...24 7.2 Manufacturer's data sheet...24 7.3 Marking...25 8 Calibration...27 8.1 General considerations...27 8.2 Use of the desired gas under process conditions...27 8.3 Use of a surrogate gas...27 8.4 In-situ calibration...27 8.5 Insertion-ITMF meter...27 8.6 Calibration frequency...28 8.7 Calibration certificate...28 9 Pre-installation inspection and testing...29 10 Maintenance...29 10.1 General...29 10.2 Visual inspection...29 10.3 Functional test...30 10.4 Record keeping (maintenance audit trail)...30 Bibliography...31 ISO 2001 All rights reserved iii
Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 14511 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits, Subcommittee SC 5, Velocity and mass methods. iv ISO 2001 All rights reserved
Introduction This International Standard has been prepared to guide those concerned with the specification, testing, inspection, installation, operation and calibration of thermal mass gas flowmeters. A list of standards related to ISO 14511 is given in the bibliography. ISO 2001 All rights reserved v
INTERNATIONAL STANDARD ISO 14511:2001(E) Measurement of fluid flow in closed conduits Thermal mass flowmeters 1 Scope This International Standard gives guidelines for the specification, testing, inspection, installation, operation and calibration of thermal mass gas flowmeters for the metering of gases and gas mixtures. It is not applicable to measuring liquid mass flowrates using thermal mass flowmeters. This International Standard is not applicable to hot wire and other hot film anemometers, also used in making point velocity measurements. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard 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. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 4006, Measurement of fluid flow in closed conduits Vocabulary and symbols ISO 7066-2, Assessment of uncertainty in the calibration and use of flow measurement devices Part 2: Nonlinear calibration relationships Guide to the expression of uncertainty in measurement (GUM). BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML, 1st edition, corrected and reprinted in 1995 IEC 61000-4, Electromagnetic compatibility (EMC) Part 4: Testing and measurement techniques 3 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 4006 and the following apply. NOTE The term gas is used as a synonym for single gases, gas mixtures and vapours. 3.1 General terms 3.1.1 flowrate quotient of the quantity of fluid passing through the cross-section of a conduit and the time taken for this quantity to pass through this section NOTE In this International Standard, the term flowrate is used as a synonym for mass flowrate, unless otherwise stated. ISO 2001 All rights reserved 1