This document is a preview generated by EVS

Väljavõte

1 EESTI STANDARD EVS-EN ISO :1999 VOOLAVA KESKKONNA VOOLUHULGA MÕÕTMINE RÕHULANGU MÕÕTVATE MÕÕTERIISTADE ABIL. OSA 1: MÕÕTEDIAFRAGMAD, DÜÜSID JA VENTURI TORUD, MIS ON PAIGALDATUD ÜMMARGUSE RISTLÕIKEGA TORUSTIKESSE, MIS KOGU TORU ULATUSES ON VOOLAVA KESKKONNAGA TÄIDETUD Measurement of fluid flow by means of pressure differential devices - Part 1: Orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full

2 EVS-EN ISO :1999 EESTI STANDARDI EESSÕNA NATIONAL FOREWORD See Eesti standard EVS-EN ISO :1999 sisaldab Euroopa standardi EN ISO : A1:1998 ingliskeelset teksti. This Estonian standard EVS-EN ISO :1999 consists of the English text of the European standard EN ISO : A1:1998. Standard on jõustunud sellekohase teate avaldamisega EVS Teatajas. Euroopa standardimisorganisatsioonid on teinud Euroopa standardi rahvuslikele liikmetele kättesaadavaks Standard on kättesaadav Eesti Standardikeskusest. This standard has been endorsed with a notification published in the official bulletin of the Estonian Centre for Standardisation. Date of Availability of the European standard is The standard is available from the Estonian Centre for Standardisation. Tagasisidet standardi sisu kohta on võimalik edastada, kasutades EVS-i veebilehel asuvat tagasiside vormi või saates e-kirja meiliaadressile standardiosakond@evs.ee. ICS Standardite reprodutseerimise ja levitamise õigus kuulub Eesti Standardikeskusele Andmete paljundamine, taastekitamine, kopeerimine, salvestamine elektroonsesse süsteemi või edastamine ükskõik millises vormis või millisel teel ilma Eesti Standardikeskuse kirjaliku loata on keelatud. Kui Teil on küsimusi standardite autorikaitse kohta, võtke palun ühendust Eesti Standardikeskusega: Aru 10, Tallinn, Eesti; koduleht telefon ; e-post info@evs.ee The right to reproduce and distribute standards belongs to the Estonian Centre for Standardisation No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, without a written permission from the Estonian Centre for Standardisation. If you have any questions about copyright, please contact Estonian Centre for Standardisation: Aru 10, Tallinn, Estonia; homepage phone ; info@evs.ee

3

4 EVS-EN ISO :1999

5 EVS-EN ISO :1999

6 IS0 EVS-EN 51674:1991(E) ISO :1999 Contents Page 1 Scope Normative references Definitions Symbols and subscripts * Symbols * Subscripts Principle of the method of measurement and computation Principle of the method of measurement Method of determination of the diameter ratio of the selected standard primary device Computation of rate of flow Determination of density General requirements for the measurements Primary device Nature of the fluid Flow conditions Installation requirements General Minimum upstream and downstream straight lengths required for installation between various fittings and the primary device Flow conditioners General requirements for flow conditions at the primary device Additional specific installation requirements for orifice plates, nozzles and Venturi nozzles Additional specific installation requirements for classical Venturi tubes * Orifice plates * IS All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-1211 Gent&e 20 l Switzerland Printed in Switzerland ii

7 EVS-EN IS0 ISO 51674:1991(E) : Description Pressure tappings Coefficients and corresponding uncertainties of orifice plates Pressure loss, AQ Nozzles ISA 1932 nozzle Long radius nozzles Venturi tubes,...,...,..., Classical Venturi tubes Venturi nozzle,...,,...,.., Uncertainties on the measurement of flow-rate Definition of uncertainty Practical computation of the uncertainty Annexes A Tables of discharge coefficients and expansibility [expansion] factors ~ B Classical Venturi tubes used outside the scope of this part of IS C Pressure loss in a classical Venturi tube D Iterative computations., E Examples of values of the pipe wall uniform equivalent roughness, k III

8 INTERNATIONAL STANDARD EVS-EN IS0 ISO 5167=1:1991(E) :1999 Measurement of fluid flow by means of pressure differential devices - Part 1: Orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full 1 Scope This part of IS specifies the geometry and method of use (installation and operating conditions) of orifice plates, nozzles and Venturi tubes when they are inserted in a conduit running full to determine the flow-rate of the fluid flowing in the conduit. It also gives necessary information for calculating the flow-rate and its associated uncertainty. It applies only to pressure differential devices in which the flow remains subsonic throughout the measuring section and is steady or varies only slowly with time and where the fluid can be considered as single-phase. In addition, each of these devices can only be used within specified limits of pipe size and Reynolds number. Thus this part of IS cannot be used for pipe sizes less than 50 mm or more than mm or for pipe Reynolds numbers below It deals with devices for which direct calibration experiments have been made, sufficient in number, spread and quality to enable coherent systems of application to be based on their results and coefficients to be given with certain predictable limits of uncertainty. The devices introduced into the pipe are called primary devices. The term primary device also includes the pressure tappings. All other instruments or devices required for the measurement are known as secondary devices. This part of IS covers primary devices; secondary device@) will be mentioned only occasionally. 1) See IS0 2186:1973, Fluid flow in closed conduits secondary elements. - Connections for pressure signal transmissions between primary and 1