NTERNATIONAL STANDARD ISO) 2975/VII INTERNATIONAL ORGANIZATION FOR STANDARDIZATION -MEKAYHAPOAHA OPTAHW3ALIMA TIO CTAHJIAPTH3ALIMM·ORGANISATION INTERNATIONALE DE NORMALISATION Measurement of water flow in closed conduits -- Tracer methods - Part Vll : Transit time method using radioactive tracers Mesurededebitd'eaudans les conduites fermees-Methodespartraceurs- Partie Vll :Methodedutempsde transit,utilisant des traceursradioactifs First edition -1977-12-01 ISO 2975/VII-1977 (E) UDC532.574.87:621.039.85 Ref.No.ISO2975/VIl-1977 (E) Descriptors : flow measurement, pipe flow, water flow, tracer methods, radioactive isotopes, time measurement, position. Price based on 9.pages FOREWORD Iso (the International Organization for Standardization) is a worldwidefederation of national standards institutes (isO member bodies). The work of developing International Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up 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. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. International Standard ISO 2975/Vll was developed by Technical Committee ISO/TC 30,Measurement of fluid flow in closed conduits,and was circulated to the member bodies in September 1976. It has been approved by the member bodies of the following countries : Belgium India Romania Egypt, Arab Rep. of Korea, Rep. of Turkey Finland Mexico United Kingdom France Netherlands U.S.S.R. Germany Portugal Yugoslavia The member bodies of the following countries expressed disapproval of the docu- ment on technical grounds : Japan U.S.A. InternationalOrganizationforStandardization,1977 Printed in Switzerland ISO 2975/VII-1977 (E) INTERNATIONALSTANDARD Measurement of water flow in closed conduits Tracer methods Part Vll : Transit time method using radioactive tracers O INTRODUCTION where This International Standard is the seventh of a series of Visthe volumeof theconduitbetweenthedetector standards covering tracer methods of water flow measure- positions; ment in closed conduits. f is the transit time of the labelled fluid particles. The complete series of standards is as follows : In general, the theoretical condition for the validity of the - Part 1 : General. fusion": i.e. that the ratio of the local velocity to the Part Il : Constant rate injection method using non- longitudinal dispersion coefficient be equal at both ends of radioactive tracers. the measuring section. Part Ill:Constant rate einjection method using In practice this condition is fulfilled when the conduit has radioactive tracers. a constant cross-section. PartIV: Integration (sudden injection) method The value of t is obtained by measuring the difference in using non-radioactive tracers. abscissae of characteristic points (in theory:centre of PartV:Integration (sudden injection) method gravity, but in practice other characteristic points may be using radioactive tracers. found, see 5.6) of recorded distributions, corresponding to concentration/time distributions or their integrals, obtained Part VI : Transit time method using non-radioactive at each detection cross-section.The signal from the detec- tracers. tors shall be proportional to the tracer concentration. The value of the proportionality coefficient and hence the PartVll:Transit time method using radioactive absolute concentration value need not, however, be known tracers. exactly. 1SCOPEANDFIELDOFAPPLICATION This International Standard specifies the transit time method using radioactive tracers for the measurement of water flow 3 REQUIREDCONDITIONS rate in closed conduits. 3.1 Tracer 2 PRINCIPLE The tracer shall meet the general requirements defined in clause 5 of part I, when a