ISO INTERNATIONAL STANDARD 7884-2 First edition 1987-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION ME)KAYHAPOAHAA OPrAHM3AMA NO CTAHAAPTM3AWM Glass --- Viscosity and viscometric fixed points - Part 2 : Determination of viscosity by rotation viscometers Reference number ISO 7884-2 : 1987 (E) 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 the right to be represented on that committee. International organizations, govern- mental and non-governmental,in liaison withIsO,also takepart in thework. Draft International Standards adopted by the technical committees are circuiated to the member bodies for approval before their acceptance as International Standards by the ISo Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. InternationalStandardISO7884-2waspreparedbyTechnicalCommitteeISO/TC48, Laboratory glassware and related apparatus. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. ? InternationalOrganizationforStandardization,1987 Printed in Switzerland INTERNATIONAL STANDARD ISO 7884-2 : 1987 (E) Glass --- Viscosity and viscometric fixed points ： Part 2 : Determination of viscosity by rotation viscometers 0 Introduction ture range from about 1 600 to 600 c, the torque necessary ranging from 0,1 to 20 N-mm according to the construction of International Standard ISo 7884, Glass Viscosity and the apparatus. The method is applicabie if the rotational fre- viscometric fixed points, consists of the following separate quency does not exceed 8 s -1; however, at rotational frequen- parts : cies above 1 s-1it should be ascertained that inertia forces are negligible. Part 1: Principles for determining viscosity and viscometric fixed points. Reference Part 2: Determination of viscosity by rotation viscometers. IEC Publication 584-1, Thermocouples -- Part1:Reference Part 3: Determination of viscosity by fibre elongation tables. viscometer. Part 4: Determination of viscosity by beam bending. 3 Definitions Part 5: Determination of working point by sinking bar For the purposes of this part of ISO 7884, the following defini- tions apply. viscometer. Part 6: Determination of softening point. 3.1 Field of flow, crucible and plunger Part 7: Determination of annealing point and strain point by 3.1.1 field of flow : The whole gap fitled by the molten glass beambending. sample and the spatial distribution of the flow velocities within it, including its boundaries. Part8: Determination of (dilatometric) transformation temperature. 3.1.2 crucible: The outer boundary of the molten gtass sam- ple corresponding to the inner surface of the crucible up to the level of the melt. 1 Scope and field of application 3.1.3 plunger : The inner boundary of the molten glass sam- This part of Iso 7884 specifies a method of determining, by ple corresponding to the outer surface of the plunger up to the means of rotation viscometers, the dynamic viscosity of glass level of the melt. and, in particular, the viscosity-temperature relationship at any temperature or viscosity within the range of measurement. This 3.2 Flow field coefficient and instrument constant covers the ranges of viscosity for melting, refining and working of glass. 3.2.1 Rotation viscometers are either of the Searle type or of the Couette type, both of which allow the determination of the Thismethodallowsfor continuousmeasurements andfor viscosity according to basic equation (1): measurements under various shearing stresses (i.e. for the determinationofflow curves)in orderto check whether ornot the glass behaves as a Ne