ISO INTERNATIONAL STANDARD 7884-5 First edition 1987-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION so ORGANISATION INTERNATIONALE DE NORMALISATION MEKAYHAPOAHAROPIAHM3ALMAOCTAHAAPTM3ALWM As lerurt Dor sec Glass - Viscosity and viscometric fixed points : Part 5 : Determination of working point by sinking bar viscometer Referencenumbei ISO 7884-5 : 1987 (E) Copyright lnt No reproduction or networking permitted without license from IHS 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, govern- mental and non-governmental, in liaison with iso, aiso 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. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7884-5 was prepared by Technicat Committee ISO/TC 48, Laboratory glassware and related apparatus. Users should note that all International Standards undergo revision from timeto time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. @International Organization for Standardization,1987 Printed in Switzerland n for Standardizatior No reproduction or networking permitted without license from IHS Not for Resale ISO 7884-5 : 1987 (E) INTERNATIONAL STANDARD Glass - Viscosity and viscometric fixed points Part 5 : Determination of working point by sinking bar viscometer 0 Introduction 3 Reference International Standard ISo 7884, Glass Viscosityand IEC Publication 584-1, Thermocouples - Part 1: Reference viscometric fixed points, consists of the following separate tables. parts : 4 Definitions Part 1 : Principles for determining viscosity and viscometric fixed points. For the purposes of this part of Iso 7884, the following defini- Part 2 : Determination of viscosity by rotation viscometers. tions apply. Part 3: Determination of viscosity by fibre elongation 4.1 working point : Temperature at which the melt of usual viscometer. silicate glasses possesses an equilibrium viscosity of Part 4 : Determination of viscosity by beam bending. 104 dPa.s*. Part 5: Determination of working point by sinking bar 4.2 sinking bar temperature : Working point as deter- viscometer. mined by means of the sinking bar method. Part 6 : Determination of softening point. Part 7: Determination of annealing point and strain point by 4.3 sinking bar method : Simple procedure for determining rapidly the viscosity within a range of about 103,7 to 104,5 dPa.s beam bending. as explained in clause 5. Part8: Determinationof(dilatometric) transformation temperature. 5Principle 1 Scope A vertically positioned narrow metal rod (the bar) of diameter d is allowed to sink under a force F (its own weight) into the melt. This part of ISo 7884 specifies a method of determining the From the rate of sinking of the bar into the melt, the dynamic working point of glass by means of the sinking bar viscometer. viscosity n of the melt is calculated. Under the geometricat con- This method has been found useful for characterizing the low- ditions specified in 6.1 and 6.3, the deviations of this method viscosity range of glass working. This viscometric fixed point from equation (1)are small comparedwiththe experimental can be used in determining the viscosity-temperature relation- uncertainties as specified in 9.2. ship (see ISO 7884-1). ...(1) 2 Field of application where This method is applicable to all glasses of normal bulk- C is a constant; production compo