ISO 7884-2:1987

Name: ISO 7884-2:1987 — Glass — Viscosity and viscometric fixed points — Part 2: Determination of viscosity by rotation viscometers
SKU: ISO 7884-2:1987
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Glass — Viscosity and viscometric fixed points — Part 2: Determination of viscosity by rotation viscometers

Название (английский):

ISO 7884-2:1987

Glass — Viscosity and viscometric fixed points — Part 2: Determination of viscosity by rotation viscometers

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 10
Дата публикации:: 26 ноября 1987 г.
Издание:: ISO IS 7884 edition 1 version 1
ICS:: 81.040.01

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Описание (английский):

This method allows continuous measurements viscosity and measurements under various shearing stresses. The viscosity is determined by the flow field coefficient, the torque and the rotational frequency. Two types of rotation viscometers are described: viscometer of the Couette type with adjustable revolving crucible and viscometer of Searle type with the crucibel at rest and the plunger revolving. The procedure is specified and typical examples of flow field with formules for calculating (annex A) and a typical rotation viscometer (annex B) are described.

Abstract

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Упомянутые в описании и другие стандарты ISO

Overview

ISO 7884-2:1987 defines a laboratory method for determining the dynamic viscosity of glass using rotation viscometers. It is Part 2 of the ISO 7884 series on glass viscosity and viscometric fixed points and covers continuous viscosity measurements and flow-curve (shear-rate) tests. Viscosity is obtained from the measured torque and rotational frequency together with a calculated or calibrated flow field coefficient and an instrument constant. The standard describes two rotation viscometer geometries (Couette and Searle) and includes practical annexes with flow-field formulae (Annex A) and an example viscometer (Annex B).

Key topics and technical requirements

Measurement principle: Viscosity determined from torque, rotational frequency and the flow-field coefficient or instrument constant; supports measurements at varying shear stresses to produce flow curves.

Viscometer types:

Couette type - revolving crucible, stationary plunger.
Searle type - crucible at rest, revolving plunger.

Calibration: Instruments must be calibrated with viscometric standard liquids or certified reference glasses (see ISO 7884-1) to determine instrument constant and correct for mechanical losses (friction, bearings, air drag).

Apparatus requirements:

Electrically heated tube furnace (normally up to 1 400 °C; special cases up to 1 600 °C).
Thermocouples (type S or B), calibrated and low thermal inertia.
Crucibles (ceramic or noble metal) with sample volumes typically 20–250 cm3.
Noble-metal plungers (platinum/rhodium alloys), shaft and torque-measuring device (torsion wire/spring/balance).
Devices for centring, concentricity checks (≤1/100 plunger diameter), and thermal stability.

Measurement control: Temperature stability to ±2 °C and gradient ≤1 °C/cm; rotational frequency typically ≤8 s−1 (inertia effects considered above 1 s−1); torque and frequency ranges chosen to give reliable instrument response.

Sample handling: Melted glass free of bubbles; careful loading and immersion to avoid contamination or foam; crucible protection recommended for fragile ceramics.

Applications and who uses it

Quality control and process laboratories in the glass industry (melting, refining, forming).

Research laboratories studying viscosity–temperature relationships and non‑Newtonian behavior of glass melts.

Instrument manufacturers and calibration labs for rotation viscometers.

Standardization bodies and testing services validating viscometric fixed points and certified reference glasses.

ISO 7884-2 is essential when accurate, reproducible rotational-viscometer measurements are required to characterize glass melt viscosity for production control, process modelling and material development.

ISO 7884-2:1987

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications and who uses it

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