# Rotational Viscometer / concentric cylinders

Rotational viscometers provide a great variety of measuring systems. For applications that require an exact definition of shear rate and shear stress, measuring systems according to ISO 3219 (1993, first issued in 1991) and DIN 53019 (draft 2004, first issued in 1980) are available. The basic idea of these standards is to postulate a limited dimension of the annular gap in order to achieve values of shear stress and shear rate which are as constant as possible in the entire shear gap.

As a rule, such standardized measuring systems are combined with some system for temperature control – depending on the model, they have either adapters for liquid baths or (thermo-)electric systems. The defined cylinder geometry reduces the required sample quantity and limits the viscosity measuring range in comparison to undefined measurement geometries. The listed specifications apply to a typical instrument with spring mechanics and a standardized concentric cylinder system.

## Physics

• Measured quantity: Torque
• Calculated quantity: Dynamic viscosity

## Performance

Rotational viscometers cover a very wide measuring range. The use of concentric cylinder measuring systems with a defined annular gap limits the measuring range.

• Viscosity measuring range - for a model for high shear/high torque measurements: 1 mPa.s to 109 mPa.s
• Measuring accuracy: > 3 %
• Temperature measuring range: -20°C (-16°F) to 180°C (356°F)

## Temperature control

Most concentric cylinder systems use a liquid thermostat for temperature control, but there are also systems available that provide (thermo-)electric heating and cooling.

## Sample

• Typical sample volume: 1 to 90 mL, depending on the system used
• Suitable for transparent and opaque samples

## Standards and Norms

DIN 1342, DIN 53019, EN/ISO 3219, DIN 54453 (double gap systems), USP <912>

## Overview

 Viscometer type Rotational Viscometer / concentric cylinders Rotational Viscometer Concentric cylinder systems model for high shear/high torque measurements torque dynamic viscosity 1 mPa.s 109 mPa.s -20°C 180°C yes yes no 1 to 90 mL --- --- < 3 % yes yes < 0.25 m² DIN 1342, DIN 53019, EN/ISO 3219, DIN 54453 (double gap systems), USP <912>

We offer typical values which are based on the values in brochures and standards but are not related to specific instruments.