Viscosity Standards and Reference Fluids Information
Viscosity standards and reference fluids assist in verifying or calibrating rheometers and viscometers. These substances establish traceability of the instruments to national and international standards. They provide certified values for parameters such as dynamic and kinematic viscosities, density, and measurement uncertainties.
Viscosity measurement quickly and accurately assesses the quality and efficiency of product performance. Standard activities include quality control, research and development, and flow characterization, information that is relevant at different stages of product design and manufacturing.
Reference fluids are prepared at laboratories based on master viscometer and rheometer scales calibrated to specific standards such as ISO 17025, AST D2162, and BS188. Calibrating the substances requires measuring them across a spectrum of temperatures. Reference fluids are replaced annually or biennially to ensure precision.
Viscosity or thickness parameters are important to many fluid dynamics applications. All liquids possess resistance to stress or shear, qualifying them as viscous. Rheometers are employed instead of viscometers when it is difficult to assign a single value to the substance. Such instances demand the analysis of further parameters. When performing the assessment, strict temperature control is necessary to avoid major variation in the readings.
The Value of Measuring Rheology and Viscosity
Measuring viscosity provides information for predicting the behavior of various materials, including the impact of formulation changes, processing, and aging. Rheological data is gathered when simple thickness properties are insufficient. It is effective in quality control checks by ensuring consistency of each batch of materials. Flow behavior analysis is an alternative means of evaluating a product's consistency and quality. Determining the rheological features of a fluid helps design pumping and piping mechanisms.
Such parameters are essential in polymer synthesis. They enable the discovery of relative differences without determining molecular weight. They facilitate monitoring chemical reactions as well. In addition, rheological properties serve as quality checks throughout production. They enable analysis of chemical, mechanical, and thermal activities, as well as additive effects.
Viscosity standards and reference fluids include:
General purpose silicone
General purpose oil
High-temperature silicone fluids
CAP oil fluids
R/S rheometer oil fluids
Krebs viscometer oil fluids
Categories of standards used in testing include:
Viscosity standards and reference fluids play a role in many processes, including manufacturing quality control (CQ), foof preparation, pipelines, polymer synthesis, and general chemistry.
Instruments that are subject to verification or calibration include:
Cone and plate viscometers
Rolling ball viscometers
Glass capillary viscometers
Cup and falling ball viscometers
Cold-cranking simulator viscometers (CCS)
ASTM D7042--Test methods for dynamic viscosity and density of liquids by Stabinger viscometer
ASTM D7483--Test methods for dynamic viscosity and derived kinematic viscosity by oscillating piston viscometer
ASTM D2162--Standards for calibrating master viscometers
ASTM D446--Specifications and instructions for glass capillary kinematic viscometers
ASTM D445--Test method for kinematic viscosity of transparent and opaque liquids
BS 188--Determining the viscosity of liquids
ISO/IEC 17025--Requirements for testing and calibrations labs
ISO 3104--Determining the kinematic viscosity and dynamic viscosity of transparent and opaque liquids
ISO 3105--Specifications and operation of glass capillary kinematic viscometers