ASTM U-Tube Viscometers
reverse flow BS/IP/RF, for opaque liquids
U-Tube Reverse-Flow BS/IP/RF Viscometers for Opaque Liquids
U-tube reverse-flow BS/IP/RF capillary viscometers are designed for the determination of the kinematic viscosity of opaque liquids by measuring the flow time of the sample through a calibrated capillary at a controlled temperature.
They comply with BS-IP-RF, UNE 400313, ASTM D445, ASTM D446 and ISO 3104-3105 standards.
They are particularly suitable for quality control and research laboratories, as well as for petrochemical applications, lubricants, oils, dark-colored products and, more generally, opaque or non-transparent samples for which kinematic viscosity must be determined over a wide range of values.
The operating principle is based on the flow of the sample through a calibrated capillary under the action of gravity. The reverse-flow configuration is specifically suited to the measurement of opaque liquids, allowing the flow time to be determined according to the geometry required for this type of viscometer.
Measurements are normally carried out using a thermostatic bath in order to maintain both the viscometer and the sample at the temperature specified by the test method. The measured flow time is multiplied by the nominal or calibration constant of the viscometer to obtain the kinematic viscosity value, expressed in mm²/s or centistokes (cSt).
Main features
- Type: U-tube capillary viscometer
- Configuration: reverse flow BS/IP/RF
- Application: opaque liquids and non-transparent samples
- Measured parameter: kinematic viscosity
- Measuring principle: gravity capillary flow
- Unit of measurement: mm²/s (cSt)
- Nominal constant referenced at 40 °C
- For use with a temperature-controlled thermostatic bath
- Compliance: BS-IP-RF, UNE 400313, ASTM D445, ASTM D446, ISO 3104-3105
- Available in different Series, nominal constants and viscosity ranges
The Series identifies the capillary configuration and the corresponding measurable viscosity range. Series with lower nominal constants are intended for lower-viscosity samples, while increasing the constant progressively extends the measuring range to liquids with higher viscosity.
The availability of different configurations therefore allows the most suitable viscometer to be selected according to the sample characteristics, the expected viscosity and the conditions specified by the test method.
Scientific blown glassware is manufactured through hot working of borosilicate glass, a material particularly suited to laboratory applications due to its high thermal and chemical resistance and excellent resistance to thermal shock. Shaping is carried out by localized flame heating, controlled rotation of the glass, and air blowing to obtain precise geometries, uniform wall thickness, and smooth transitions with minimal internal stress.
The main processing techniques include blowing, drawing, constriction, expansion, glass-to-glass sealing, and the manufacture of standard ground joints, connectors, hose connections, stopcocks, and special fittings. Particular attention is paid to concentricity, wall thickness uniformity, and the continuity of welded joints, all of which are essential for reliable performance during heating, vacuum operation, and fluid transfer.
After forming, the glassware undergoes controlled annealing to reduce internal stresses generated during hot working. This process improves mechanical stability and resistance to thermal shock, making the glassware suitable for both standard laboratory applications and custom-designed experimental systems.