BS U-Tube Viscometers for Transparent Liquids
BS U-tube capillary viscometers are designed for the determination of the kinematic viscosity of transparent liquids by measuring the flow time of the sample through a calibrated capillary at a controlled temperature.
They comply with BS, 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, solvents and, more generally, 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 U-tube configuration is specifically suitable for the measurement of transparent liquids, allowing direct observation of the meniscus as it passes the measuring marks and accurate determination of the flow time.
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: BS
- Application: transparent liquids
- 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, 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 available range includes Series A to H, with nominal constants from 0.003 to 10 and kinematic viscosity ranges approximately from 0.9 to 10,000 cSt.
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 the hot working of borosilicate glass, a material particularly well suited to laboratory applications due to its thermal and chemical resistance and its ability to withstand thermal shock. Shaping is carried out by localized flame heating, controlled rotation of the workpiece and air blowing, allowing precise geometries, uniform wall thicknesses and smooth connections with minimal internal stress.
The main processing techniques include blowing, drawing, constriction, expansion, glass-to-glass sealing, and the manufacture of standard ground joints, fittings, hose connections, stopcocks and special connections. Particular attention is paid to concentricity, wall-thickness uniformity and the continuity of sealed joints, all of which are essential to ensure 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 configurations.