ASTM D446 Specifications and Operating Instructions for Glass Capillary Kinematic Viscometers

Scope:

This standard applies to several commonly used viscometers that are acceptable for use with Test Method D445. Other glass capillary viscometers capable of detecting kinematic viscosity within the bounds of precision may also be utilized.

Procedure:

In ASTM D446 all viscometers are constructed from fully annealed, low-expansion borosilicate glass. Each viscometer has a permanent size number, serial number, and manufacturer’s designation. All timing marks are etched into the viscometer and filled with an opaque color or made permanent. All viscometers are designed to fit through a 51-mm hole in the lid of a constant-temperature bath with a liquid depth of at least 280 mm, with the liquid surface being no more than 45 mm from the top of the bath lid. The lengths of tubes and bulbs on the figures are kept within ±10 percent or ±10 mm, whichever is less, so that the viscometer’s calibration constant does not deviate from the nominal value by more than ±15 percent.

Specimen size:

As per ASTM D446, a 51-mm opening in the lid of a constant-temperature bath with a liquid depth of at least 280 mm is required for all viscometers.

Data:

Viscometer constant, C is calculated as:

C = ν/t

Where:

ν = the kinematic viscosity, mm² /s

t = the flow time, s

Conclusion:

ASTM D446 covers operating instructions for glass capillary kinematic viscometers i.e., Annex A1, Annex A2, and Annex A3.