A3.1 General
A3.1.1 The reverse-flow viscometers for transparent and
opaque liquids include the Zeitfuchs cross-arm, Cannon-
Fenske opaque, BS/IP/RF and Lantz-Zeitfuchs viscometers.
Unlike the modified Ostwald and suspended-level viscometers,
the sample of liquid flows into a timing bulb not previously
wetted by sample, thus allowing the timing of liquids whose
thin films are opaque. Reverse-flow viscometers are used for
the measurement of kinematic viscosities of opaque and
transparent liquids up to 300 000 mm 2/s.