Direct-reading viscometer:

Commonly called a “v-g meter.” the instrument is a rotational-type device powered by means of an electric motor or handcrank, and is used to determine the apparent viscosity, plastic viscosity, yield point, and gel strengths (all of which see) of drilling fluids.

The usual speeds are 600 and 300 revolutions per minute.

See api rp13b for operational procedures.

Also see direct-indicating viscometer.