Definition(s)
Marsh Funnel Viscosity (or Funnel Viscosity)
Viscosity measured with the instrument used to monitor drilling fluid. NOTE A Marsh funnel is a tapered container with a fixed orifice at the bottom so that, when filled with 1 500 cm3 of fresh water, 946 cm3 (one quart) will drain in 26 s. It is used for comparison values only and not to diagnose drilling fluid problems. See ISO 10414-1 (API RP 13B-1) and ISO 10414-2 (API RP 13B-2).
Source: API RP 13C, Recommended Practice on Drilling Fluids Processing Systems Evaluation, Upstream Segment, Fourth Edition, December 2010. Global Standards