Fann No. 201 Marsh Funnel Viscometer is a simple device for indicating viscosity on a routine basis. When used with a measuring cup, the funnel gives an empirical value for the consistency of a fluid. This number (time in seconds) depends on (1) the effective viscosity at the rate of shear prevailing in the orifice, and (2) the rate of gelation.
Funnel viscosity is the ratio of the speed of the sample as it passes through the outlet tube (shear rate) to the amount of force (fluid weight) that is causing the fluid to flow (shear stress).
Marsh Funnel viscosity is reported as the seconds required for one quart of fluid to flow from a full Marsh Funnel.