Convenient means to obtain a value (marsh seconds) related to the mud viscosity. This value is obtained by adding one LITER of mud to the marsh funnel, and then measuring the time, in seconds, required to drain one quart from the funnel. The logic of this is that the only specialized piece of equipment required is the marsh funnel. You can always find a quart milk bottle on a drilling rig. This method will alert you when the mud changes the flow properties, but there is no mathematical relation between marsh seconds and the plastic viscosity of the mud.
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