What is Marsh funnel viscometer?
The Marsh funnel is a simple device for measuring viscosity by observing the time it takes a known volume of liquid to flow from a cone through a short tube. It is standardized for use by mud engineers to check the quality of drilling mud. The time in seconds is recorded as a measure of the viscosity.
What is funnel viscosity?
Funnel viscosity is an indication of the overall viscosity of a drilling mud. With the aid of the measuring cup (viscosity cup) the time taken for one quart of water to pass through the funnel orifice tube should be 26 seconds.
What is the Marsh funnel viscosity of water?
The marsh Funnel viscosity represents the time in seconds that it takes a quart of ﬂuid (1500 mL) to ﬂow out of a cone via a short cylinder into a graduated cup. Marsh funnel viscosity is a direct indication of the overall viscosity of drilling mud. The standard Marsh funnel viscosity of water is approximately 26 s.
How is the viscosity of a Marsh funnel determined?
However the effective viscosity can be determined from following simple formula. For example, a mud of funnel time 40 seconds and density 1.1 g/cm³ has an effective viscosity of about 16.5 cP. For the range of times of typical muds above, the shear rate in the Marsh funnel is about 2000 −s.
Can a Marsh funnel be used as a rheometer?
While the most common use is for drilling muds, which are non-Newtonian fluids, the Marsh funnel is not a rheometer, because it only provides one measurement under one flow condition. However the effective viscosity can be determined from following simple formula.
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How do you clean a Marsh funnel viscometer?
Procedure The Marsh funnel should be clean and dry before performing this procedure. 1. Collect a fresh slurry sample. 2. Hold the funnel erect with a finger over the outlet tube, and pour the slurry into the funnel through the screen until the slurry level reaches the bottom of the screen.