march funnel
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. Other cones with different geometries and orifice arrangements are called flow cones, but have the same operating principle.
A modern plastic Marsh Funnel
In use, the funnel is held vertically with the end of the tube closed by a finger. The liquid to be measured is poured through the mesh to remove any particles which might block the tube. When the fluid level reaches the mesh, the amount inside is equal to the rated volume. To take the measurement, the finger is released as a stopclock is started, and the liquid is allowed to run into a measuring container. The time in seconds is recorded as a measure of the viscosity.
The Marsh Funnel[edit]
Based on a method published in 1931 by H.N.Marsh, a Marsh cone is a flow cone with an aspect ratio of 2:1 and a working volume of at least a litre. A Marsh funnel is a Marsh cone with a particular orifice and a working volume of 1.5 litres. It consists of a cone 6 inches (152 mm) across and 12 inches in height (305 mm) to the apex of which is fixed a tube 2 inches (50.8 mm) long and 3/16 inch (4.76 mm) internal diameter. A 10-mesh screen is fixed near the top across half the cone.
In American practice (and most of the oil industry) the volume collected is a quart. If water is used, the time should be 26 +/- 0.5 seconds. [1] If the time is less than this the tube is probably enlarged by erosion, if more it may be blocked or damaged, and the funnel should be replaced. In some companies, and Europe in particular, the volume collected is a litre, for which the water funnel time should be 28 seconds. Marsh himself collected 0.50 litre, for which the time was 18.5 seconds.[2]
The Marsh funnel time is often referred to as the Marsh funnel viscosity, and represented by the abbreviation
A modern plastic Marsh Funnel
In use, the funnel is held vertically with the end of the tube closed by a finger. The liquid to be measured is poured through the mesh to remove any particles which might block the tube. When the fluid level reaches the mesh, the amount inside is equal to the rated volume. To take the measurement, the finger is released as a stopclock is started, and the liquid is allowed to run into a measuring container. The time in seconds is recorded as a measure of the viscosity.
The Marsh Funnel[edit]
Based on a method published in 1931 by H.N.Marsh, a Marsh cone is a flow cone with an aspect ratio of 2:1 and a working volume of at least a litre. A Marsh funnel is a Marsh cone with a particular orifice and a working volume of 1.5 litres. It consists of a cone 6 inches (152 mm) across and 12 inches in height (305 mm) to the apex of which is fixed a tube 2 inches (50.8 mm) long and 3/16 inch (4.76 mm) internal diameter. A 10-mesh screen is fixed near the top across half the cone.
In American practice (and most of the oil industry) the volume collected is a quart. If water is used, the time should be 26 +/- 0.5 seconds. [1] If the time is less than this the tube is probably enlarged by erosion, if more it may be blocked or damaged, and the funnel should be replaced. In some companies, and Europe in particular, the volume collected is a litre, for which the water funnel time should be 28 seconds. Marsh himself collected 0.50 litre, for which the time was 18.5 seconds.[2]
The Marsh funnel time is often referred to as the Marsh funnel viscosity, and represented by the abbreviation
References: edit] Jump up ^ 13B-1 Recommended Standard Procedure for Field Testing Water-Based Drilling Fluids, Dallas: American Petroleum Institute, 1990 Jump up ^ H. N. Marsh (1931)Trans AIME vol 92 pp 234-251 "Properties and Treatment of Rotary Mud" Jump up ^ A. W. McCray & F. W. Cole (1979) Oil Well Drilling Technology University of Oklahoma Press ISBN 0-8061-0423-6 ^ Jump up to: a b M. J. Pitt (2000) SPE Drilling and Completion vol 15 no1 pages 3-6 “The Marsh Funnel and Drilling Fluid Viscosity: A New Equation for Field Use” Jump up ^ BS EN445:1997 Grout for prestressing tendons - test methods, British Standards Institute, 1997 Jump up ^ ASTM C939-10 Standard Test Method for Flow of Grout, ASTM International, 2010 ASTM D6910-04 Standard Test Method for Marsh Funnel Viscosity of Clay Construction Slurries N. Roussel & R. Le Roy (2005) Cement and Concrete Research vol 35 823-830 “The Marsh Cone: a test or a rheological apparatus?”