Marsh Funnel Viscometer
Description
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 946 ml of fluid to flow from a full Marsh Funnel.
Application
Marsh Funnel readings are qualitative measurements.
Frequent reporting of Marsh Funnel viscosity will show changes in fluid viscosity that could require corrective action.
Mud engineers depend on the Marsh Funnel to check the quality of drilling mud.
Equipment
• Marsh Funnel
• Measuring Cup (graduated)
• Stopwatch
• Thermometer
This instrument and the test procedure complies with ASTM Standard
06910/06910M- 09 Standard Test Method for Marsh Funnel Viscosity
of Clay Construction Slurries and API RP 138-1.
Features and Benefits
• Quick, on-the-spot measurements for periodically reporting mud consistency
• Simple, low-maintenance
• Transports easily for use in the lab, field, or on drilling rig
• Rugged, break-resistant plastic that holds shape with temperature changes
Fann No. 201 Marsh Funnel is a rugged, easy to operate instrument for rapid, on the spot measurements of drilling mud viscosity.
The rate of gelation and the density of the slurry considerably influence the viscosity measurement.
Frequent reporting of the funnel viscosity makes it possible for mud engineers to observe sudden changes in the slurry viscosity and to take corrective action when necessary.
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. (The screen will filter out the larger particles that could clog the outlet tube.)
When the funnel is filled to the proper level, it holds more than one quart of slurry.
3. Quickly remove your finger from the outlet tube, and at the same time, begin timing the slurry outflow.
4. Allow one quart (946 ml) of slurry to flow from the Marsh funnel into a measuring container.
5. Record the seconds it takes for the quart of slurry to flow from the funnel.
Report this value as the Marsh funnel viscosity. Also record the temperature of the slurry sample.
Calibration Instructions
Marsh Funnel calibration is easily checked by measuring the viscosity of fresh water.
The funnel is dimensioned so that the outflow of 946 ml of fresh water at 21 ± 3°C is 26 ± 0.5 seconds.
If the funnel is out of calibration,clean it again using a pipe cleaner, making sure that nothing is blocking the outlet.
If the funnel continues to give an incorrect reading for fresh water after cleaning, then replace the funnel.
