engineering

Marsh funnel

Marsh funnel is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Marsh funnel rather than just read about it. In short: 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.

Key takeaways

Marsh funnel belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Marsh funnel to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Marsh funnel from memory before moving on to harder problems.

Reference excerpt

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. 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 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. 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. The Marsh funnel time is often referred to as the Marsh funnel viscosity, and represented by the abbreviation FV. The unit (seconds) is often omitted. Formally, the volume should also be stated. The (quart) Marsh funnel time for typical drilling muds is 34 to 50 seconds, though mud mixtures to cope with some geological conditions may have a time of 100 or more seconds. 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. μ = ρ (t - 25) where μ = effective viscosity in centipoise ρ = density in g/cm3t = quart funnel time in seconds 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−1.

Other Flow Cones The term Marsh cone is also used in the concrete and oil industries. European standard EN445 and American standard C939 for measuring the flow properties of cement grout mixtures specify a funnel similar to the Marsh cone. Some manufacturers supply devices which they call Marsh cones, with removable tubes with size ranges from 5 to 15 mm. These can be used for quality control by selecting a tube which gives a convenient time, say 30 to 60 seconds.

References

Further reading 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?”

Illustrations

Worked examples

Example 1 — a first encounter with Marsh funnel

Start with the simplest possible case. Write down what Marsh funnel claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Marsh funnel before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Marsh funnel ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Marsh funnel

In research: Marsh funnel appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Marsh funnel in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Marsh funnel is common in secondary-school and first-year university syllabi. It links to neighbouring topics Drilling fluid, Petroleum engineering, Viscosity, so understanding it makes those chapters shorter.
In everyday life: Look for Marsh funnel outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Marsh funnel in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Marsh funnel means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Marsh funnel out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Marsh funnel in simple terms?

Why does Marsh funnel matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Marsh funnel?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Marsh funnel.