Flow of Fluids: Types of Manometers

Flow of Fluids

The flow of a fluid occurs when several unbalanced forces act on the fluid. It is primarily a branch of fluid mechanics, and fluid flow is concerned with the fluid's dynamics. The fluid's motion continues until other unbalanced forces are added to it.

For example, while emptying a water bottle into a mug, the flow or velocity of the water is very high above the cup's lip and very low towards the bottom half of the mug. Gravity is the imbalanced force here, and the flow of water continues until the cup is tilted and the water is in the mug.

Types of Manometers

Following are various types of manometers

Small manometer

Manometers such as these operate on the principle of inclined tubes. A small manometer measures pressure variations or pressure changes of a very small magnitude.

Simple manometer

Manometers are at their most basic elements a glass tube that has a pressure gauge attached to one end and is open to the outside world at the other end.

There are four types of basic manometers:

Piezometer

Tubes are connected to the walls of vessels or pipes that contain liquid for the purpose of measuring its pressure. Calculate the height at which the liquid rises to obtain the gauge pressure of the liquid using p = ρ gh.


A piezometer tube must be at least 1/2 inch in diameter to avoid capillary forces. If the opening of the instrument is not parallel to any fluid flow, an inaccurate reading will result.

U-tube manometer

It is made from a glass tube bent into a V shape, with one end attached to the point of measurement and the other exposed to the atmosphere, as shown in the picture.

If the tube contains mercury, or any other liquid with a density significantly higher than that of the liquid whose pressure is being measured, then the tube contains mercury or any other liquid or fluid.

• For vacuum pressure
• For gauge pressure

Single column manometer

Micromanometers are connected to a well-pressurized pipe with liquid at high pressure. Pressure in the pipe will force the lighter liquid in the basin to push the heavier one downward.


The decline of a heavy liquid level will be quite little due to the bigger size of the basin. A large increase in heavy liquid in the right leg will result from this downward migration of heavy liquid into the basin.

Inclined tube manometer

Micromanometers with inclined tubes, such as the one shown in the figure, are designated as inclined tube micromanometers.



The slanted micromanometer has a higher sensitivity than the vertical tube type. Because of the slant, the heavier liquid moves a greater distance in the right limb. As a result, it might provide a greater reading for the given pressure.

Differential manometer

Differential manometers measure the difference between the pressures at two points in same or distinct piping systems.

A differential manometer is made out of a U-tube carrying a heavy liquid and two ends joined by pressure difference measuring points:

It has three further classifications -

Two piezometer manometer

It comprises of two piezometers installed at two distinct gauge sites to measure the pressure differential. The difference in liquid level between the two tubes may be used to calculate the pressure differential between the two places. It has certain constraints in the form of piezometers.

U-tube differential manometer

As shown in the picture, the point of measurement is attached to one end of a glass tube curved into a V while the other end is exposed to the atmosphere.


The two ends are linked to the two spots in the pipe where a pressure differential is necessary. Allow pressure at point A to be greater than pressure at point B. The higher pressure at A will then cause the heavier liquid in the U-tube to travel downward. Due to this effect, the heavy liquid in the right limb will ascend, causing the heavy liquid in the left limb to descend.

Inverted differential manometer

The U-tube of these manometers is inverted and filled with a light liquid. Both ends of the tube are connected to the locations where the pressure difference will be measured.

Low pressure is measured with it to distinguish between them. The diagram depicts an inverted U-tube with a differential manometer attached to points A and B. Assume that the pressure at point A exceeds the pressure at point B.

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