A rotameter is a variable area flow meter that measures fluid flow rate. It consists of a tapered glass or metal tube with a float inside that rises as flow rate increases. As fluid enters the bottom of the tapered tube, the float is pushed upward by drag force from the fluid until it reaches equilibrium where drag equals weight. The height of the float corresponds to flow rate and is read on an adjacent scale. Rotameters are simple, reliable, and provide a linear scale but must be mounted vertically and are susceptible to measurement uncertainty.

1. Construction and
working of Rotameter
P H A R M A C E U T I C A L E N G I N E E R I N G
D a t e - 1 0 t h o f O c t o b e r 2 0 1 9

2. Submitted To - Dr. Sheetu
Prepared By - Sammisla R Nayak
Registration Number- 11811217
Roll Number- 09
Section- Y1801

3. ROTAMETER

4. WHAT IS ROTAMETER ?
A rotameter is a device that
measures the volumetric flow
rate of fluid in a closed tube. It
belongs to a class of meters
called variable area meters,
which measure flow rate by
allowing the cross-sectional area
the fluid travels through to vary,
causing a measurable effect.

5. WORKING PRINCIPLE OF
ROTAMETERES
The rotameter's operation is
based on the variable
area principle: fluid flow raises a
float in a tapered tube,
increasing the area for passage
of the fluid. The greater the flow,
the higher the float is raised. The
height of the float is directly
proportional to the flowrate.

6. CONSTRUCTION OF ROTAMETER
• A rotameter is made up of a tapered tube
and a float inside it. The glass tapered tube
has a scale on the surface or a scale is placed
adjacent to it, according to purpose.
• Tapered tube : The tapered tube is placed
vertically in the flow channel with a conical
shape inside. The quantity measured is
defined by the height of float going up. Glass
tubes are used for both liquid and gas
measurement. Metallic tubes are used where
the process fluid with high temperature and
pressure.
• Float : Stainless steal floats are commonly
used, there are different types of metals from
lead to aluminium used as floats. A float
material, shapes are also varied according to
applications considering density. Spherical
shape floats are used for small flows.
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7. 7
• Fluid enters from the bottom of the tapered
tube, then some of the fluid strikes directly into
the float bottom and others pass aside the
float. Now the float experience two forces in
opposite direction, darg force upward and
gravitational force downward.
• Fluid flow moves the float upward against
gravity.At some point, the flowing area reaches
a point where the pressure-induced force on
the floating body exactly matches the weight
of the float. The float will find equilibrium when
the area around float generates enough drag
equal to weight - buoyancy.
• As the float weight and gravity are constant,
the distance float displaced upward is
proportional to the flow velocity of the fluid
passing through the tapered tube.
WORKING -

8. MEASURING PRINCIPLE OF VARIABLE AREA
FLOWMETRES -
• However,the difference
in this application is
that the value inside
the radicand is
constant since the
pressure difference will
remain constant and
the fluid density will
likely remain constant
as well. Thus, k will
change in proportion
to Q. The only variable
within k relevant to float
position is the flowing
area between the float
and the tube walls.
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9. 9
ADVANTAGES
• No external power
needed.
• Simple Reliable
Design.
• Can Measure Liquid or
Gas Flows.
• Scale is approximately
linear.
• It can measure flow
rates of corrosive fluid.
• Better rangeability.
• Low cost and low
pressure drop.
DISADVANTAGES
• It should be mounted
vertically.
• It requires lining
mounting.
• Uncertainty of the
measurement
• Difficult to handle the
glass type.

10. REFRENCES -
URL - https://en.wikipedia.org/wiki/Rotameter
Website Title - Wikipedia
Publication Day - 24
Publication Month - March
Publication Year - 2019
Access Day - 10
Access Month - October
Access Year - 2019
Article Title - Rotameter
URL - https://automationforum.in/t/working-of-rotameter-variable-
area-flowmeter/2978
Website Title - Industrial Automation, PLC Programming, scada &
Pid Control System
Publication Day - 15
Publication Month - January
Publication Year - 2018
Access Day - 10
Access Month - October
Access Year - 2019
Article Title - Working of Rotameter / Variable area flowmeter
URL - https://in.omega.com/prodinfo/rotameters.html
Website Title - Omega Engineering
Access Day - 10
Access Month - October
Access Year - 2019
Article Title - Rotameters
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11. THANK YOU