Rotameter in Fluid Mechanics. Rotameter, Variable Area Meter. Rotameter Construction. Working Principle of Rotameter. Apparatus Description. Formula for calculations. Lab observations and Calculations. Advantages and Disadvantages of Rotameter. Precautions.

1. ROTAMETER
PREPARED BY:
Fahad Ali
Maliha Mehar Qambrani
Muhammad Luqman Akbar
Javeria Tanveer
Hammad Azam
Lab Instructor:
Engr. Abdul Wakeel
Fluid Mechanics (Lab)
Civil Engineering
3rd Semester

2. ROTAMETER
As the area
changes there
will be a change
in volumetric
flow rate.
It measures flow
rate of liquid, gas
or light slurry.
Rotameter is a
variable area
flow meter used
to measure fluid
flow.

3. CONSTRUCTION

4. CONSTRUCTION
Float Tapered Glass Tube

5. TYPES OF FLOAT AND
TAPERED GLASS TUBE
• Tapered glass tubes
can be made of;
1. Glass
2. Metal
3. Plastic
• Floats also vary with
material and shapes.
• Their use vary with
the application.

6. WORKING PRINCIPLE
• It works on the principle of up-
thrust force (buoyant force) exerted
by fluid and force of gravity exerted
on fluid.
Three forces act on the float;
1. Buoyancy (A)
2. Weight (G)
3. Flow force (S)

7. WORKING
CASE-1: When flow is high (high velocity measurement).
• In this case the float is pulled in upward direction.
• When this float or gravity pull will balance the push,
then float will be in equilibrium.
• Then we can get reading from the graduated scale
and the flow will get outside in regular way.
CASE-2 : When flow is slow (low velocity measurement).
• The float will go in downward direction.
• The force of gravity becomes more stronger than up-
thrust force.
• The float settles down and we can get the readings as
the same.

8. APPARATUS DESCRIPTION

9. APPARATUS DESCRIPTION

10. APPARATUS
DESCRIPTION

11. OBJECTIVE
The main objectives of this experiment is to obtain the coefficient of discharge
from experimental data by utilizing ROTAMETER.
APPARATUS
1. Rotameter
2. Hydraulic bench
3. Stopwatch

12. FORMULA
Actual discharge = 𝑸 𝒂𝒄𝒕 =
𝑽
𝒕
𝒎 𝟑
𝒔
Rotameter discharge = 𝑸 𝑹 =
𝑨×𝒉
𝒕
𝒎 𝟑
𝒔
𝑪 𝒅 =
𝑸 𝒂𝒄𝒕
𝑸 𝑹
Where
• 𝐶 𝑑= coefficient of discharge
• V= Volume of water in beaker
• t=time taken for the beaker to be filled

13. PROCEDURE
• Priming is done first for venting air from pipes.
• The inlet valve is opened slightly such that the discharge on
rotameter is noted.
• Discharge collected in the beaker in time ‘t’ is noted.
• The above procedure is noted by gradually increasing the flow and
observing the readings.
• The observations are tabulated and the coefficient of discharge of
rotameter is compared.

14. OBSERVATIONS AND CALCULATIONS
Sr. No.
Volume Time
Flowrate
Qact
Rotameter
QR
Coefficient
Of discharge Cd
L Min L/min L/min
1 10 0.5333 18.7512 20 0.9375
2 10 0.7000 14.2857 16 0.8928
3 10 0.9500 10.5263 12 0.8772

15. ADVANTAGES
• The cost of rotameter is low.
• It provides linear scale.
• It has good accuracy for low
and medium rates.
• The pressure loss is nearly
constant and small.
• Usability for corrosive fluids.
DISADVANTAGES
• When opaque fluid is used,
float may not be visible.
• It has not well in pulsating
services.
• Glass tube types subjected to
breakage.
• It must be installed in vertical
position only.

16. APPLICATIONS
• The rotameter is used in
proces industries.
• It is used for monitoring gas
and water flow in plants
and labs.
• It is used for monitoring
filtration loading.

17. PRECAUTIONS
1. Maintain a constant discharge for each reading.
2. The parallax error should be avoided while
taking readings.
3. Take readings of discharge accurately.
4. The time of discharge collected in the beaker
should be noted accurately.
5. Readings must be taken thrice to compare the
values and to take the average of readings.

18. THANK YOU FOR YOUR
ATTENTION!