2. Awais Ahmad RP14-CE21
Rana Aown Haider RP14-CE63
Hassan Haider Zaidi RP14-PG15
Usman Ahmad Khan RP14-PG07
3.
4. Part 2
Pressure drop
Flow rate
Coefficient of discharge
Part 1
Introduction to variable area meters
Rotameter
Construction
Principle
Working
Part 3
Modifications
Advantages
Disadvantages
Part 4
Applications
6. In the Variable area flowmeters
“the drop rate in the pressure is
constant and the flowrate is a function
of area of constriction”.
Most commonly Known variable area
meter is known as “ROTAMETER”.
12. The pressure drop arises from the conversion of pressure energy to kinetic
energy and from frictional losses which are accounted for in the coefficient of
discharge.
The pressure difference over the float -∆𝑃, is given by:
−∆𝑃 =
𝑽 𝒇 𝝆 𝒇−𝝆 𝒈
𝑨 𝒇
This equation shows the pressure difference across the float is equal to its weight
in the fluid divided by its maximum cross sectional area.
13. Rotameter is considered as an orifice meter with the variable
aperture, thus the formula used for orifice with slight changes
can be used.
19. Low cost
Low Pressure drop
Rangeability is better
It is suitable for small flowrates
It also measures the flowrate of corrosive fluids
it is easily equipped with alarms and switches or any transmitting device
20. It is difficult to handle the glass tube type.
It must be mounted vertically.
It requires in line mounting.
Accuracy = ± 0.5 to 10%
It is limited to low temperatures.
Generally it is limited to small pipe services.
22. Control panels
Control in research laboratories
Measurement & control on machinery
Pilot plants
Water purification (Osmosis)
Control of gas burners
Flow control for industrial refrigeration
Chemical / pharmaceutical / cosmetic industry
Lab scale rotameter