fall ball viscometer experiment

1. To Determine The Viscosity of Fluid
Using Fall Ball Viscometer
(Find The Viscosity of SAE-30 Lubrication Oil)

2. Theory Background
Viscometer:
 A viscometer (also called viscometer) is an instrument used to measure the viscosity of a fluid.
 It is used for those fluids whose viscosity does not change under varying flow conditions.
 Rheometers must be used when the viscosity does change with flow conditions.
 Viscometers usually work by comparing a stationary object and a fluid flow, or vice versa. Hence, a
viscometer could be placed in a fluid flow or moved through a stationary fluid.
 The flow must have a Reynolds number in the laminar region in order to record accurate values.
The measure of the resistance is taken by measuring the drag resistance during relative motion
through the fluid.

3. Theory
• It consist of vertical long tube
which contains fluid whose
viscosity is to wanted and a
spherical metallic ball whose
density is known
• Measurement is done when ball
terminal velocity is achieved
• More will be viscous fluid more
will be the duration required
for ball to reach between two
points

4. Calculations and Formulas
 Measurement is done if we will find the unknown parameters in formula from
experiment
N =
2𝑔𝑎
2 𝜌−𝜌𝑠
9𝑣
Where:
g=value of gravity 𝜌𝑠=density of oil/water at room temp
a=Radius of bead/ball v=v1+
2.4𝑉1𝑎
𝑅
V=Terminal Velocity v1=linear velocity
𝜌=density of metallic ball R=Inner Radius of Pipe

5. Procedure and Measurements
 Fill glass tube with water or oil whose viscosity we wanted
to find
 Close the bottom valves and measure the inner dia of the
pipe
 Mark two points on tube and drop the ball note that the time
between two points and calculate linear velocity i.e s=v/t
use this velocity to calculate terminal velocity
 Then find dia of the ball,density of fluid and measure
absolute viscosity by putting unknown measured parameters
in equation
 Similarly replace the fluid and find its viscosity

6. ‘a’ Radius
of ball
‘R’ Inner
radius of
jar
‘t’ time
between
two points
‘s’
Distance
b/w two
points
‘v’ linear
velocity
‘v1’
terminal
velocity
‘N
viscosity