Particle size analysis hydrometer and sedimentation

1. PARTICLE SIZE ANALYSIS:
SEDIMENTATION ANALYSIS,HYDROMETER
ANALYSIS
PRESENTED BY :

2. Sedimention analysis:
SEDIMENTATION ANALYSIS
 Application:-
Determination of the grain size distribution of the soil fraction finer than 75 μ in size
 principle:-
Stokes law : The velocities of of free fall of spherical, fine particles, through a liquid are
different for different sizes.

3.  According to Stokes’s Law, the terminal velocity ,v is given by
V ∝ D2
using v in terms of distance/time we get; relationship
between time and diameter.
D∝ 1/√t
therefore D∝√v

4. HYDROMETER ANALYSIS
FINE-GRAIN ANALYSIS
Hydrometer Method Pipette Method
10cc of soil suspension is collected
Indirectly calculated by reading
density of soil suspension

6. • Let AA is the surface at which Hydrometer
calculates the specific gravity of liquid
• BB is the free surface of liquid
HR
HR
As we insert Hydrometer into the graduated cylinder
AA and BB surface rise to AA’ and BB’ respectively

7. HR
HR = Effective Depth
H1 = Height of Hydrometer’s submerged neck
h = Height of Hydrometer’s Bulb
A = Cross-sectional area of jar
VH / A = Rise in B
VH / 2A = Rise in A
1

8.  A graph is plotted between the Hydrometer reading RH and the effective depth HR . This is
called calibration plot. Such a calibration plot would take care of the effect of immersion of
hydrometer.

12. References
1. IS : 2720 (Part-4) - 1985
2. Basic and Applied Solid Mechanics By Gopal Ranjan and A.S.R. Rao