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LACTOMETERBy
M. Anandavel
10m205
Lactometer:A Lactometer is a little glass instrument that
tests the purity of milk based on density/buoyancy.
It is used to find out the amount of water in the milk.
works on the principle of the specific gravity of milk.(Archimedes' principle)
Principle:Operation of the lactometer is based on
Archimedes' principle that a solid suspended in a fluid will be buoyed up by a force equal to the weight of the fluid displaced by the submerged part of the suspended solid.
Thus, the lower the density of the substance, the farther the hydrometer will sink.
Lactometer consists of a long cylinder stem connected to the
body, which is a large air chamber.
This chamber causes the instrument to float, attached to the
lower end of the body is the bulb which is filled with mercury
to cause the lactometer to sink up to the proper level and to
float in and up right position in the milk.
Inside the lactometer there may be a thermometer extending
from the bulb up into the upper part of the stem where the
scale is located.
This thermometer does not record temperature above
380C thus this liquid does not put into the milk above
this temperature.
Just below the thermometer is the lactometer scale,
with the graduation ranging from 15 at the top to 45 at
the bottom.
Each division is known as the lactometer degree.
The average reading of normal milk is 32.
Reading the lactometer:
In taking the lactometer reading of milk, sample of the
milk is thoroughly mixed, and pour the milk into a glass
measuring cylinder which is large enough to float the
lactometer freely.
Then the lactometer is inserted as soon as the
instrument comes to the rest ,read the division at the top
of the meniscus film and on a level with the milk.
The reading should be taken with a little delay as
possible, as the fat globules soon rise and there fore the
lower part of the lactometer would be resting in partially
skimmed milk.
Note the temp of the milk when reading the lactometer
and correct the lactometer degrees to standard temperature
How it sensesThe principle behind sensing the lactometer
reading is the specific gravity of the milk.It is based on its density or buyoncyThe mertcury contained bulb will float or sink
based on the density (creaminess) of the milk.
Calibration:The lower the
density of the fluid, the deeper the weighted float B will sink;
the depth can be read off the scale A
The scale is calibrated from top to bottom
Measuring the value:The values are measured in lactometer scale
in terms of lactometer degrees.The thermometer is also engaged to
measure the temperature of the milk in terms of degrees.
The scale at the top is the thermometer scale .(T)
The one at the bottom is the lactometer reading(L.R)
Measuring..Sample of milk taken and is poured into the
tube.Then the lactometer is inserted into the tube
with care.The correct lactometer reading is obtained
only at the temperature of 60C.If the temperatur e is not so then the reading
have to be corrected as per the following
Correcting the value:
Displaying the value:The lactometer scale displays the reading
and can be seen manually since it is a glass tube
Of course it might encounter some observation error.
The parallax and observation error have to be avoided while noting down the value.
Inferring:Higher the lactometer reading , higher will
be the density of the milk,(i.e.) low water content in that milk
Lower the lactometer reading , lower will be the density of the milk,(i.e.) high water content in that milk
THANK YOU..