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..