Working Principle of Vacuum Distillation

Vacuum Distillation works on the principle of simple distillation with few changes. According to this method, the desired liquid is distilled at a temperature lower than its boiling point by the application of vacuum.

When vacuum is applied, it means that the pressure above the liquid surface is lowered which enhances the rate of distillation. Liquid begins to boil when its vapour pressure is equal to the pressure above the system i.e., liquid surface.

Large-Scale (Industrial Scale) Apparatus :

Construction of Vacuum Distillation Small-scale (laboratory scale)

The small-scale (laboratory scale) apparatus consists of a two-necked flask condenser (known as Claisen flask), receiver, adapter and a vacuum pump. The liquid feed is boiled using a water bath or oil bath. A capillary tube is placed in one of the necks of Claisen flask. This tube prevents bumping and splashing of feed liquid. The tip of the tube should be dipped into the feed, so as to draw out the stream of air bubbles from the flask. A thermometer is inserted in the second neck of the Claisen flask. Claisen flask is connected to a condenser which in turn is connected to a receiver via an adapter.

The adapter has a provision for vacuum pump. A manometer (pressure gauge) is placed between the vacuum pump and the receiver so as to monitor the pressure change.

Working of Vacuum Distillation Small-scale (laboratory scale)

The liquid feed to be distilled is introduced into the Clause flask. Few porcelain pieces (glass beads) are added to the liquid feed to avoid bumping and splashing. Bumping is also minimized by the capillary tube that is inserted into one of the necks of the flask. The required vacuum is applied. The liquid feed is then boiled using a water bath or oil bath. The liquid feed boils when its vapour pressure becomes equal to the pressure above the system under the influence of vacuum.

The mixed vapours enter the condenser and gets condensed. They are then collected in the receiver. The temperature at which the liquid begins to boil is noted from the thermometer. This temperature is found to be lower than the boiling point of the liquid.

Large-Scale (Industrial Scale) Apparatus :

Construction of Vacuum Distillation Large-Scale (Industrial Scale) Apparatus

It is almost similar to apparatus used for simple distillation. The unit comprises the following essential parts,

1. Still

It consists of a large stainless steel or copper vessel, in which the liquid mixture to be distilled is placed. There is also a provision for thermometer. The hood of the still consists of an observation window to monitor the progress of the process. This observation window is also useful to see whether the liquid mixture to be distilled is at the right level or not. The hood also consists of a feed inlet. Steam is used as a heating medium which is circulated through the jacket. The base of the still is provided with a steam inlet and outlet.

2. Condenser

It is responsible for the condensation of vapours liberated from the still. It is made up of stainless steel and is covered with a jacket through which water is circulated in counter-current direction.

3. Receiver

Large scale distillation unit employs large metal containers made up of stainless steel. After condensation, the condensed vapours are carried into the receiver.

Working of Vacuum Distillation Large-Scale (Industrial Scale) Apparatus

The still is charged with the liquid mixture to be distilled, through a pipe from the reservoir for feed, at a controlled rate. Vacuum is applied by using a vacuum pump. Liquid mixture is heated with the aid of steam which is introduced into the jacket of the still. Under the influence of vacuum, the distillation temperature gets reduced and the liquid gets distilled at a temperature lower than its boiling point. The vapours are then fed to the condenser where they get condensed by the cool water circulating through the condenser jacket. The condensed vapours are then collected into the receiver.

Advantages of Vacuum Distillation

1. Application of vacuum reduces the distillation temperature to a greater extent. Hence, distillation occurs at a faster rate. As the distillation temperature is low, thermolabile substances can be distilled without any deterioration or decomposition of active constituents.

Disadvantages of Vacuum Distillation

1. Sudden application of vacuum to the hot boiling liquid may lead to foaming. However, excess foam formation can be avoided by the addition of anti- foaming agents such as capryl or octyl alcohol, silicones such as DC antifoam A etc.
2. Violent splashing of the liquid feed, may cause entrainment of feed molecules in the condenser. This can be avoided by inserting a thin capillary tube in one of the neck of the Claisen flask.
3. Vacuum distillation is not useful for the preparation of semi-solid or solid extract.

Applications of Vacuum Distillation

1. Substances which are susceptible to degradation at higher temperatures are termed thermolabile (heat-sensitive). The active constituents in a drug may deteriorate and become inactive, when they are subjected to extraction and concentration at higher temperatures. Hence, these substances are distilled by vacuum distillation.
2. The method can also be used to obtain granular and porous powders.

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Figure 1: Semi-Continuous Centrifuge.

Working Principle of Semi Continuous Centrifuge

Perforated semi-continuous centrifuge, also known as short cycle or automatic batch centrifuge works on the principle of filtration. The separation occurs through a filter medium (i.e., perforated wall) based on the difference in the densities of solid and liquid phases.

Construction of Semi Continuous Centrifuge

1. It consists of a vertical perforated basket which rotates on a horizontal axis (see Figure 1).
2. The slurry to be filtered is introduced from the feed tube.
3. Wash pipe (for washing the filter cake) is also introduced parallel to the feed pipe.
4. The feeder controls the thickness of the feed and automatically stops its supply.
5. When the discharge of crystals is desired, the hydraulic cylinder is attached in such a way that the discharge chute enters the basket from its sides.

Working of Semi Continuous Centrifuge

1. Feed is introduced in the basket through the feed tube.
2. The basket is allowed to rotate along the horizontal axis.
3. Due to the process of centrifugation, solids get retained in the filter in the basket and the filtrate leaves the basket from its outlet. The solid crystals are washed and the washed water is drained out which leaves from the outlet. The feeder maintains the feed thickness i.e., a thickness of 50-70 mm is preferred.
4. When the hydraulic cylinder is attached along with the discharge chute, the knife is lifted. It cuts the filter cake such that a layer of crystals is left back. This layer of crystals now sewed as a filter medium in the next cycle.
5. The feeder and the hydraulic cylinder makes the process semi-automatic, hence the name semi-automatic/semi- continuous centrifuge.
6. The crystals obtained contain 2-4

Advantages of Semi Continuous Centrifuge

1. Semi-continuous centrifuge is semi-automatic.

Disadvantages of Semi Continuous Centrifuge

1. Crystals may break while discharging.
2. Designing and operation of the centrifuge is complicated.
3. Increased labour requirement.
4. Higher power consumption.

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Figure 1: Super Centrifuge.

Working Principle of Super Centrifuge

It works on the principle of sedimentation. It enables the separation of two immiscible liquid based on the difference in their densities. Due to the centrifugal force, the heavier liquid is thrown against the wall, while the lighter liquid forms the inner layer (near centre).

Construction of Super Centrifuge

1. It consists of a hollow cylindrical bowl.
2. The diameter ranges from is 1.75 – 5 inches with a length of 9-30 inches.
3. It is attached to a flexible spindle at the top and to a loose-fit bushing at the bottom.
4. The bowl is mounted in such a way that it can be rotated on its longitudinal axis.
5. The liquid which is to be separated is introduced into the bowl under pressure through the feed inlet.
6. Two outlet provisions are made at different heights at the top of the centrifuge.
7. Modified weirs can be used for simultaneous recovery’ of the separated liquids.

Working of Super Centrifuge

1. Feed is admitted at the bottom of the centrifuge through a feed nozzle under vacuum system.
2. Power is supplied to the entire system to rotate it in vertical manner.
3. The speed of rotation is up to 2000 rpm.
4. By the centrifugation process, the heavier liquid phase is thrown out against the wall, while the lighter liquid settles as an inner layer.
5. Hydraulic balance maintains the liquid-liquid interface (neutral zone) between two immiscible liquids.
6. Separated liquid phases are collected from the top of the bowl through outlets with the help of modified weirs.
7. Simultaneous removal of two immiscible liquids is possible enabling continuous operation.

Advantages of Super Centrifuge

1. Efficiency of separation is high.

Disadvantages of Super Centrifuge

1. Output is limited.

Modifications of Super Centrifuge

Tubular bowl centrifuge

1. Used for the separation of solids and liquids when solid content is low.
2. From a suspension, the solids get accumulated on the wall, while the liquid can be clarified from the top by centrifugal force.
3. If necessary, the deposited solid is collected at regular intervals.
4. Limited capacity.

Applications of Super Centrifuge

1. These are widely employed in food, biochemical and pharmaceutical industry.
2. Used to separate phases of emulsions.
3. Clarification of liquid can also be carried out.

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Figure 1: Bag Filter.

Bag Filter equipment is not meant for actual size separation process. Instead, it is used as an auxiliary equipment with cyclone separator or air separator for the separation of fines and dust particles.

Working Principle of Bag Filter

Air-containing fines or dust particles obtained from the milled powder is forcefully introduced into the bag filters. These filters are made up of cotton or wool fabric. Air is introduced under the influence of suction applied on the opposite side of the feed inlet. This enables in the separation of particles. The particles stick to the walls of the bags. Air supply is cut off and the filters are shaken vigorously at high speed. As a result, dust particles adhering to the walls of the filters fall off and are collected from the conical base into a hopper.

Construction of Bag Filter

Bag filters consist of a number of cylindrical bags made up of cotton or wool fabric. These bags are suspended in a sheet of metal container which is tapered at the base. A hopper is placed by the side of the sheet metal container in continuation with the conical base of the container. On the top of the unit, a suction fan is present to maintain a pressure less than the atmospheric pressure. A bell crank lever arrangement is present which consists of a shaft operated by means of a cam. The cam presses the bell crank lever back and forth which in turn changes the position of the damper, which controls the motion of the bell crank lever. Hence, it aids in controlling two steps; filtering and shaking. A suction fan is present beside the damper. A hopper is present at the bottom of the filter to collect the dust particles.

Working of Bag Filter

The working of the bag filters involves the following two steps.

Filtering :

During this stage, air containing the dust particles is introduced into the bag filter through a hopper placed at the side of the sheet metal container. The air ascends into the filter bags under the influence of suction created by means of a suction fan present on top of the bag filters. This leads to reduction in pressure. The suction fan maintains the entire unit at a pressure lower than the atmospheric pressure. As the air laden with dust particles ascend dust particles remain inside the filter bags and the air passes upwards towards the top portion of the equipment. Due to the presence of air inside the bags, they remain completely stretched (taut) during the filtering stage. Drilling this period, the shaft with a cam is rotated at a very low speed. The cam does not press the bell crank lever. Due to this, the damper remains in place so that the filter bag comes in contact with the suction. As the feed inlet is closed, there is no contact between the filter bags and the atmosphere.

Shaking :

After few minutes, the shaft is rotated at a very high speed. The cam attached to the shaft presses the bell crank lever. Due to this, the damper changes its position and thus vacuum is cut off as there is no contact between the filter bags and suction. The feed inlet opens and the filter bags come in contact with the atmosphere. When dust laden air (considering the above condition) is introduced into the bag filters, it results in violent jerking of the bags. The dust panicles adhering to the walls of the filter bags fall into the conical base and are collected into a hopper (or chute) at regular intervals of time.

Advantages of Bag Filter

1. Fines generated during milling operation can be removed by bag filters, when other methods of separation cannot be employed.
2. The process is completely automatic, does not require manual labour.
3. The equipment can also be designed to promote very large filtering surface per unit floor space.

Applications of Bag Filter

1. Bag filters are used in association with other size separation equipment such as cyclone separator, air separator in order to remove dust or fines.
2. It can also be attached to a fluid energy mill discharge for the removal of fines.
3. Used to remove dust.

Example: Household vacuum cleaner works on the same principle.

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Working Principle of End Runner Mill

End Runner Mill works on the principle of compression and shearing stress offered to the feed by the heavy weight steel pestle. However, its use has become obsolete.

Construction of End Runner Mill

It is basically a mechanical mortar and pestle. The shallow mortar is made up of bed of stones or mild steel. The pestle has a flat bottom and is cylindrical and dumb bell shaped. The pestle is arranged eccentrically on the shallow mortar. The pestle carries a hinged arm so that it facilitates in emptying the feed and for cleaning the device just by raising the pestle. Inside the shallow mortar, a scrapper is arranged which brings the feed material towards the grinding surface.

Working of End Runner Mill

Feed material is introduced in the mortar and the motor is switched on. The mortar revolves, which leads to the rotation of the pestle. This rotation is due to the friction produced between the contacting surfaces of the mortar and the pestle. The scrapper brings the material towards the grinding zone. The material is size reduced by crushing and shearing phenomena. The product is collected and then sieved to obtain the desired particle size.

Advantages of End Runner Mill

1. It is a laboratory scale mill.

Disadvantages of End Runner Mill

1. Unbroken drugs or those in slightly broken conditions cannot be milled by end runner mill.

Applications of End Runner Mill

1. Brittle and crystalline feed materials are size reduced to fine powder.

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Figure 1: Hammer Mill.

Working Principle of Hammer Mill

Hammer mill works on the principle of impact for size reduction of materials. Impact is offered to the feed by the sets of swing hammers which are arranged on a rotor disk.

Construction of Hammer Mill

It consists of a casing in which a horizontal shaft is present (see Figure 1). A high speed rotor disk is attached to this horizontal shaft. A set of swing hammers are attached to the high speed rotor disk. Swinging action of the hammers is beneficial in avoiding the build-up of the material between the hammer and the screen.

Hammer mill may contain many rotor disks of diameter 150 to 450 min to which swing hammers of 4 to 8 in number are attached. The hammers are either straight with plain, enlarged or sharpened ends. A stationary anvil is arranged in the casing along its periphery. At the discharge site, a screen is present which sieves the product.

Working of Hammer Mill

Feed is introduced from the top of the mill. As the feed enters the grinding zone, it is size reduced by the swing hammers by beating. From here, the particles are further size reduced by the action of stationary anvil and by the rubbing action of hammer mill. The powder is screened and then discharged through the outlet. Several size of screens can be used depending upon the grade of fineness of the product desired.

Movement of hammer draws air into the mill, helps to nullify the heat generated during the process.

When the peripheral speed of hammer tips is 110 m/s, 0.1 to 15 tons of material is size reduced per hour to a size which passes through 200 mesh screen.

Advantages of Hammer Mill

1. Easy to install and easy to dismantle for cleaning.
2. Replaceable screen.
3. Dust produced during size reduction and explosion hazards may be prevented as the mill is closed.
4. A variety of feed can be size reduced which makes the hammer mill versatile.
5. It occupies less floor space.

Disadvantages of Hammer Mill

1. Only softer material can be size reduced to fines.
2. The screen possesses the risk of clogging.
3. Screen and the mill may get affected by abrasive feed material.
4. There are chances of production degradation as the heat generated during milling is high.
5. It is not suitable for fibrous, hard and sticky materials.

Applications of Hammer Mill

1. Non-abrasive to moderately abrasive materials are size reduced.
2. Cakes, slurries ointments filter press cakes can also be milled.

Modifications of Hammer Mill

1. Fitz mill/Fitz Patrick Comminuting machine – It is used for size reduction of the materials like herbs, glands, livers, roots etc.
2. Stoke Tornado Mill.

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Colloid mills can be sterilized and therefore can be used for size-reduction of sterile products.

Working Principle of Colloid Mill

Colloid mill works on the principle of high-velocity fluid shear due to the suspended particles or liquid droplets are milled, to form a uniform and stable suspension or emulsion respectively.

Construction of Colloid Mill

It consists of a cone-shaped rotor and a stator enclosed in a vessel (See Figure 1). Space between the rotor and stator can be adjusted up to 25 μ depending upon the particle size required. The rotor is rotated while the stator is kept stationary. Diameter of the rotor ranges from 6-15 inches. Small mills have low capacity i.e., about 30 to 50 gal/hr of the feed can be processed, while in large mills 7000 gal/hr of feed is processed. The rotor and stator are made up of invar alloy. This material expands to a very- less extent such that the grinding capacity of the mill is not changed due to the heat generated. The rotor is made wear resistant by lining it with silicon carbide. In most of cases, cooling water jacket is installed for reducing the heat generated during the process, “While in others a heating jacket is installed in case of formulation of an emulsion. At the top, a feed inlet is present. The outlet present at the bottom of one side of the vessel is connected to a hopper to recycle the discharge. The dispersion colloid mills are of 4 types; orifice device, hammer mill, smooth surface disk and rough surface disk.

Working of Colloid Mill

Pre-milled feed is added to the mill via the hopper and the motor is switched on. If the capacity of the mill is up to 1500 gal/hr, rotor is operated at 3600 rpm. This allows the feed to enter the clearance between the rotor and stator. Due to this, high velocity fluid shear is generated, which helps in size reduction. Clusters or liquid droplets are disrupted and the particles are dispersed uniformly. The product is received from the discharge which is 1 m or less in size. The heat generated during the process (40ºC) is reduced by circulating cold water in the jacket, which brings down the temperature to 20ºC. The discharge is recycled until the desired particle size is obtained.

Advantages of Colloid Mill

1. Ultrafine grinding upto the size of 1 μ or less is achieved.
2. Mill can be sterilized and hence sterile milling is achieved.

Disadvantages of Colloid Mill

1. During milling, air gets trapped in the product. This is removed by keeping the product aside to facilitate de-aeration.
2. Heat up to 40ºC is generated during the process, which has to be reduced by cooling water jacket.
3. Not suitable for dry milling.

Applications of Colloid Mill

1. Syrups and paints are processed.
2. Milk and purees are processed.
3. Ointments, suspensions, emulsions and colloidal dispersions are processed
4. Fibrous materials can also be processed by using rough surfaced rotor and stator.

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Simple Manometer

Simple manometer is most commonly used for measuring the pressure difference. It consists of U-shaped glass tube which is filled with liquid X and Y. X and Y are the two immiscible liquids the light shaded portion of the tube is filled with liquid X having a density ‘ρ_X‘. The arms of the tube above the liquid X i.e., the dark shaded portion is filled with liquid Y having density ‘ρ_y‘. The pressure exerted in left arm of the tube at point 1 is P₁ (pascals). Similarly, pressure P₂ is exerted in right arm of the tube at point 5.

According to fluid statics, the pressure at point 2 is given by the equation below.

1.    At point 2, the pressure is = P₁ + (h₁ + h₂)ρ_yg    ….(1)

Where, (h₁ + h₂) Distance from 3 to 5.

2.    At point 3, the pressure is = P₁ + (h₁ + h₂) ρ_yg    ….(2)

[2, 3 are at the same level]

3.    At point 4, the pressure is = P₂ + h₁ρ_yg    ….(3)

Equation (3) is written by considering the right arm of the tube.

The pressure at point 4 can also be “written by considering the left arm of the tube as follows,

At point 4, the pressure is = P₁ + ρ_Y (h₁ + h₂)g ρ_xh₂g    ….(4)

Equations (3) and (4) are equated because both the equations represent the pressure at point 4. Hence,

\[{{P}_{1}}+{{\rho }_{Y}}({{h}_{1}}+{{h}_{2}})g-{{\rho }_{X}}{{h}_{2}}g={{P}_{2}}+{{h}_{1}}{{\rho }_{y}}g\]

\[{{P}_{1}}-{{P}_{2}}={{h}_{1}}{{\rho }_{y}}g-{{\rho }_{Y}}({{h}_{1}}+{{h}_{2}})g+{{\rho }_{X}}{{h}_{2}}g\]

\[\Delta P={{h}_{1}}{{\rho }_{y}}g-{{h}_{1}}{{\rho }_{y}}g-{{h}_{2}}{{\rho }_{Y}}g+{{h}_{1}}{{\rho }_{y}}g\]

\[\Delta P={{h}_{2}}({{\rho }_{X}}-{{\rho }_{y}})g….(5)\]

It is concluded from equation (5) that,

1. The value of h₂ can be measured in metres i.e., h₂ is nothing but the difference in the levels of the liquid X in the two arms
2. The difference in the pressures (ΔP) is independent of the value of h₁ and the dimensions of the U-tube.

Mercury is used as a monomeric liquid (liquid X) in case of large pressure differences. Alcohol and carbon tetrachloride are used in case of small pressure differences.

Applications of Simple Manometer

1. Manometers are attached to the flow meters such as orifice and Venturi meters to measure the flow of fluids.
2. Pitot tube uses a manometer to measure the velocity head.
3. Consumption of gases in the chemical reactions can be measured using a simple manometer.

Differential Manometer

Differential manometer is used for the measurement of small pressure differences and also termed as two-fluid-U-tube manometer. It comprises two immiscible liquids i.e., liquid 1 and 2 of nearly equal densities. Enlarged chambers are constructed in such a way that the meniscus of liquid in the enlarged chambers does not appreciably change or remain unchanged with changes in the reading (h). By employing the same principle of simple manometer, the pressure difference (ΔP) is given by,

\[{{P}_{1}}-{{P}_{2}}=\Delta P=h({{\rho }_{3}}-{{\rho }_{1}})\]

The above equation indicates that for a given ΔP, the smaller the difference between the densities of liquid, the larger will be the reading on manometer.

Applications of Differential Manometer

1. These are useful for measuring minute differences in the pressure of the gases.
2. Due to the capillarity, they are free from errors and do not require calibration. Instead the micrometer scale is checked.

Inclined Manometer

Inclined manometer is used for measuring small pressure differences. It is essentially a modification of simple manometer, wherein one arm of the simple manometer is kept vertical while the other is inclined at an angle θ. The vertical arm has a large enlargement so that when the angle of inclination is changed, the meniscus in the enlargement does not allow any appreciable or measurable movement.

The angle of inclination is such that the fluid meniscus in the inclined arm should move a measurable distance for a small magnitude of R. The distance moved by the meniscus is given by R/sinθ. On making the angle of inclination further small. the fluid in the inclined arm moves through a longer distance (R’). This distance is multiplied by the magnitude of R. the value of which is equivalent to pressure difference.

Therefore,

\[{{P}_{1}}-{{P}_{2}}=g\text{ }R'({{\rho }_{A}}-{{\rho }_{B}})\sin \theta \]

The usage of inclined manometers is limited.

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Figure 1: Short Tube Vertical Evaporator.

Working Principle of Short Tube Vertical Evaporator

In short tube vertical evaporator, liquid feed is passed through a set of vertical tubes. The externally supplied steam heats the liquid feed within the tubes which begins to boil. Boiling of the liquid causes it to evaporate. The vapours so formed, are removed from the outlet at the top while concentrated liquid is collected from the bottom of the evaporator.

Construction of Short Tube Vertical Evaporator

Evaporator is cylindrical, dome-shaped and is made up of cast iron. The equipment consists of inlets for feed and steam and outlets for vapour, condensed gases and concentrated product. The body of the evaporator contains a set of vertical tubes (known as calandria) which are 4-6 feet in length and 2-3 inches in diameter. These tubes are held by upper and lower tube sheets.

Working of Short Tube Vertical Evaporator

Liquid feed is introduced through the feed inlet and its level is maintained just above the tubes. Steam supplied through the steam inlet circulates in between the tubes and transfers its heat to the liquid within the tubes. Upon boiling, the liquid moves up through the tubes and then flows down the central compartment. Such movement helps to maintain the circulation of the liquid. The concentrated product formed is collected from the bottom of the evaporator.

Advantages of Short Tube Vertical Evaporator

1. Heating surface area is 10-15 times more when compared to the evaporating pan.
2. Associated with high heat transfer coefficient (HTC) as it involves continuous circulation of the hot liquid.
3. Rate of evaporation can be enhanced by linking the evaporator with a condenser and a receiver.

Disadvantages of Short Tube Vertical Evaporator

1. Installation cost of the equipment is high.
2. Difficult to clean and maintain when compared to evaporating pan.
3. Poor heat transfer when viscous liquids are used.
4. The material used for constructing the evaporator body is cast iron, which is not resistant to corrosion.
5. Occupies more floor space.
6. Boiling point of the liquid is increased, thereby the heat required for evaporation also increases.
7. Not suitable for suspensions.

Applications of Short Tube Vertical Evaporator

1. It is used in the evaporation of sugar cane juice.
2. It is used in the manufacturing of cascara extract, caustic soda, salt and sugar etc.

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Figure 1: Sieve Shaker Machine.

Working Principle of Sieve Shaker Machine

In Sieve Shaker Machine, a set of standard screens as per USP and IP specifications are stacked on a mechanical shaker device. The entire set-up is then subjected to different modes of agitation (vibrating, oscillatory or reciprocating or to and fro and gyratory), so as to increase the rate of size separation process.

Construction and Working of Sieve Shaker Machine

Sieves are stacked one above the other in such a way that the most coarse sieve is placed on the top, followed by sieves with decreasing aperture sizes (see Figure 1). In other words, they are arranged in increasing order of sieve number and decreasing aperture size. A receiving pan is placed at the bottom of the screen to collect the last fraction of powder. A specified sample to be size separated is placed on the topmost sieve and is covered to avoid loss of material during agitation. The entire sieve set is placed on a mechanical sieve shaker. The setup is vigorously agitated for a specified period of time. The fraction of material collected on each screen is weighed. The weight of each fraction is termed as weight fraction of the total sample.

Advantages of Sieve Shaker Machine

1. Simple and easy to handle
2. Low cost (cheaper).

Disadvantages of Sieve Shaker Machine

1. Particles up to 50 μm size can be obtained.
2. If the powder to be analyzed is moist then the sieve apertures get clogged due to which the sieving efficiency decreases.
3. As the particles collide with one another, it may lead to attrition and the particles may be further size reduced. This may give false results.

Applications of Sieve Shaker Machine

Sieve shaker apparatus is employed for sieve analysis to determine the efficiency of the size reduction equipment.

Modifications of Sieve Shaker Machine

Mechanical sieve shaker machine can be replaced by an electromagnetic sieve shaker and sonic sifter (sonic oscillations are used). These give accurate results. The machine is modified in such a way that a mechanical pulse action is created, so as to avoid any blinding or agglomeration.

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