Size Separation and Official Standards for Powders
90 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is size separation in a mixture?

Size separation is a unit operation that involves the separation of a mixture of particles of various sizes into two or more portions by means of screening surfaces.

What are three other terms used to describe size separation?

Sieving, sifting, classifying or screening.

What is the primary factor determining particle size separation?

Physical differences between the particles such as size, shape and density.

Size reduction of a solid material always results in particles of the same size.

<p>False</p> Signup and view all the answers

What is a common application of size separation in the pharmaceutical industry?

<p>To determine particle size and size distribution, which are useful in the production of tablets and capsules.</p> Signup and view all the answers

What is the purpose of using size separation in testing a size reduction equipment or process?

<p>To test the efficiency of a size reduction equipment or process.</p> Signup and view all the answers

What are some process conditions that can be optimized using size separation?

<p>Methods of agitation, time of screening, feed rate etc.</p> Signup and view all the answers

What are two benefits of using size separation?

<p>To recover valuable products or byproducts, and to prevent environmental pollution.</p> Signup and view all the answers

What official standards are used to classify powders based on their particle size?

<p>Pharmacopoeia.</p> Signup and view all the answers

How many grades of powders are defined by pharmacopoeia based on sieve size?

<p>Five</p> Signup and view all the answers

What kind of powders are characterized by having all particles that pass through a No. 10 sieve and not more than 40% pass through a No. 44 sieve?

<p>Coarse powders.</p> Signup and view all the answers

What kind of powders are characterized by having all particles pass through a No. 22 sieve and not more than 40% pass through a No. 60 sieve?

<p>Moderate coarse powder.</p> Signup and view all the answers

What kind of powders are characterized by having all particles pass through a No. 44 sieve and not more than 40% pass through a No. 85 sieve?

<p>Moderate fine powder.</p> Signup and view all the answers

What kind of powders are characterized by having all particles pass through a No. 120 sieve?

<p>Very fine powder.</p> Signup and view all the answers

It is easier to obtain fine powder than coarse powder.

<p>True</p> Signup and view all the answers

What are some pharmaceutical processes where various grades of powders are used?

<p>Extraction of active constituents and in the formulation of various types of dosage forms.</p> Signup and view all the answers

What type of preparations requires very fine powders to avoid irritation?

<p>Preparations for external application to the skin, such as ointments, pastes, creams, lotions, liniments, dusting powders, and ophthalmic preparations.</p> Signup and view all the answers

The rate of absorption of a drug is independent of particle size.

<p>False</p> Signup and view all the answers

What type of particle size is used for oral preparations like suspensions, powders, tablets, and capsules?

<p>Fine powder.</p> Signup and view all the answers

Why are large size particles sometimes used when sustained action of a drug is desired?

<p>Large size particles release the drug more slowly, enabling a sustained effect for a longer duration, leading to a controlled release of the active ingredient.</p> Signup and view all the answers

What are sieves used for in the pharmaceutical industry?

<p>Size separation.</p> Signup and view all the answers

What is the primary consideration when selecting a sieve?

<p>The size and shape of the aperture opening.</p> Signup and view all the answers

What is the most common type of mesh arrangement used in pharmaceutical sieves?

<p>Square</p> Signup and view all the answers

Which of these sieves are commonly used in pharmaceutical processing?

<p>All of the above</p> Signup and view all the answers

What are woven wire sieves commonly used for in pharmacy practice?

<p>General-purpose sieves.</p> Signup and view all the answers

Which of these are types of woven wire sieves?

<p>All of the above</p> Signup and view all the answers

What type of woven wire sieves are typically used for fine sieving?

<p>Metal wire woven sieves.</p> Signup and view all the answers

What is an example of a common hand sieve?

<p>A hand sieve.</p> Signup and view all the answers

Coarse sieves typically use a single crimp on the wire to ensure alignment.

<p>False</p> Signup and view all the answers

What type of sieves are made from twisted multi-strand fibers?

<p>Bolting cloth sieves.</p> Signup and view all the answers

What is a common application for bolting cloth sieves?

<p>The separation of fine powders.</p> Signup and view all the answers

What type of screen utilizes bolting cloth?

<p>Hummer Screen.</p> Signup and view all the answers

What is the primary method of particle separation in screening?

<p>Passing the particles through a series of sieves of uniform size.</p> Signup and view all the answers

What force drives the particles through the sieve openings?

<p>Gravity.</p> Signup and view all the answers

Larger particles can easily pass through the openings, even in fine sieves.

<p>False</p> Signup and view all the answers

What methods are used to enhance the sieving process for fine powders?

<p>Inducing some type (mode) of motion (movement) to the particles.</p> Signup and view all the answers

What are the three main methods used to assist particle movement during sieving?

<p>All of the above</p> Signup and view all the answers

What is the purpose of shaking the material during sieving?

<p>To ensure quick and complete sieving across the entire area of the sieve.</p> Signup and view all the answers

What are the types of agitation methods used in sieving?

<p>Oscillation and vibration.</p> Signup and view all the answers

What type of motion is commonly used in oscillation?

<p>Reciprocal motion.</p> Signup and view all the answers

How is reciprocating motion induced in a sieve?

<p>By means of an ordinary eccentric on a rotating shaft.</p> Signup and view all the answers

What is the purpose of vibration in sieving?

<p>To impart rapid vibration to the particles, aiding their passage through the sieve openings.</p> Signup and view all the answers

What type of screens are particularly useful in the chemical industry?

<p>Electrical vibrated screens.</p> Signup and view all the answers

Agitation methods are generally continuous processes.

<p>False</p> Signup and view all the answers

What are the advantages of agitation methods?

<p>They are inexpensive and simple to implement.</p> Signup and view all the answers

What are the disadvantages of agitation methods?

<p>All of the above</p> Signup and view all the answers

What is the purpose of using a brush in brushing methods?

<p>To move the particles on the surface of the sieve and to keep the meshes clear.</p> Signup and view all the answers

What type of sieve is the brush rotated in the middle of?

<p>A circular sieve.</p> Signup and view all the answers

What type of brush is rotated on the longitudinal axis in a horizontal cylindrical sieve?

<p>A spiral brush.</p> Signup and view all the answers

For what type of powder are brush sifters commonly used?

<p>Greasy or sticky powders.</p> Signup and view all the answers

What method uses centrifugal force to separate particles?

<p>The centrifugal method.</p> Signup and view all the answers

In the centrifugal method, what force throws the particles outwards?

<p>Centrifugal force.</p> Signup and view all the answers

What is the role of the air currents generated by the air jet in the centrifugal method?

<p>To help separate the particles.</p> Signup and view all the answers

What are some examples of equipment that utilize the principle of centrifugal force for separation?

<p>Cyclone separators and air separators.</p> Signup and view all the answers

What are the advantages of the centrifugal method?

<p>All of the above</p> Signup and view all the answers

What is the purpose of sieve analysis?

<p>To determine the particle size distribution of a powder.</p> Signup and view all the answers

What are some applications of sieve analysis?

<p>Quality control, testing the efficiency of size reduction equipment or processes, and selecting a suitable sieve system for commercial equipment.</p> Signup and view all the answers

Sieve overloading can result in errors in sieve analysis.

<p>True</p> Signup and view all the answers

Insufficient time allocated for particle passage can also lead to errors in sieve analysis.

<p>True</p> Signup and view all the answers

What is the working principle of a sieve shaker machine?

<p>The powdered drug is separated according to its particle size using a number of sieves in a nest.</p> Signup and view all the answers

What types of agitation are applied to the sieves in a sieve shaker machine?

<p>Different types of agitation.</p> Signup and view all the answers

Where is the course sieve placed in the sieve shaker machine?

<p>At the top of the sieve nest.</p> Signup and view all the answers

What is the typical weight of the sample used in a sieve shaker machine?

<p>50 g.</p> Signup and view all the answers

What is the typical duration of the shaking process in a sieve shaker machine?

<p>20 minutes.</p> Signup and view all the answers

How often should the aperture size change between adjacent sieves?

<p>Based on 1/2 or 2 1/2 change.</p> Signup and view all the answers

What is the purpose of collecting the powder retained on each sieve on paper?

<p>To weigh the powder retained on each sieve and record the mesh number.</p> Signup and view all the answers

What is the working principle of a cyclone separator?

<p>Centrifugal force is used to separate solid particles from fluids.</p> Signup and view all the answers

What does the separation process in a cyclone separator depend on?

<p>Particle size and particle density.</p> Signup and view all the answers

How does the construction of a cyclone separator facilitate separation?

<p>The solid outlet is arranged at the base, while the fluid outlet is at the center of the top portion, which extends inwardly into the separator.</p> Signup and view all the answers

What is the typical feed for a cyclone separator?

<p>Solids suspended in a fluid stream.</p> Signup and view all the answers

How is the feed introduced into a cyclone separator?

<p>Tangentially at a very high velocity, creating a rotary movement within the vessel.</p> Signup and view all the answers

What force acts on the particles as they swirl in the cyclone separator?

<p>Centrifugal force.</p> Signup and view all the answers

What happens to the speed of the fluid as it moves towards the solid outlet?

<p>It diminishes.</p> Signup and view all the answers

What happens to the fluid after the solid particles are collected?

<p>It escapes from the central outlet at the top.</p> Signup and view all the answers

What are the main applications of cyclone separators?

<p>All of the above</p> Signup and view all the answers

What is the principle of a bag filter?

<p>Size separation of fines, or dust, from the milled powder is achieved in two steps.</p> Signup and view all the answers

What is the first step in the bag filter process?

<p>Passing the milled powder through a bag by applying suction.</p> Signup and view all the answers

What is the second step in the bag filter process?

<p>Applying pressure to shake the bags to remove adhering powder.</p> Signup and view all the answers

What material are the bags in a bag filter typically made of?

<p>Cotton or wool fabric.</p> Signup and view all the answers

Where are the bags suspended in a bag filter?

<p>In a metal container.</p> Signup and view all the answers

What is the purpose of the hopper in a bag filter?

<p>To receive the feed at the bottom of the filter.</p> Signup and view all the answers

What is the purpose of the discharge manifold in a bag filter?

<p>To allow exhaust through the discharge manifold.</p> Signup and view all the answers

What is the purpose of the bell-crank lever arrangement in a bag filter?

<p>To change the action from filtering to shaking.</p> Signup and view all the answers

What is the purpose of the vacuum fan during the filtering period in a bag filter?

<p>To create a pressure lower than atmospheric pressure within the vessel.</p> Signup and view all the answers

Where are the particles retained during the filtering period?

<p>Within the bags.</p> Signup and view all the answers

What is the purpose of the shaking period in a bag filter?

<p>To dislodge the particles trapped on the bag's surface.</p> Signup and view all the answers

What happens to the discharge manifold during the shaking period?

<p>It is closed.</p> Signup and view all the answers

What happens to the air during the shaking period?

<p>It enters through the top of the apparatus.</p> Signup and view all the answers

Where are the fine particles collected in a bag filter?

<p>At the conical base.</p> Signup and view all the answers

What are some applications of bag filters?

<p>All of the above</p> Signup and view all the answers

Study Notes

Size Separation

  • Size separation is a unit operation separating mixtures of different particle sizes using screening surfaces.
  • Also known as sieving, sifting, classifying or screening.
  • Based on physical differences like size, shape, and density of particles.
  • Size reduction produces different sizes of particles.
  • Applications include determining particle size and size distribution for tablets, capsules, and testing size reduction equipment efficiency.
  • Also optimizing process conditions, recovering valuable products/byproducts, and preventing environmental pollution.

Official Standards for Powders

  • Powders are categorized into five grades based on the sieve mesh size they pass through.
  • Coarse powder (10/44): Particles pass through a No. 10 sieve, with no more than 40% passing through a No. 44 sieve.
  • Moderate coarse powder (22/60): Particles pass through a No. 22 sieve, with no more than 40% passing through a No. 60 sieve.
  • Moderate fine powder (44/85): Particles pass through a No. 44 sieve, with no more than 40% passing through a No. 85 sieve.
  • Very fine powder (120): Particles pass through a No. 120 sieve.

Sieves

  • Sieves are the simplest and most frequent size separation method.
  • Sieve types are primarily based on the aperture opening's size and shape (square mesh).
  • Common types of sieves in pharmaceutical processing are woven wire sieves, bolting cloth sieves, closely spaced bars/screens, and punched plates.
  • Woven wire sieves are general-purpose and widely used in pharmacy practice (plain weave, twill weave).

Modes of Motion in Size Separation

  • Screening is the separation of particles based on size.
  • Basic techniques involve passing particles through sieves of uniform sizes.
  • Particle movement can be assisted by three methods: agitation, brushing, and centrifugal force.

Agitation Methods

  • Methods include oscillation (reciprocal movement back and forth) and vibration.
  • Oscillation is a simple method, but particles can roll on the surface of the sieve.
  • Vibration (high-speed) using electrical/mechanical devices accelerates the sieving process.

Brushing Methods

  • A brush moves the particles across the sieve surface to clear the meshes.
  • Brushes can be rotated in a circular or spiral motion, depending on the sieve type.

Centrifugal Methods

  • Rotors inside a vertical cylindrical sieve create centrifugal force.
  • Particles are thrown outwards, with particles of different sizes collecting in different areas.
  • Cyclone separators, using centrifugal force, separate solid particles from fluids (usually air or water) efficiently.

Testing of Powder

  • Sieve analysis tests powder size separation for quality control.
  • Used to assess raw materials and the efficiency of size reduction equipment or commercial processes.

Sieve Shaker Machine

  • The shaker machine uses sieves arranged in a nest with the coarsest at the top.
  • Powder is placed on the top sieve, and the sieve is shaken for a set time to separate particles based on size.

Cyclone Separator

  • Separates solid particles from fluids.
  • Based on centrifugal force, with tangential inlet for fluid flow and central outlet for separated solids.
  • Used in size separation of solids in gases and liquids, separating heavy/coarse and fine particles.

Bag Filter

  • Achieves size separation with two steps: using a bag to pass through particles then using pressure to remove the adhering material.
  • Bags suspended in a container to separate solid particles from fluids (usually air).
  • Collects fine particles at the bottom of the container while cleaned air passes through.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Size Separation PDF

Description

This quiz covers the principles of size separation in processes like sieving and classifying. Learn about the various categories of powders based on their sieve mesh size and applications in pharmaceuticals and environmental management. Test your understanding of particle size distribution and official grading standards for powders.

More Like This

Size Exclusion Chromatography Quiz
2 questions

Size Exclusion Chromatography Quiz

StableDream avatar
StableDream
Size Separation Techniques Quiz
6 questions

Size Separation Techniques Quiz

WorkableTanzanite avatar
WorkableTanzanite
Particle Size Separation Methods
40 questions

Particle Size Separation Methods

FlawlessRainbowObsidian avatar
FlawlessRainbowObsidian
Particle Size Separation Methods Quiz
10 questions

Particle Size Separation Methods Quiz

SatisfyingDouglasFir avatar
SatisfyingDouglasFir
Use Quizgecko on...
Browser
Open
Browser
Browser