What is hausner ratio?
Andrew Campbell
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The Hausner ratio is a number that is correlated to the flowability of a powder or granular material. It is named after the engineer Henry H. Hausner.
How is Hausner ratio calculated?
The Hausner ratio6 expressed as the tap density divided by the bulk density, Hr = ρtap/ρb, and related Carr index,7 CI = 1 − 1/Hr, are used to indicate the flowability of granular powders in a wide variety of industries.
What is Carrs index formula?
Carr's Index Formula
Carr_Index = (ρtapped-ρbulk)/ρtapped*100. With. ρtapped : the tapped bulk density of the material (kg/m3)
What is significance of Carr's index?
The Carr index (also: Carr's index or Carr's Compressibility Index) is an indication of the compressibility of a powder. ... A Carr index greater than 25 is considered to be an indication of poor flowability, and below 15, of good flowability.
What is cohesive powder?
Abstract. It is well known that powders become more 'cohesive' as their mean particulate size decreases. This phenomenon is evidenced by such characteristics as poor flowability, clumping, avalanching, difficulty in fluidizing, and formation of quasi-stable, low-density configurations that are easily compacted.
CARR'S INDEX, HAUSNER'S RATIO AND ANGLE OF REPOSE, MOST IMPORTANT TOPIC FOR EXAMINATIONS GPAT, NIPER
What is Angle of Repose in pharma?
Angle of Repose: Under the static balance, the angle between the slope of a powder pile and the horizontal plane is Angle of Repose. It is measured when the powders fall to a surface via gravity and form a cone. ... The smaller the Angle of Repose is, the better the flowability of the powders.
What is porosity of powder?
Porosity is defined as the ratio of the total pore volume to the apparent volume of the particle or powder (excluding interparticle voids).
What is flow property of powder?
Powder flow, also known as flowability, is defined as the relative movement of a bulk of particles among neighboring particles or along the container wall surface. In other words, powder flowability refers to the ability of a powder to flow in a desired manner in a specific piece of equipment...
What does tapped density mean?
The tapped density is an increased bulk density attained after mechanically tapping a container containing the powder sample. The tapped density is obtained by mechanically tapping a graduated measuring cylinder or vessel containing the powder sample.
How can I improve the flow property of powder?
As particle size increases, flow of the powders also increases and after certain level works as free flowing. Appropriate blend of coarse and fine particles or in other words selection of particle size distribution improves the flow properties.
What is the reciprocal of bulk density?
The relationship of bulk density and porosity is reciprocal. As one increases, the other decreases.
What is the use of Hausner ratio?
The Hausner ratio6 expressed as the tap density divided by the bulk density, Hr = ρtap/ρb, and related Carr index,7 CI = 1 − 1/Hr, are used to indicate the flowability of granular powders in a wide variety of industries.
What is Angle of Repose used for?
Angle of repose is another important physical property used for characterization of the bulk of particulate foods such as seeds, grains, flours, grits, and fruits. When granular solids are piled on a flat surface, the sides of the pile are at a definite reproducible angle with the horizontal leveled surface (Fig. 3.8).
What is compressibility of powder?
The term 'compressibility' is defined as the ability of a powder to decrease in volume under pressure, and the term 'compactibility' is defined as the ability of the powdered material to be compressed into a tablet of specified strength (i.e. radial tensile strength or deformation hardness).
What do you mean by porosity?
1a : the quality or state of being porous. b : the ratio of the volume of interstices of a material to the volume of its mass. 2 : pore.
How is porosity measured?
Porosity is the percentage of void space in a rock. Porosity is the percentage of void space in a rock. It is defined as the ratio of the volume of the voids or pore space divided by the total volume. It is written as either a decimal fraction between 0 and 1 or as a percentage.
How do you calculate porosity?
Porosity = ( ( Total Volume - Volume of the Solid ) / Total Volume ) x 100%. A larger percentage means that the rock has the ability to hold more water.
How do you calculate angle of repose?
tan-1(2h/d) - h is the height of the pile of powder and d is the Diameter. Using a scientific calculator, multiply the height by 2 and divide this value by the diameter. Then, hit the inverse tan key or tan-1 and the answer just calculated. This will give you the angle of repose.
What is the difference between angle of repose and angle of surcharge?
The Angle of Repose is the angle the material makes with the horizontal when dumped in a pile, such as a stockpile or a stationary belt . ... The Angle of Surcharge (As) is the angle the material makes with the horizontal when the material is bumped or moving, such as on a moving conveyor belt .
How do you reduce angle of repose?
The calculated angle of salt should be somewhere in between those. This variation is due to the different sizes and shapes of the material particles. Increasing particle size will generally decrease the angle of repose.
What is mixing of powder?
A powder is an assembly of dry particles dispersed in air. If two different powders are mixed perfectly, theoretically, three types of powder mixtures can be obtained: the random mixture, the ordered mixture or the interactive mixture.
What is an ordered mix?
The concept of ordered mixing involves the mixing of small cohesive particles to a considerable degree of homogeneity. ... An ordered mix is obtained when the drug, in a finely dispersed state, adheres to the surface of substantially larger carrier particles.
What is Spatulation method?
spatulation - Spatulation is the mixing of powders and semi-solids (ointments, creams, etc.)on an ointment pad or slab using a spatula. ... When using this method, the smallest quantity of active ingredient is mixed thoroughly with a proportion quantity of the diluent or base on the ointment slab.
