Particle Size Analysis Using by Sieve Method | Determination of the Appearance

The 800 mesh sieves with a lid and receiver, free of film, grease, or other water, repellent material, Petri dish, stoppered conical/flat bottom flask. Sieve analysis, Laboratory test sieves.

Reagents: 10-15% AOS or any detergent solution.

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Sieve Analysis Procedure

1. Weigh accurately about 10 g of the material and transfer it into a 250 ml stoppered conical flask.

2. Add to it about 50 ml of AOS solution (approximately 10-15%). Shake well to have effective dispersion.

3. Take a clean dried sieve of 800 mesh. Pour the talc dispersion into the sieve and place it under a running water tap.

4. Rinse the conical flask with approximately 50 ml of water and pour the remaining contents into the sieve.

5. Repeat the operation to ensure complete transfer of talc from the flask.

6. Rub gently the dispersion with figures on the sieve for easy passing through the mesh.

7. Continue the operation taking care to avoid any spillage, till the entire quantity that can pass through the sieve is passed off.

8. To have better and more effective transfer pour 10-15 ml of AOS solution in the sieve under running water.

9. After complete washing the sieve along with the retention, if any, is dried at 105°C for 1 hour. Ensure completion of drying.

10. Transfer carefully the dried-up retention in a clean and previously tared Petri dish; weigh the same and calculate the percentage retention on a sieve.

Sieve analysis Calculation:

                                                   W1

Residue on 800 mesh sieves = ------ x 100 % w/w

                                                     W

Where,

W1 = weight of the residue on 800 mesh sieve.

W = weight of sample taken.

Microscopic examination Procedure

A 5.0 mg sample is placed on a microscope slide and spread evenly over the whole cover glass.

The full test surface is examined qualitatively at low magnification (e.g. x50) for any inhomogeneities or agglomerations, then ten non-overlapping fields of vision are evaluated at x200 magnification along one diameter of the observation surface and the mean value is

Calculated of mesh size.

The mean figures from ten observation surfaces must include no more than five particles greater than 10 μm and none over 100 μm.

Sieve Analysis for Particle Size Distribution

This method applies to the determination of the particle size distribution of powder raw materials used in the manufacture of mosquito coils.

Sieve Analysis Principle

This test method determines the percentages of particles in a sample which are graded into different size ranges. This is achieved by sieving a prescribed amount of powder through a series of sieves of selected mesh sizes using a sieve shaker for a prescribed period of time.

Equipment for sieve analysis

1) Clean, dry sieves (free of film, grease or other contaminants) of agreed mesh sizes (British Standard)

2) Sieve lid and bottom

3) Balance

4) Clean weighing dishes and a beaker

5) Mechanical sieve shaker

6) Brush

Procedure :

A) Sampling

Refer to 'Sampling of Mosquito Coil Powdered Raw Materials' (Test Method Reference 31488)

B) Sieve analysis Test Procedure

1) Stack the sieves, including the bottom, according to their ascending mesh sizes (ie smallest aperture at the bottom, largest aperture at the top)

2) Place a clean beaker on the balance and tare the balance

3) Accurately weigh 100g of sample into the beaker

4) Carefully transfer all of the contents of the beaker into the top sieve

5) Place the sieve lid on the top sieve, then place the stack of sieves on the sieve shaker and secure it properly

6) Switch on the sieve shaker and shake the sieves for 20 minutes

7) After stopping the sieve shaker, allow the sieves to stand for about ten minutes before opening to ensure that all dust settles

8) Transfer the material retained in the first sieve into a clean, weighed dish, using a brush to ensure that all material is transferred

9) Record the weight of this retained material, W1 (g)

10) Repeat step 8 for all the other sieves, and the bottom catch dish, recording the weight of material for each particle size fraction

11) The total weight of powder collected in the sieves and bottom should be very close to 100g. That is, there should be very little loss during the sieving and transfer process

12) Calculate the percentage of material retained by each sieve and that passed by the last sieve (the amount collected in the bottom) as below

13) Suggested sieves to be used for the analysis are (Refer to specification for actual sieve sizes) :

Sieve No Mesh Size (BS)

A 60

B 100

C 200

D 300

E Passed through 300 (<300)

Calculation of Sieve analysis:

For each Sieve determine the amount retained as below:

Fraction of Sample Retained on Sieve X (%) = W1 x 100/100

Where:

X is each of sieves A, B, C, D and E

W1 is the amount of sample retained on the particular sieve

Result :

The Particle Size Distribution for the sample is determined as below :

Fraction of Sample greater than 60 mesh = A%

Fraction of Sample greater than 100 mesh = (A + B)%

Fraction of Sample greater than 200 mesh = (A + B + C)%

Fraction of Sample greater than 300 mesh = (A + B + C + D)%

Fraction of Sample smaller than 300 mesh = E%

The total of A, B, C, D, and E should be 100%

Determination of the appearance of a powder by a visual evaluation.

The sample is visually examined against a set of criteria and against a suitable reference standard to determine its acceptability.

Safety 

Observe proper laboratory safety rules, personal protection, and chemical handling procedures at all times.

Read MSDS before handling chemicals and products.

Apparatus

Suitably sized beakers

Procedure for the appearance of a powder 

1) Read the specifications for the product being tested.

2) Pour the product out into a small beaker.

3) Compare the sample to the description in the specification. Pay particular attention to:

- colour

- texture

- any foreign matter

- any lumps

4) Compare the sample to the standard reference sample.

Results:

Report the sample as comparable or not comparable to the reference standard