ISO8130-1:1992 Determination of particle size distribution by screening method

(1 Scope

This standard specifies the method for determining the particle size distribution of powdered materials by sieving. This method can distinguish particle sizes in the range of 32 to 300 µm.

This method can also be used as a simplified procedure, that is, a test for determining the sieve residue (pass/fail) on a single sieve.

(2) Instrument

Test sieve: There is a circular sieve with a diameter of 200mm. The walls and mesh of the test sieve shall be of metal. The range of diameter should be between 32~300µm, and should meet the requirements of IS0565 supplementary dimensions (see Appendix A). The test sieve shall have a transparent difference.

The choice of mesh will depend on the actual situation. If the particle size distribution of the sample is approximately known, it is necessary to use only test sieves appropriate to the particle size range. In order to obtain sufficient data in special cases, it is also possible to obtain a test screen that prohibits the selection. Appropriate details should be agreed between the parties concerned.

Airflow sieve (see Figure 6-11): It consists of a round knot-shaped cylinder with a test sieve. There should be an outlet and an inlet at the bottom of the cylinder (connected to the exhaust fan), so that the airflow can enter and exit. The air inlet should be connected with an air injection device, and the installation speed should be 20~25r/min. It should be composed of sharp slit nozzles. The inlet and outlet should be Mounted longitudinally against the screen at the bottom of the screen. When the air spray device is rotated, the air flow continuously passes through the screen from below to prevent the powder coating particles from clogging the test screen. The airflow exits through the outlet, taking away the smaller particles that pass through the sieve at the same time.

Airflow can be controlled by adjusting the slit at the outlet.

Timer (that is, stopwatch): it can be accurate to 1s or more, and it can be opened by connecting the air screen and the motor with a breaker.

Balance: can accurately weigh to 0.01g.

Wooden hammer: Wooden hammer of lightweight construction with plastic head, suitable for knocking off powder adhering to test sieves and lids.

Magnifying glass: at least 5 times the magnification effect.

Ultrasonic cleaning tank.

(3) Sampling

Take representative samples of the test product according to the procedures specified in 1S0842.

(4) Preparation of test sieve

Use a magnifying glass to check whether the test sieve is clear, if it is damaged, and there should be no material that plugged the sieve during the previous measurement.

If it is considered necessary to clean the test sieve, it is recommended to use Zhao Shengbo cleaning tank for cleaning.

(5) Operation steps

Two assays were performed.

Weigh the test sieve together with the transparent cover, accurate to 0.0 lg.

Weigh 20g sample, accurate to 0.0lg (if the sample sieve diameter used is less than 90µm, 10g sample can be weighed).

Fix the selected test sieve at the position of the airflow sieve, and transfer the sample to the test sieve. Cover the transparent cover, reduce the pressure of the system to 2kPa ± 0.3kPa, and start to rotate the nozzle. Unless otherwise specified, the operating time of the instrument is 300s ± 15s.

If it can be proved that the ultra-fine powder passes through the test sieve within 180s ± 15s, it is allowed to use this shorter sieving time, and write this sieving time into the test report. If any material adheres to the sieve wall or transparent cover, lightly tap it with a wooden hammer to knock off the adhered powder.

If it is difficult to sieve very fine materials, 0.2% (based on the original sample mass of the sample) of a suitable very fine sieving aid (calcined magnetic dioxide or alumina) can be added to the sample Help sift. The quality of these additional materials has to be corrected as they will pass through the sieve.

At the end of the test, let the air pressure slowly reach equilibrium with the room pressure. Remove the cover, and weigh the test sieve with the sieve residue to an accuracy of 0.0 lg.

In order to determine the particle size distribution expressed by mass, first measure the mass retained on the selected smallest aperture test sieve. According to the operation method in the operation steps, use a new sample to repeat the measurement for each size test sieve from bottom to top within the range required by the report.

(6) Indication of results

Calculate the sieve residue on each test sieve according to formula (6-6), expressed in mass percentage, R:

If the difference between the two measurements is greater than 3% (absolute value), re-operate according to the operating procedures.

Calculate the average of two valid determinations and report the result as a rounded number. The results of a series of determinations using test sieves of different sizes may be reported in tabular or graphical form.

When presenting results graphically, it is recommended to use a R0sin-Rammler-Sperling-Bennett (RRSB) diagram to plot the data.