Book Description

This method is applicable to the sieve test for dustable and wettable powders of pesticides. 2 Method 2.1 Dry sieving method (applicable to powders) 2.1.1 Method summary: Dry the sample in the oven to constant weight and cool it naturally to room temperature. After the sample and the atmosphere reach humidity equilibrium, weigh a specimen. Sieve to the end point with a test sieve of appropriate hole size. Weigh the residue in the sieve. Calculate the fineness (if the dried sample is easy to absorb moisture, the sample must be placed in a desiccator to cool, and the contact between the sample and the atmospheric environment shall be minimized to complete the screening). 2.1.2 Instruments Test sieve: appropriate aperture, with matching receiving plate and cover. Glass dish: known mass. Brush: 2.5 cm soft flat brush. Constant temperature oven: temperature control accuracy within 100¡ãC is ¡À2¡ãC. Desiccator. 2.1.3 Determination steps 2.1.3.1 Sample preparation Adjust the oven to the appropriate temperature according to the characteristics of the sample. A sufficient amount of sample is dried in the oven to constant weight. The sample is then naturally cooled to room temperature and equilibrated with atmospheric humidity for later use. If the sample absorbs moisture easily, it shall be cooled to room temperature in the desiccator. And try to minimize contact with the atmospheric environment. 2.1.3.2 Determination GB/T 16150-1995 www.ChineseStandard.net ? Buy True-PDF ? Auto-delivery. Page 4 of 6 Weigh 20 g of specimen (accurate to 0.1 g). Place in a test sieve of appropriate aperture that fits the receiving plate. Close the lid. Carry out the test in one of two ways. a. Vibrating screen method Install the test sieve on the vibrating screen machine and vibrate, while tapping the left and right sides of the receiving plate alternately. After 10 mi