This method is applicable to the determination of the fineness of pesticide powders and wettable powders. GB/T 16150-1995 Method for determination of fineness of pesticide powders and wettable powders GB/T16150-1995 Standard download decompression password: www.bzxz.net

1 Scope of application
National Standard of the People's Republic of China
Determination method of fineness of pesticide powders and wettable powdersSeive test for dustable and wettable powders of pesticides
This method is applicable to the determination of fineness of pesticide powders and wettable powders. 2 Determination method
2.1 Dry sieving method (applicable to powders)
GB/T16150—1995
2.1.1 Summary of method: The sample dried to constant weight in the oven is naturally cooled to room temperature, and after the sample reaches humidity equilibrium with the atmosphere, the sample is weighed and sieved to the end point with a test sieve of appropriate aperture, and the residue in the sieve is weighed to 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 atmosphere is minimized to complete the sieving). 2.1.2 Apparatus
Test sieve: appropriate aperture, with matching receiving tray and lid; Glass blood: known mass;
Brush: 2.5 cm soft flat brush;
Hot oven: within 100℃, temperature control accuracy is ±2℃; Desiccator.
2.1.3 Determination steps
2.1.3.1 Sample preparation
According to the characteristics of the sample, adjust the oven to a suitable temperature, place a sufficient amount of sample in the oven to dry to constant weight, and then let the sample cool naturally to room temperature and reach equilibrium with the atmospheric humidity for use. If the sample is easy to absorb moisture, it should be placed in a desiccator to cool to room temperature and minimize contact with the atmospheric environment. 2.1.3.2 Determination
Weigh 20g of sample (accurate to 0.1g), place it in a test sieve with an appropriate aperture that matches the receiving tray, cover it with a lid, and conduct the test in one of the following two methods.
a. Screening machine method
Install the test sieve on the screen vibrator and vibrate it, while tapping the left and right sides of the receiving tray alternately. After 10 minutes, turn off the screen vibrator, let the dust settle for a few seconds, then open the screen cover, use a brush to clean all the materials that block the screen mesh, and disperse the soft lumps in the screen, but do not crush the hard particles. Cover the screen cover, turn on the screen machine, and repeat the above process until the sieve material is less than 0.01g in 2 minutes. Move the residue in the screen to glass blood and weigh it. b. Hand screening method
Hold the screen cover and both sides of the receiving tray with both hands at the same time, and on the operating table with a rubber cover, repeatedly contact the bottom of the left and right sides of the receiving tray with the operating table to vibrate the screen, and adjust the sieve position in the clockwise direction (or counterclockwise direction) from time to time. Before opening the cover, let the dust settle for a few seconds, use a brush to clean the materials that block the screen mesh, and disperse the soft lumps, but do not crush the hard particles. Repeat the sieving process until less than 0.01 g of material passes through the sieve within 2 minutes. Transfer the residue in the sieve to a glass dish and weigh it. Approved by the State Administration of Technical Supervision on December 21, 1995 638
Implementation on August 1, 1996
2.2 Wet sieving method (applicable to wettable powders) 2.2.1 Summary of the method
GB/T 16150—1995
Place the weighed sample in a beaker to moisten and dilute it, pour it into the moistened test sieve, rinse it directly with a gentle stream of tap water, then place the test sieve in a basin of water to continue washing, transfer the residue in the sieve to a beaker, dry the residue, weigh it, and calculate the fineness. 2.2.2 Apparatusbzxz.net
Test sieve: appropriate aperture, with matching receiving tray and cover, beaker: 250mL, 100mL;
Oven: temperature control accuracy within 100℃ ±2℃; glass rod: with rubber cover;
Dryer.
2.2.3 Determination steps
2.2.3.1 Wetting of sample
Weigh 20g sample (accurate to 0.1g), place it in a 250mL beaker, add about 80mL tap water, stir with a glass rod to make it completely wet. If the sample is resistant to wetting, add an appropriate amount of non-polar wetting agent. 2.2.3.2 Wetting of test sieve
Immerse the test sieve in water to completely wet the wire cloth. If necessary, add an appropriate amount of non-polar wetting agent to the water. 2.2.3.3 Determination
Dilute the moistened sample in the beaker with tap water to about 150mL, stir evenly, and then pour all of it into the moistened standard sieve. Wash the beaker with tap water, and pour the washing water into the sieve until the coarse particles in the beaker are completely moved into the sieve. Use a gentle tap water flow from a rubber hose with a diameter of 9-10mm to rinse the sample on the sieve. The water flow rate is controlled at 4-5L/min, and the outlet at the end of the rubber hose is kept flush with the edge of the sieve. During the sieving process, keep the water flow aimed at the sample on the sieve to fully wash it (if there are soft lumps in the sample, use a glass rod to gently press it to disperse it), and wash until the water passing through the test sieve is clear and transparent. Then move the test sieve to a basin filled with tap water, move the washing sieve edge up and down, and keep it above the water surface. Repeat until no material is sieved within 2 minutes. Discard the sieved material, and rinse the residue in the sieve to one corner and then transfer it to a 100mL beaker with constant weight. Let it stand until the particles in the beaker settle to the bottom, then pour off most of the water, heat it, evaporate the residue to near dryness, dry it in an oven at 100°C (or other appropriate temperature according to the physical and chemical properties of the product) to constant weight, take out the beaker, place it in a desiccator and cool it to room temperature, and weigh it.
2.3 Calculation
The fineness (X)% of powders and wettable powders is calculated as follows: X = ml=m2 × 100
-the mass of the powder (or wettable powder) sample, g; where: m
-the mass of the residue in the glass (or beaker), g. m2—
2.4 Allowable difference
The difference between the results of two parallel determinations should be within 0.8%. 639
Additional instructions:
GB/T16150-1995
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard was drafted by Shenyang Institute of Chemical Industry. The main drafters of this standard are Wang Yufan, Xing Hong and Wu Qi. From the date of implementation of this standard, the former Ministry of Chemical Industry standard HG2-896-76 (83) "Determination of fineness of pesticide powder" will be invalid. This standard is equivalent to the International Pesticide Analysis Cooperative Committee method CIPACMT59.
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