How to identify the national standard of urea

How to identify urea national standard? This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of urea. This standard applies to urea synthesized from ammonia and carbon dioxide. Its main uses are agricultural fertilizers, plastics, resins, coatings, pharmaceuticals and other industrial sectors of raw materials. Molecular formula: CO(NH2)2 Relative molecular mass: 60.055(according to the International Table of Relative Atomic Mass, 1987)2 Reference standard GB/T 2441 Urea-Determination of total nitrogen content-Titrimetric method after distillation GB/T 2443 Urea-Determination of biuret content-Spectrophotometric method GB/T 2444 Urea-Determination of water content-Karl Fischer method GB/T 2445 Urea for industrial use-Determination of iron content-Phenanthrene? GB/T 2446 Determination of alkalinity of urea for industrial use Volumetric method GB/T 2447 Determination of water-insoluble matter content of urea for industrial use Gravimetric method GB/T 2448 Determination of particle size of urea Sieving method GB 8569 Packaging of solid chemical fertilizers GB/T 13256 Determination of sulfate content of urea for industrial use Visual turbidimetric method 3 Technical requirements 3.1 Appearance: granular or crystalline 3.2 Urea shall comply with the requirements of Table 1: Table 1 Urea technical index % Index name Industrial use Agricultural high-quality products First class qualified products First class qualified products Color white or light Total nitrogen (N) content (dry basis) ≥ 46.3 46.3 46.3 46.3 46.0 Biuret content ≤ 0.5 0.9 1.0 0.9 1.0 1.5 Moisture (H2O) content ≤ 0.3 0.5 0.7 0.5 0.5 1.0 Iron content (calculated as Fe) ≤ 0.0005 0.0005 0.0010 Alkalinity (as NH3) ≤ 0.01 0.02 0.03 Sulfate content (calculated as SO4 -2) ≤ 0.005 0.010 0.020 Water insoluble content ≤ 0.005 0.010 0.040 Particle size (φ0.85~2.80mm) ≥ 90 90 90 90 90 Note: Crystalline urea does not control particle size indicators. 4 Test methods 4.1 Determination of total nitrogen content shall be carried out according to GB/T 2441. 4.2 The determination of biuret content shall be carried out according to GB/T 2443. 4.3 The determination of moisture shall be carried out in accordance with GB/T 2444. 4.4 The determination of iron content shall be carried out in accordance with GB/T 2445. 4.5 The alkalinity shall be determined according to GB/T 2446. 4.6 The determination of sulfate content shall be carried out according to the provisions of GB/T 13256. 4.7 The determination of water insoluble matter content shall be carried out according to the provisions of GB/T 2447. 4.8 The determination of particle size shall be carried out in accordance with GB/T 2448. 5.1 Urea shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that each batch of urea delivered from the factory meets the requirements of this standard. Each batch of urea delivered from the factory shall be accompanied by a quality certificate in a certain format. The certificate shall include the following contents: manufacturer name, product name, trademark, product grade, batch number, production date, net weight of product and serial number of this standard. 5.2 The user has the right to conduct quality inspection on the urea received according to the provisions of this standard, and verify whether its indicators meet the requirements of this standard. 5.3 Urea is tested batch by batch. The weight of each batch shall not exceed 1000t. The customer regards uniform quality products with a certificate of quality as a batch. 5.4 Sampling method: For packaged products, when the total number of packaging bags is less than 512, the number of sampling bags shall be selected according to the provisions of Table 2; when it is greater than 512, the number of sampling bags shall be selected according to the provisions of 3×<>(N is the total number of packaging bags). When sampling, insert the sampler vertically from the center of the bag to 3/4 position to take uniform sample. Or take samples of sections from the belt conveyor at regular intervals using an automatic sampler, spoon or other suitable tool. 5.5 The samples taken shall be quickly divided into 600~ 1200g average samples by using a reducer or quartering method according to different requirements of industrial and agricultural products, and sub-packed into two clean, dry jars with ground stoppers or other containers with airtight performance. The containers shall be labeled with the name of manufacturer, product name, batch number, sampling date and name of sampling person. One for testing and one for retention for one month for inspection. Table 2 Requirements for selecting the number of sampling bags Total number of bags Minimum number of bags selected Total number of bags Minimum number of bags selected 1~10 All 182~216 18 11~49 11 217~254 19 50~64 12 255~296 20 65~81 13 297~343 21 82~101 14 344~394 22 102~125 15 395~ 450 23 126~151 16 451~512 24 152~181 17 5.6 If one of the indicators in the test results does not meet the requirements of this standard, samples should be taken from twice the number of bags for re-inspection. If the sample is taken on the belt conveyor, it shall be re-sampled and re-inspected according to the provisions of Article 5.4 for sampling in bags. As long as one of the indicators does not meet the requirements of this standard, the whole batch of urea is unqualified. 5.7 In case of disagreement between the supplier and the demander on product quality, relevant provisions of the State Bureau of Technical Supervision shall be followed. Arbitration shall be conducted in accordance with the provisions of this Standard. 6 Packaging, marking, transportation and storage 6.1 Urea is packaged in plastic woven bags (polyethylene film bags for inner bags) and composite plastic woven bags. Each bag has a net weight of 25±0.1, 40±0.2 or 50±0.2kg. The average net weight of each batch of product bag reaches 25, 40 or 50kg. The quality of urea packages shall comply with the relevant provisions of GB 8569. 6.2 The packing bag of urea shall be clearly marked with: manufacturer name, product name, trademark, net weight of product and number of this standard. 6.3 Urea can be transported by vehicles such as cars, trains and ships. Transportation tools and loading and unloading tools shall be clean, flat and free of protruding sharp objects so as to avoid puncturing and scratching packages. 6.4 Urea should be stored in a smooth, cool, ventilated and dry warehouse, and the packaging should be stacked neatly, and the stacking height should be less than 7m. Click for more nitrogen, phosphorus and potassium application techniques Click for more fertilizer application techniques