GB/T 37918-2019 in English

Comparison of potassium oxide determination methods

Potassium tetraphenylborate gravimetric method is used as an arbitration method. It generates precipitation under alkaline conditions and has an accuracy of ±0.38%. Thermometry titration method utilizes the principle of exothermic reaction and is suitable for rapid batch detection. The standard solution needs to be calibrated regularly.

Physical performance requirements for granules

• Particle size control: Powdered products pass through a 1.00mm sieve, and more than 90% of granular products remain in the range of 2.00-4.75mm
• Compressive strength: The average crushing strength of granular products is ≥25N, ensuring the applicability of blended fertilizer production

Sampling specifications

When the batch size is ≤512 bags, the minimum sampling volume is determined according to Table 2, and when it is greater than 512 bags, it is calculated according to the formula (3×√N). The sample size of each batch is ≥2kg, and it must be sealed and stored after being reduced by the quartering method.

Labeling requirements

Product type, potassium oxide (dry basis) and moisture content must be marked compulsorily, and it is recommended to use a QR code to supplement the information. The net content should be marked with a single value (such as 50kg), in accordance with GB18382.