Are there any requirements regarding the purity of nitrogen used for nitrogen sealing in gasoline and diesel storage tanks?

\"Technical Guidelines for Light Oil Storage Tanks\" 6.4.2 Commissioning 1 Before commissioning a storage tank, it is advisable to first purge it with nitrogen; the oxygen content inside the tank should be less than 8% (v/v) to be considered acceptable. 2 For tanks that are to be sealed with nitrogen, the nitrogen sealing system must be activated first until the oxygen level inside the tank meets the required standards. 3 In cases of operational fluctuations such as startup and shutdown of production units or accident handling, the oil from the distillation outlet should not be directly fed into the storage tanks that are ready for use. 4 For the first time that oil is filled into a tank, it should be pumped in slowly from a tank of the same type, if conditions permit; the oil inflow rate should not exceed 1.0 m/s, until a very low liquid level is reached. 5 When the liquid level reaches the very low level, the flow velocity in the oil feed pipeline should not exceed 1.0 m/s. 6 Once the liquid level in the storage tank exceeds the very low level, the oil collection method can be adjusted according to actual production conditions, provided that the flow rate in the oil collection pipeline does not exceed 4.0 m/s. 7 Contact the instrument maintenance personnel to adjust the oil tank level gauges and thermometers for low and high levels respectively in a timely manner, to ensure their proper functioning. 8 Monitor the temperature indicators of the storage tanks, and take timely action if any values exceed the specified limits. Here, the oxygen content in the storage tank is required to be above 8%, so the purity of nitrogen needs to be over 93%. At our company, a level of less than 5% is considered acceptable, with a nitrogen purity of over 99% required

Isn’t it inappropriate to work backwards like this? I saw a document stating 99.96