Generally applied to vertical electrostatic oiler lines for tin-plating and aluminum strip cover oiling, the oiler typically operates only below 8 mg/m² due to its low oiling volume of 2-12.5 mg/m². Excessive oiling can directly affect the end user's process, resulting in losses for the user. Therefore, how to effectively measure the oiling volume of the vertical oiler has always been a concern on site.

　　Due to its ultra-low oil coating amount, it is impossible to accurately determine the actual oil coating amount through visual inspection or conventional weighing methods. Below, we introduce a commonly used and accurate weighing instrument: the hydrophilic balance.

　　The D.O.S oil and C.S.O oil used for tinplate, aluminum strip, etc., due to their polar base, spread out on the water surface into a certain amount of monomolecular film. The SOM-A type oil coating amount tester utilizes this characteristic of the oil to transfer the oil on the surface of tinplate and aluminum strip onto a clean water surface. By measuring the area of the monomolecular film of the oil, the oil coating amount is determined. (See the figure below)