Before using the level, we should first check its usability to see if there are defects such as cracks and air holes on the surface of the level, and if the liquid in the level is clean and transparent, etc. After making sure the level is intact and available, we have to calibrate it. The method of calibrating the level is very simple: put the level against the wall, draw a line along the edge of the ruler on the wall, and then swap the left and right ends of the level to the original drawn line, if the ruler and the line overlap, the water in the level tube of the level is still flat, it means that the level is accurate, and vice versa, it needs to be corrected.

The level ruler generally has three glass tubes, and each glass tube has a bubble. If the bubble is in the center, it means the measured object is horizontal in that direction. The horizontal glass tube is used to measure the horizontal surface, the vertical glass tube is used to measure the vertical surface, and the other one is used to measure the forty-five degree angle, and the three water bubbles are used to check whether the measuring surface is horizontal, and the water bubble is centered on the horizontal, and vice versa. In addition, according to the principle of two cross lines to determine a plane, it needs to be measured at two non-parallel positions in the same plane to determine the level of the plane.

The horizontal ruler is very easy to keep, hanging in a certain place or flat on the desktop, drawer can be, and will not affect its straightness and parallelism because of long-term flat. If it is the aluminum magnesium light level, there is not easy to rust the characteristics of oh. During the use period, the level ruler does not need to be coated with oil, if it is not used for a long time, it can be gently coated with a thin layer of general industrial oil when it is stored.