Level instrument testing

Instrument inspection
The inspection of the spirit level must be carried out in accordance with the corresponding standards. The temperature in the inspection room should be 20±2℃, and the inspection should be carried out under the condition of being strong and free of vibration and away from heat sources. Before the inspection, the parts of the level must be scrubbed clean, and then the level is placed on the metal plate in the inspection room, the same temperature time shall not be less than 3h.
Visual inspection
For the newly manufactured spirit level, the working surface should be flat, smooth and free of defects such as blisters, pores, bruises, scratches, rust, etc. Paint stripping, rust and obvious defects are not allowed on the non-working surface. The level should be clean and transparent, its engraved line should be clear and uniform, and there should be no decolorization, and the engraved line should be perpendicular to the axis of the level. The non-working surface of the level should be marked with the manufacturer’s name, factory number and graduation value.
Interaction between parts
The main level should be installed firmly, and the zero-position adjustment device should be easy to use and reliable. The bubble movement should be stable, and there should be no visible jumping or stagnation. When the room temperature is 20℃, the length of the bubble should be equal to the distance between the two long scale lines, and the deviation should not exceed ±1 division for graduations of 0.02~0.05mm/m; for graduations of 0.06~0.10mm /m should not exceed ±0.5 divisions. The smoothness of the bubble movement and the length of the bubble should be tested on the level tester.
Flatness of working surface
The working surface of the level gauge is not allowed to have bulging phenomenon, and its flatness should meet the requirements of Table 6-10-54. Length of working surface 150~200 250~300, flatness deviation <0.003 <0.005, for the grinding and grinding working surface, the flatness shall be verified by the optical gap method with a zero-grade edge ruler whose size is not less than the length of the tested surface , This verification work should be carried out at several positions in the longitudinal, transverse and diagonal directions of the working face. Take the maximum gap seen as the flatness deviation of the surface. When estimating the gap size, the standard gap composed of gauge blocks can be compared.
For the flatness of the scraped working surface, the zero-level flat plate is used for verification by the coloring method. The number of spots in a square area with a side length of 25mm should not be less than 25 points for a level with a scale of 0.02~0.05mm/m, and not less than 20 for a level with a scale of 0.06~0.10mm/m Spots and spots should be evenly distributed.
The straightness of the V-shaped working surface is verified by the coloring method with the verification mandrel. Place the mandrel coated with red lead powder on the V-shaped surface and rotate. The contact line seen on the V-shaped surface is not allowed to have a discontinuity of more than 10mm.