How to use a spirit level

The scale value of the level is expressed in degrees (seconds) or slopes, which means that the bubble is offset by the angle of a working inclined grid, or by the height of a working surface inclined grid over a length of one meter. Due to the small inclination angle of the level used, it is necessary to measure tg, such as tg4 with 4 radians=0.02mm/100mm, so that the working surface of the level is close to the measured surface, and only after the bubbles are stable can readings be taken. If it is necessary to measure the actual tilt value of length L, the following formula can be used for calculation. Actual tilt value=nominal division value L deviation grid number; For example, if the nominal scale value is 0.02mm/m, L=200mm, and the deviation grid number is 2, then the actual tilt value is 0.02/1000 * 200 * 2=0.008mm. To avoid measurement errors caused by inaccurate zero position of the level, it is necessary to check or adjust the zero position of the level before use.

The method of checking and adjusting the zero position of the level gauge is to place the level gauge to be calibrated on a roughly horizontal flat plate, close to the positioning block, wait for the bubble to stabilize, and then read a1 at one end of the bubble. Then, rotate the liquid level gauge 180 degrees to accurately place it in its original position. Record the reading of the other end a2 of the bubble based on the initial reading, and half of the difference between the two readings is the zero position error, which is equal to (a1-a2)/2 grid. If the zero position error exceeds the allowable range, the zero position mechanism needs to be adjusted, and this requirement can be met by repeatedly adjusting the screw.