In scientific research, production, teaching, environmental protection and clean rooms, mine ventilation, energy management, commonly used pitot tube to measure wind speed, pipe furnaces flue gas velocity, after conversion to determine the flow rate, measurement of flow velocity in the pipe. In order to measure the accuracy of the interpretation of the below using pitot some techniques and precautions: 1. To correctly choose measurement point section, to ensure the measuring point straight pipe in air flow smoothly. Therefore, measuring the cross section from the flow direction of the bend, variable diameter abnormity tube such as local components more than four times the pipe diameter. From the downstream direction of local bend, the structure of the variable diameter should be greater than 2 times the pipe diameter. 2. Pitot tube to measure the total pressure hole shall be on the airflow direction, to point to the pole. Measurement point insertion hole should avoid air leakage, and can prevent the airflow interference on the cross section. With pitot tube can only be measured on the pipeline section velocity of one point, because of the uneven distribution of cross section flow, so this section should be more measuring points, in order to calculate the average. 3. Before using the smooth general characteristic test. Small static pressure hole check, don't make the impurities clogging pores after use clean the tube inside and outside, to ensure the good condition for a long time.