DFF air volume measurement device is based on the back-to-back measurement principle: the measurement device is installed on the pipe, Its probe is inserted into the tube, When there is an air flow in the tube, Against the wind side, The kinetic energy of the airflow is converted into pressure energy, So the pressure in the face tube is higher, Its pressure is called "full pressure", The leeward side is not subject to airflow stamping, The pressure in the pipe is the static pressure in the air duct, Its pressure is called the "static pressure", The difference between full pressure and static pressure is called the differential pressure, Its size is related to the pipe wind speed (quantity), The greater the wind speed (volume), Greater the differential pressure: less wind speed (quantity), The differential pressure is also small, therefore, Just measuring the size of the trip pressure, Then find the corresponding relationship between travel pressure and wind speed (quantity), You can correctly measure the air volume in the pipe. Because the primary and secondary air volume and pulverizing air duct section is relatively large, for the wind volume measurement, only one measurement point is not enough, in order to be able to accurately measure the boiler primary and secondary air volume and pulverizing ventilation, we use the method is to use the same section on the section of the gale. According to the above measurement principle, according to the size of the measuring section size, the length of the straight section and other factors to determine the measuring points, many measuring points such as organically assembled together, positive pressure side and positive pressure side, negative pressure side and connected with negative pressure side, positive and negative pressure side each lead a total lead tube, respectively with the differential pressure transmitter of positive and negative end, measure the average speed of the section, and then calculate the air volume. Practice has proved that the device can be used reliably for a long time and become a maintenance-free product.