Model CL - LL11 flow sensor uses the functional relationship between the mud flow rate and the baffle board, using the resistance changes of single coil regulation resistance to reflect the angular displacement change of the baffle board, to measure the relative changes of mud flow rate. To prevent alkali corrosion of the mud, the integral unit of the sensor adopts stainless steel material. Owing to the bad using condition at the well site, sealing design is adopted between the shaft of the sensor and the brass tube to prevent mud from entering. The conductive plastic single coil potentiometer has high precision, and its operating environment temperature range is wide; it has a long service life, very high reliability and resistance to chemical attack. The product has advantages of simple and convenient installation, compact structure, easy maintenance and safety explosion-proof; it is an important sensor used in petroleum drilling operations.