(3) If the inlet and outlet holes of the solenoid pilot valve are blocked by oil sludge and other sundries, the sealing is not tight, the movable iron core is stuck, and the circuit is faulty, the electric butterfly valve can not reverse normally.

Low load regulating butterfly valve is simple in structure, small in size and light in weight. It is generally used in places with high temperature and low working pressure. The design structure of low load regulating butterfly valve has a great relationship with the operating conditions, and the specific structure shall be determined according to the operating conditions. From the use analysis, as a regulating control valve, as far as the main sealing structure is concerned, no matter the vertical plate or inclined plate structure, the general valve body structure with sealing ring is better than the diameter sealing structure without sealing ring. For smelting conditions, flue gas temperature is high and dust content is large, so inclined plate plane sealing structure is easy to be selected. The plane vertical plate sealing structure with sealing ring structure for valve body can be selected when the relative temperature and dust content under refining and chemical acid making conditions are low. For refining equipment with strict sealing requirements and high temperature conditions, lever type plane sealing structure is selected. For the shaft end structure of low load regulating butterfly valve, the combination external support structure is more reasonable. The main reasons affecting the normal opening and closing of the low load regulating butterfly valve are the thermal blockage, pipe wall dust adhesion and pipe ash blockage caused by the temperature change of the low load regulating butterfly valve during operation.