View of the current existence of the conventional fume hood exhaust pipe closed strictly a result of smoke intrusion problem, active use of airtight device a means of mechanical and electrical integration, combined with position sensing technology and motor control circuit, real-time feedback channels in a closed state, and at the present electrical disc valve seal structure, based on the right wall and the disc plate to improve the structure, improving the tightness of the pipeline to extend the life of the elastic ring. Sealing device for existing structural weaknesses, the device sealing structure using eccentric structure, combined with flexible sealing technology to ensure complete sealing of the exhaust pipe, and through disc plate and the outer edge of ladder-like design of compacted ring fit and effective reduced seal wear and deformation, extending the life of seals.