The invention relates to the technical field of mechanical sealing board
plug valve, in particular to an air-tight board
plug valve which comprises a
valve seat, an upper valve cover, an upper valve cover hold-down bolt, a board plug, a board plug lock nut, a board plug push rod and a board plug push rod driving device; wherein, a
special section rubber sealing ring provided with a cavity is arranged between the upper valve cover and the board plug, the outer side of the
special section rubber sealing ring is contacted with the
valve seat, and the inner side is contacted with a chuck ring of the sealing ring; the cavity of the
special section rubber sealing ring is communicated with a venting cavity of the upper valve cover to form an air-tight cavity, and a compressed-air pipeline is connected with the venting cavity of the upper valve cover to charge the air-tight cavity. Sealing grooves are respectively arranged at the lower side of the upper valve cover, the upper end surface of the chuck ring of the sealing ring and the upper end surface of the
valve seat and matched with preiection of the special section rubber sealing ring, thus ensuring the board
plug valve to have good sealing structure. A
solid lubricant column is arranged between the valve seat and the board plug. The air-tight board plug valve has the advantages of good sealing performance, flexible and convenient operation and long service life.