BELLOWS SEAL VALVE

PURPOSE:To prevent a bellows from breakage caused by drain accumulation and a valve from stick by mounting an auxiliary signal seal on a gland extending from the interior of the bellows of a valve spindle to the atmosphere to ventilate through a dehumidifying filter. CONSTITUTION:An air tight auxiliary gland seal 15 is provided on a valve spindle extending from the inside of an external pressure type bellows to the outside to prevent the valve spindle from intake off dew, rain, etc. thereon, while preventing the intrusion of the atmosphere containing a great amount of moisture with air tightness. A port 16 through which gas in the bellows enters and exists is provided to communicate to a tank 18 filled with dehumidifying agent 19 through a piping 17 for dehumidifying the atmosphere. The tank 18 has an opening 20 through which gas enters and exists, and air enters and exists according to the change in the inside volume of the bellows when a valve 22 is opened. Medium pressure acts on the inside of a bellows case 21 due to the medium leaking from a valve spindle bushing 8. Since pressure acts on the outside of the bellows, pressure resistance of the belllows is improved by about 1.5 times that the internal pressure type one. That is the intrusion of moisture and accidents are prevented.