Manual operating means for valves

A manual operating means for the emergency and/or auxiliary operation of a normally electrically or pneumatically actuated valve, comprising a manual operating member which in a ready for use condition is so fixed at a housing recess in the valve in a sealing manner that its inner side faces the interior of the housing recess and its outer side is accessible for the application of a manual operating force, wherein the manual operating member is provided with venting means which, in order to avoid the establishment of excess pressure in the housing recess due to leakage, render possible the flow of air from the inner side to the outer side thereof and prevent the entry of nongaseous foreign matter in the opposite direction, wherein said venting means comprises a slot formed in said manual operating member, said slot including sealing faces in sealing contact with one another, said sealing faces being separable for opening said slot when there is an excess pressure on the inner side of said manual operating member.