a pneumatic seacock retrofit is provided for convenient closing of all or a portion of the seacocks , whether as a matter of every day convenience or for use in an emergency , in which all of the vessel &# 39 ; s seacocks can be pneumatically closed at the same time , leaving the possibility of selectively overriding seacock closure , with all control valves operating to provide a momentary pulse of air to the rotary actuators and then return to a neutral position , leaving the actuators free for further control . moreover , an operator is free to manually close a valve in the event that the pneumatic system fails .