Immersion responsive sensor

Claim 1

Apparatus responsive to immersion in water in an open environment to complete an electrical circuit through which a signalling means is energized from an electrical energy source, said immersion responsive apparatus comprising latchable means responsive to completion of said circuit for latching said signalling means in an energized condition, a housing for said signalling means, a first inner electrically conductive element protruding from said housing and a second outer element protruding from said housing and substantially peripherally surrounding said first inner element to form a circumferential electrical shield for said first inner element to prevent said latchable means from latching in response to interference transients, said electrical shield having an opening at an end thereof opposite from said housing for enabling water to enter therethrough upon immersion, said outer electrical shield comprising an electrically conductive element which comprises a ground element for said circuit and an outermost non-conductive element surrounding said outer shield conductive element, said water completing said circuit between said electrically conductive elements in response to said immersion, said first and second elements being coextensive with said first element extent being less than said second element extent by a sufficient amount to prevent inadvertent electrically conductive contact with said first element prior to said immersion, said outer circumferential electrical shield having an air passageway in said peripherally surrounding portion for enabling the venting of air from within the interior of said outer electrical shield element at substantially any depth of immersion of said first and second elements in water less than total immersion while preventing the inadvertent entry of splash water prior to said immersion, said air passageway extending substantially the full longitudinal extent of said outer electrical shield and extending through said elements comprising said outer shield element, whereby water may enter within said outer electrical shield element interior to contact said first element and complete said electrical circuit at immersion depths where the water pressure is normally insufficient to cause said entry without venting of air and false signalling due to interference transients is prevented.