Fluid filters

Claim 1

A FLUID FILTER COMPRISING, IN COMBINATION, A HEAD, A FILTER BOWL REMOVABLY ATTACHED TO SAID HEAD, A FILTER ELEMENT POSITIONED IN SAID BOWL, SAID FILTER ELEMENT AND SAID BOWL BEING LOCATED ALMOST ENTIRELY OUTSIDE OF SAID HEAD, A SUBSTANTIALLY CYLINDRICAL PRIMARY CHAMBER IN SAID HEAD, A COMMUNICATING PASSAGE BETWEEN SAID PRIMARY CHAMBER AND SAID FILTER BOWL LEADING TO THE OUTSIDE PORTION OF SAID FILTER ELEMENT, A FLUID INLET PORT IN THE HEAD COMMUNICATING WITH A FLUID INLET PASSAGE TO THE PRIMARY CHAMBER, SAID INLET PASSAGE ENTERING SAID CHAMBER TANGENTIALLY SO AS TO IMPART A ROTARY MOTION TO THE FLUID IN THE SAID CHAMBER, A CENTRALLY LOCATED FLUID OUTLET IN THE PRIMARY CHAMBER COAXIAL WITH SAID CHAMBER, THE ENTRANCE OF SAID FLUID OUTLET BEING LOCATED BETWEEN SAID FLUID INLET PASSAGE AND SAID COMMUNICATING PASSAGE TO SAID FILTER BOWL, FLUID PRESSURE RESPONSIVE MEANS FOR OPENING AND CLOSING SAID FLUID OUTLET IN THE PRIMARY CHAMBER IN RESPONSE TO PRESSURE DROP VARIATIONS ACROSS SAID FILTER ELEMENT, A FLUID OUTLET PORT FROM THE HEAD, A FLUID PASSAGE BETWEEN SAID COAXIAL OUTLET IN THE PRIMARY CHAMBER AND THE OUTLET PORT IN THE HEAD, AND A FLUID PASSAGE BETWEEN THE INSIDE PORTION OF THE FILTER ELEMENT AND THE OUTLET PORT ON THE HEAD.