A self-acting pressure activated drain valve , comprising: a housing including an upper side , a lower side , and a rim between the upper side and the lower side , the upper side and the rim defining at least one inlet therebetween that is configured to receive a fluid; at least one outlet configured to expel the fluid; and a drainage passage surrounded by the housing and extending from the rim to the lower side , the drainage passage including a first opening in fluid communication with the at least one inlet and a second opening in fluid communication with the at least one outlet , the first opening interposed between the upper side and the second opening , ; and a flexible diaphragm supported at the upper side such that the at least one inlet is interposed between the rim and the flexible diaphragm , the flexible diaphragm configured to operate in an open position and a closed position based on a pressure, wherein the flexible diaphragm is normally biased in the open position such that fluid is delivered from the at least one inlet to the at least one outlet via the drainage passage , wherein the rim extends radially along a plane between the inlets and the first opening to direct fluid along a plurality of flow paths arranged about the circumference of the rim , wherein the drainage passage extends perpendicular with respect to the flow paths, wherein the diaphragm is configured to collapse into the drainage passage to seal the first opening when operating in the closed position to block the fluid, delivered into the housing via the flow paths, from traveling between the first opening and the second opening. a housing including an upper side , a lower side , and a rim between the upper side and the lower side , the upper side and the rim defining at least one inlet therebetween that is configured to receive a fluid; at least one outlet configured to expel the fluid; and a drainage passage surrounded by the housing and extending from the rim to the lower side , the drainage passage including a first opening in fluid communication with the at least one inlet and a second opening in fluid communication with the at least one outlet , the first opening interposed between the upper side and the second opening , ; and a flexible diaphragm supported at the upper side such that the at least one inlet is interposed between the rim and the flexible diaphragm , the flexible diaphragm configured to operate in an open position and a closed position based on a pressure, wherein the flexible diaphragm is normally biased in the open position such that fluid is delivered from the at least one inlet to the at least one outlet via the drainage passage , wherein the rim extends radially along a plane between the inlets and the first opening to direct fluid along a plurality of flow paths arranged about the circumference of the rim , wherein the drainage passage extends perpendicular with respect to the flow paths, wherein the diaphragm is configured to collapse into the drainage passage to seal the first opening when operating in the closed position to block the fluid, delivered into the housing via the flow paths, from traveling between the first opening and the second opening. <EOS>