Ball check-valve for linear reciprocating downhole pumps

The present disclosure relates to a ball check-valve assembly comprising a ball; a casing comprising an outer surface and defining an internal cavity extending within the casing, the internal cavity comprising a cylindrical inner wall; a bottom threaded connection at a downhole end of the casing, the bottom threaded connection comprising an opening therethrough to allow fluid passage into the internal cavity; a top threaded connection at an uphole end of the casing, at least three longitudinally extending guides defined within internal cylindrical cavity; and (f) a sealing surface formed in the casing and interposed between the top threaded connection and the internal cavity, the sealing surface further defining at least three quartic-shaped flow-passages extending from the sealing surface and providing for fluid passage through the sealing surface from the internal cavity to the uphole end of the casing.