Check valve assembly

Claim 1

A check valve assembly for permitting unrestricted flow in one direction and limited flow in the reverse direction comprising: a. a valve body having a longitudinal flowbore therethrough comprising first and third concentric sections connected by a second concentric section of restricted diameter; b. seat means carried by said valve body at one end of said third flowbore section; c. a pair of discreet recesses in said valve body communicating with said flowbore near the junction of said second and third flowbore sections and inclined from said flowbore radially and longitudinally away from said third section; d. ball closure means for disposal in either one of said recesses and movable into said flowbore for sealing engagement with said seat means, in response to a predetermined rate of reverse flow through said check valve assembly, to block reverse flow of fluid through said check valve assembly; e. a pair of elongate equalizing passages each having one end communicating with said first flowbore section and another end communicating with a respective one of said recesses, each of said equalizing passages having at least a part thereof adjacent said one end which is radially and longitudinally inclined with respect to said first flowbore section and adapted to receive replaceable orifice means, and f. means preventing direct communication between said flowbore and a portion of each of said equalizing passages intermediate the ends of said equalizing passage.