Coupling with male half having internal pressure relief

Abstract

A coupling half comprising: a body; a principal valve seating against the body and unseating therefrom; a relief valve seating against the principal valve and unseating therefrom; and, a flush face sliding sleeve valve seating against the body and unseating therefrom is disclosed. When the flush face sliding sleeve valve unseats from the body it travels toward the relief valve and engages the relief valve unseating the relief valve from the principal valve permitting flow by the relief valve and enabling the principal valve to unseat from the body. The relief valve and the principal valve define an annulus therebetween. The principal valve includes a passageway for relieving pressure by the relief valve. As the relief valve unseats from the principal valve, flow is permitted to the annulus defined by the relief valve and the principal valve and through the passageway in the principal valve and to a reservoir generally defined by the principal valve and the body. This causes a reduction in pressure upstream of the principal valve which enables the principal valve to unseat from the body. A first balanced seal resides in a circumferential groove in the body of the coupling half and prevents the escape of fluid from the coupling half and a second balanced seal resides in a first circumferential groove of the principal valve and prevents intrusion of fluid into a volume generally bounded by the interior of the flush face sliding sleeve valve, and the exteriors of the relief valve and principal valve. The principal valve and the relief valve both include extensions which are threaded thereto.