The ADACONN^® ACO Unified Series flange adapter is provided with an integral check valve. This combination allows one to easily provide check and fixed orifice flow control at a flange port, and terminate into a male thread. Check function may be placed on a manifold or actuator rather than within, resulting in a decrease in manifold size, or elimination of a special cartridge body. Such an approach lessens the need for machining cartridge cavities (with their associated special tooling) and cross drilling. In-line flow reduces pressure drop and wasted horsepower. Steel construction allows for use in systems up to 5000 psi. Valve orientation is reversible as required by the application. A variety of male threaded connections are available.