Provided, in one aspect, is a fluid flow device. The fluid flow device may include a housing having at least one fluid inlet and at least one fluid outlet. The fluid flow device according to this aspect may further include a flexible tube positioned within the housing, the flexible tube defining a fluid flow path, the flexible tube operable to have a first diameter (d1) when the flexible tube encounters a first pressure from fluid within the housing and a second different diameter (d2) when the flexible tube encounters a second greater pressure within the housing, the first diameter (d1) and second different diameter (d2) configured to provide a constant flow of the fluid out of the at least one fluid outlet.