Abstract: An enclosure for a fluid flow control device of the type comprising a first valve positioned substantially vertically in a fluid flow pipe and a second valve positioned horizontally in a fluid flow pipe to form a compact backflow prevention device configuration. The enclosure comprises a front wall panel, a back wall panel, at least one removable side access panel and a top panel hingedly attached to the front wall and the back wall to open from a side of the enclosure for enabling unrestricted access to the components of the fluid flow control device contained therein. The enclosure includes at least one lift support device operably attached to the top panel and one of the wall panels to retain the top in an upright position when the top is opened to enable full access to the fluid flow control device. Locking devices are provided to prevent unauthorized access to the enclosure through the top panel and the at least one side access panel.