010-8 Wyo. Code R. § 8-40
(a) If not provided with an air gap as specified under Chapter 8, Section 41, a dual check valve with an intermediate vent preceded by a screen of not less than 100 mesh to 1 inch (25.4mm) shall be installed upstream from a carbonating device and downstream from any copper in the water supply line.
(b) A dual check valve attached to the carbonator need not be of the vented type if an air gap or vented backflow prevention device has been otherwise provided as specified under Chapter 8, Section 40(a).
(c) A plumbing system shall be installed to preclude backflow of a solid, liquid, or gas contaminant into the water supply system at each point of use at the establishment or processing plant, including on a hose bibb if a hose is attached or on a hose bibb if a hose is not attached and backflow prevention is required by the regulatory authority, by:
010-8 Wyo. Code R. § 8-40