Final answer:
Air-admittance valves are permitted to vent fixtures at island structures in kitchens.
Step-by-step explanation:
Air-admittance valves, also known as AAVs, are permitted to vent fixtures installed at island structures in kitchens.
An Air Admittance Valve (AAV), which you may also hear referred to as a Studor Vent, Studor AAV or Mini Vent, is a one-way mechanical valve that is installed locally at the site of a plumbing fixture, allowing proper venting to occur without a connection to a larger venting system and stack vent.
AAV's may be used in sanitary plumbing systems as trap vents, group vents, branch vents, some stack vents, and for the ventilation of branch drains. Drain where the combined length of the drain and fixture discharge pipe exceeds ten metres.
Air admittance valves shall not be used to vent sumps or tanks except where the vent system for the sump or tank has been designed by an engineer. Air admittance valves shall not be installed on outdoor vent terminals for the sole purpose of reducing clearances to gravity air intakes or mechanical air intakes.