FOX 3F is a full bore high quality single chamber double function combination air valve that evacuates air during pipeline filling, allows release of air pockets from pressurized pipelines, and admits large volume of air in the event of pipe draining or burst, to prevent vacuum and negative pressure conditions. Entirely made in ductile cast iron, with air release system and seat in stainless steel, Fox 3F stands out for its long lasting performances and reliability.