These Stainless Steel butterfly valves provide a low-cost alternative to bellows sealed gate valves. These valves easily actuate from the fully-closed position to fully open with only a quarter turn of the knob. A patented design allows the sealing disk to center itself when closing, with even pressure around the Viton O-ring seal. This design also helps to lower the amount of scuffing or rolling of the O-ring. Quarter-turn actuation, small footprint and the shortest possible gas path make our manual Butterfly Valves the preferred choice for many applications.