Valtorc's trunnion mounted designed ball valves are a high strength and quality valve for your industrial needs. Offered in class 150/300/600/900 and 1500 in sizes from 2" - 12" in size. The series 300 valves are offered in flanged connection ends with Nylon and Peek seats. When the Ball Valve body cavity pressure exceeds the down stream seat spring preloaded force, the differential force in the cavity area pushes the downstream seat away from the ball, the body cavity pressure will automatically relived. And then seat returns to the ball under spring loaded action.