Four-way switch valves

Features and benefits

• The sturdy one-piece ball and stem provides optimal strength, and is well suited to applications where fouling due to coke fines are a concern. The one-piece design avoids the problems generally associated with the more conventional two-piece ball and stem, which is highly susceptible to solids buildup in the ball-stem joint and a resulting increase in operating torques.Avoids hysteresis and misalignment.
• A Lantern ring with steam block and extra deep stuffing box minimizes the risk of leakage occurring through the packing chamber. Live-loading is available on request.
• Strong bellows offer a unique seat loading design that maintains the floating seats in constant contact with the ball and ensures a positive seal.
• Velan’s unique scraper type seats design scrapes coke buildup from the surface of the ball during each cycle. Seats are hard-faced to ensure a long, trouble-free service life. 
• Steam purges to bellows and body area ensure the valve cavities are kept free of coke buildup.
• The stem coupling is designed to perform three main functions:
  • Protect against “overtorquing” of the stem. 
  • Protect the actuator components. 
  • Protect against an unintentional switch into bypass (typically applies to four-way switch).