Four-way switch valves
- Size range(s)
- NPS 3 - 18 (DN 80 - 450)
- Pressure rating
- ASME Classes 150 - 900
- Standard connections
Features and benefits
- 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.
- 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.
- Strong bellows offer a unique seat loading design that maintains the floating seats in constant contact with the ball and ensures a positive seal.
- Scraper type seats: Velan’s unique seat 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 electric, hydraulic or pneumatic actuator is selected in function of coker service. A large torque safety factor ensures the valve will cycle under the most stringent conditions. When selecting actuators, special attention is paid to the coker deck environment. The Stem Coupling is designed to perform 3 main functions: 1) Protect against ""overtorquing"" of the stem; 2) Protect the actuator components; 3) Protect against an unintentional switch.