1. Floating ball valve
Structural principle: The ball can be displaced along the flow direction of the medium. When closed, the fluid pressure pushes the ball to press the outlet valve seat to achieve sealing.
Advantages: Simple and compact structure, excellent sealing (outstanding performance under low pressure conditions).
Limitations: The working medium load is concentrated on the outlet sealing ring, and the pressure resistance of the sealing material needs to be strictly controlled.
Applicable scenarios: Medium and low pressure clean medium systems with DN≤250mm and pressure≤PN40 (such as water treatment, low pressure gas).
2. Trunnion ball valve
Structural principle: The ball is fixed by upper and lower bearings, and the medium pressure drives the floating valve seat to press against the ball to form a seal; the high-pressure and large-diameter models are equipped with a lubricating oil film to reduce friction.
Advantages: Small operating torque, high pressure resistance (≥Class 300), and strong anti-scouring performance.
Limitations: Complex structure and higher cost than floating ball valve.
Applicable scenarios: high-pressure pipelines (long-distance oil pipelines), large diameters (DN＞250mm) and media containing trace particles.
3. Elastic ball valve
Structural principle: The ball has an elastic groove, and the wedge-shaped head of the valve stem opens the ball and presses the valve seat to seal (closed state). After release, the ball rebounds to reduce friction.
Advantages: Stable sealing under high temperature and high pressure, low opening and closing torque, and excellent wear resistance.
Limitations: The elastic groove design increases the process complexity.
Applicable scenarios: high-temperature steam (＞120℃), highly corrosive media and frequent opening and closing conditions.