What are the classifications of pneumatic ball valves
Aug 14, 2025
Classification by Structure: Core Design and Applications
Floating Ball Valve:
The ball floats slightly under fluid pressure; seat sealing relies on preloaded springs or fluid pressure.
Simple structure, low cost; suitable for low-pressure, small-bore (typically DN≤200mm) clean media (e.g., tap water, natural gas pipelines).
Prone to leakage under high pressure; requires periodic maintenance.
Trunnion-Mounted Ball Valve:
Ball fixed by upper/lower support shafts; seats use spring preload or floating design.
High sealing performance, pressure-resistant (up to PN6.3MPa); ideal for high-pressure applications (e.g., petroleum, chemical industries).
Complex structure and higher cost.
Three-Way Ball Valve:
Features L/T-shaped flow paths for fluid diversion, merging, or flow direction switching.
Widely used in pharmaceuticals/food processing requiring multi-line control.
Nominal diameter range: DN15–DN300 (per ISO 5211).
Classification by Function: Operational Objectives and Technical Features
On/Off Type:
Only fully opens/closes; fast response (<0.1 sec action time).
Used in emergency shut-off systems (e.g., firefighting pipelines).
Regulating Type:
Controls opening degree via pneumatic positioners for precise flow adjustment (accuracy: ±1% FS).
Applied in scenarios requiring continuous modulation (e.g., boiler temperature control).
Other Classification Dimensions: Materials and Special Designs
Material Classification:
Metal Hard Seals (stainless/carbon steel):
Heat-resistant (≤550°C), corrosion-resistant; suitable for steam/acidic media.
Soft Seals (PTFE, nylon):
For cryogenic (≥-196°C) and clean media; shorter lifespan (~50,000 cycles).
Special Designs:
V-Notch Ball Valve:
Ball with V-shaped groove for adjustable flow curves; used in pulp control for papermaking.
Fire-Safe Type:
Seats incorporate graphite or metal backup rings to maintain sealing during fires (compliant with API 607).
