I. Isolation Valves
| Type | Operation Principle | Applications |
|---|---|---|
| Gate Valve | Flat wedge perpendicular to flow (low resistance) | Large-diameter pipelines (e.g., water mains) |
| Ball Valve | Rotating sphere with bore (quick shutoff) | Emergency gas line isolation |
| Butterfly Valve | Rotating disc (compact/lightweight) | HVAC water circulation |
| Plug Valve | Tapered rotating plug (corrosion-resistant) | Chemical aggressive media |
II. Control Valves
| Type | Control Method | Example Use |
|---|---|---|
| Globe Valve | Linear stem movement (throttling) | Steam system flow regulation |
| Needle Valve | Precision tapered needle (micro-flow) | Instrumentation pressure lines |
| Self-operated Regulator | Media-pressure actuated | Storage tank pressure stabilization |
III. Check Valves
Lift Check: Vertical disc movement (pump discharge)
Swing Check: Hinged disc rotation (wastewater systems)
Dual-Plate Wafer: Space-saving design for tight installations
IV. Safety Valves
Function: Pressure relief at setpoints (critical metrics: set pressure/reseat pressure)
Application: Boilers/PV equipment (spring-loaded variants)
V. Pressure Reducing Valves
Pilot-operated: High accuracy (lab gas lines)
Direct-acting: Rapid response (firewater systems)
VI. Steam Traps
| Type | Working Principle | Implementation |
|---|---|---|
| Mechanical | Float-controlled (main steam lines) | |
| Thermostatic | Temperature-sensitive element | Heat tracing pipes |
| Thermodynamic | Disc snap-action (fast drainage) |
VII. Specialty Valves
Blowdown Valves: Bottom-mounted debris removal (e.g., ball-type)
Air Release Valves: Automatic air expulsion (water supply networks)
Multi-function Valves: Combined shutoff/check/balancing (HVAC systems)
VIII. Selection Criteria
Media: Chemical compatibility (e.g., PTFE-lined for chlorine)
P/T Ratings: Chrome-molybdenum steel for high-temp steam
Cycle Frequency: Butterfly valves for frequent operation
Space Constraints: Vertical check valves for upright pipes
IX. Industry-Specific Practices
Oil & Gas: API-standard gate valves, high-pressure Y-pattern globes
Water Utilities: Rubber-seated butterfly valves, silent checks
Pharma: Sanitary diaphragm valves (CIP-compatible designs)
