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Control Valves
Throttling & Process Regulation Systems
Overview & Design
Control valves regulate pressure, flow rate, or temperature by dynamically adjusting the flow opening area in response to actuator signals.
Pedagogical Rationale
Processes must adapt to changing pressure demands, balance fluid proportions, and maintain system metrics under varying loads.
Standard Industry Applications
1Boiler steam feed regulation
2Chemical reactor ingredient proportioning
3Oil refinery distillation columns feed control
4Pipeline pressure reduction stations
Category Valve Types
Standard Globe Valve
Z-body path configuration with linear regulating plug.
Working Principle
The stem drives a contoured plug into a central seat ring. The fluid path shifts twice through the orifice, matching plug depth.
Advantages
Exceptional throttling precision
Short stem stroke path
Easy seat refurbishment
Limitations
High inherent pressure drop
Requires high actuator closing forces
Susceptible to cavitation damage
Needle Valve
Fine-tapered needle on a fine-pitch thread for precise low-flow metering.
Working Principle
Many turns of a fine-thread stem advance a slender tapered needle into a small seat orifice, changing the flow area in tiny increments for repeatable control.
Advantages
Very fine low-flow control
Compact high-pressure body
Metering plus positive shutoff
Limitations
Low flow capacity only
High pressure drop
Tip and seat damaged by particulates