Globe Valve vs Control Valve
A globe valve is a manual throttling valve with a linear-motion disc. A control valve is an automated throttling device (often globe-bodied) operated by a pneumatic, electric, or hydraulic actuator that receives signals from a process controller. The distinction is between manual and automated flow regulation.
Definition
A manual globe valve is operated by a handwheel. The operator adjusts the disc position to regulate flow. There is no feedback loop; the operator sets it and leaves it. A control valve is connected to a distributed control system (DCS) or programmable logic controller (PLC). It receives a 4-20 mA or digital signal that commands the actuator to position the trim at a specific opening, continuously adjusting to maintain a process variable (pressure, flow, temperature, or level).
When Used
Manual globe valve: bypass lines around control stations, manual throttling of cooling water, steam pressure reduction where load is relatively constant, and startup/shutdown flow adjustment. Standards: API 623, BS 1873.
Control valve: automated process control loops, continuous flow regulation, pressure letdown stations, and any application where the process variable must be held within tight tolerances. Standards: IEC 60534, ISA 75.
Specs Table
| Parameter | Manual Globe Valve | Control Valve |
|---|---|---|
| Operation | Handwheel (manual) | Actuator (pneumatic, electric, hydraulic) |
| Signal input | None | 4-20 mA, HART, Fieldbus, digital |
| Feedback | None (visual position indicator) | Positioner provides closed-loop feedback |
| Trim design | Standard disc and seat | Characterized plug (linear, equal-percentage, quick-open) |
| Cv calculation | Not typically sized by Cv | Sized precisely by Cv per ISA/IEC 60534 |
| Noise control | None | Multi-stage trim, cage-guided, diffuser trim |
| Cavitation control | None | Anti-cavitation trim (multi-stage pressure reduction) |
| Flow characteristic | Undefined (depends on disc shape) | Defined: linear, equal-percentage, quick-opening |
| Response time | Seconds to minutes (manual) | Milliseconds to seconds (actuated) |
| Cost | Lower (no actuator or positioner) | 3-10x globe valve cost |
| Standards | API 623, BS 1873 | IEC 60534, ISA 75 |
| Body types | Globe (straight, angle, Y) | Globe, butterfly, ball, rotary plug |
Comparison
The body of a control valve is often a globe valve body. The key difference is the precision trim, actuator, and positioner that transform it from a manual device into an automated control element. A control valve’s plug is machined with a specific flow characteristic (linear, equal-percentage) to provide predictable flow response across the operating range.
Manual globe valves are suitable where the flow setpoint rarely changes, the process is non-critical, and the cost of an automated valve cannot be justified. Control valves are required where process conditions change continuously and the control system must maintain precise regulation.
For valve body material specifications, see the guide to valve materials.
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