A 2-inch gate valve in a pipeline is substituted with an identical globe valve. If the initial gate valve pressure drop was Δp, what is the new pressure drop across the globe valve for the same volumetric discharge__________________?
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Answer: C. > Δp
Explanation
Globe valves feature a tortuous internal flow path that creates significantly higher fluid resistance than gate valves. Replacing a gate valve with a globe valve increases the overall pressure drop for the exact same volumetric discharge. This higher resistance makes globe valves suitable for flow throttling rather than full open low-loss service. Gate valves offer a straight-through flow path resulting in minimal pressure drop when fully open. Globe valves force the fluid to change direction multiple times around a plug and seat assembly. Valve resistance coefficients quantify the energy loss associated with different valve geometries and internal designs.
A pressure drop equal to delta p ignores the increased flow restriction introduced by the globe valve geometry. A pressure drop less than delta p incorrectly suggests that globe valves offer less resistance than gate valves. A pressure drop proportional to the square of delta p misrepresents standard valve flow characteristic equations.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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