For a centrifugal pump, the ratio h1/h2 is designated as the _____________ efficiency (where h1 = measured actual head, h2 = head imparted by the impeller)?
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Answer: A. Mechanical
Explanation
Mechanical efficiency evaluates internal frictional losses in bearings, seals, and stuffing boxes. It is defined as the ratio of actual delivered pump head to the theoretical head imparted by the impeller. This efficiency accounts for mechanical power losses that occur outside the fluid flow path. Centrifugal pump efficiency is subdivided into mechanical, volumetric, and hydraulic efficiencies. Measured actual head reflects energy successfully transmitted to the fluid minus mechanical losses. Impeller head represents the theoretical energy added to fluid by rotating centrifugal vanes.
Pump manufacturers test equipment performance to verify mechanical efficiency ratings for buyers. Regular maintenance of pump bearings and mechanical seals prevents unnecessary mechanical efficiency drops. Industrial plant operators monitor pump power draw to detect internal mechanical binding or friction. Overall efficiency combines mechanical, hydraulic, and volumetric efficiencies into a single metric. Volumetric efficiency accounts for internal fluid leakage past wear rings and casing clearances. Impeller efficiency describes specific vane hydrodynamic performance rather than overall mechanical losses.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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