Mechanical Systems & Equipment Flashcards

A centrifugal pump is operating in cavitation. Which symptom is MOST characteristic?

Answer: Rattling or crackling noise with erratic flow

Cavitation causes vapor bubbles to implode violently, producing a rattling noise and unstable flow.

What is the primary purpose of a mechanical seal in a rotating pump?

Answer: To prevent fluid leakage along the shaft

Mechanical seals use lapped mating faces to prevent process fluid from leaking along the pump shaft.

Which gear type is BEST suited for transmitting high torque between parallel shafts with low noise?

Answer: Helical gears

Helical gears have angled teeth that engage gradually, reducing noise and enabling higher torque transmission between parallel shafts.

The Net Positive Suction Head Required (NPSHr) for a pump is determined by:

Answer: The pump manufacturer based on impeller design

NPSHr is a pump characteristic established by the manufacturer through testing and is fixed for a given pump and flow rate.

A V-belt drive shows excessive slippage. The FIRST corrective action should be:

Answer: Check and adjust belt tension to specification

Insufficient tension is the most common cause of belt slippage, and adjusting tension to the manufacturer's specification corrects this before replacement is considered.

What does the "specific speed" of a centrifugal pump describe?

Answer: The pump's shape and performance characteristics

Specific speed is a dimensionless index that classifies pump impeller geometry and predicts performance behavior at the best efficiency point.

In a hydraulic system, a pressure relief valve is set above the normal working pressure to:

Answer: Protect system components from overpressure

The relief valve bypasses fluid back to the reservoir when system pressure exceeds the set point, protecting hoses, cylinders, and valves from damage.