5-10.
High-speed impellers must be
balanced to avoid vibration. What
is the purpose of a close radial
clearance between the outer hub
and the pump casing?
1.
To decrease friction
2.
To decrease axial thrust
3.
To minimize leakage from the
suction side
4.
To minimize leakage from the
discharge side
5-11.
What is the function of mechanical
seals and stuffing boxes?
1.
To improve pump operation
2.
To seal between the shaft and
the casing
3.
To clean bilges
4.
To prevent liquid from being
pumped
5-12.
What type of pump is considered to
be nonpositive displacement?
1.
Sliding vane
2.
Rotary
3.
Centrifugal
4.
Jet
5-13.
A pump that does not develop
enough discharge pressure could
have which of the following
problems?
1.
Clogged impeller passages
2.
A bent shaft
3.
Excessive suction lift
4.
Insufficient pump speed
5-14.
Which of the following statements
about a centrifugal pump is true?
1.
It is essentially self-priming
2.
It loses no energy
3.
It is a positive-displacement
pump
4.
It requires a relief valve
5-15.
What type of pump has no moving
parts?
1.
Screw
2.
Jet
3.
Gear
4.
Sliding vane
5-16.
What device uses feedback to
5-17.
5-18.
5-19.
5-20.
provide automatic control of
speed, pressure, or temperature?
1.
Regulating valve
2.
Flange coupling
3.
Proportional-flow filter
4.
Governor
What is the purpose of a valve in
a closed system?
1.
To sample fluids
2.
To control fluids
3.
To increase fluid pressure
4.
To decrease fluid pressure
Brass and bronze valves are never
used in systems that exceed what
maximum temperature?
1.
450°F
2.
550°F
3.
650°F
4.
750°F
There are many different types of
valves that can be used to control
fluid flow.
What are the two
basic groups of valves?
1.
Globe and check
2.
Check and gate
3.
Stop and check
4.
Gate and globe
Due to valve design, gate valves
are not used for throttling
purposes for which of the
following reasons?
1.
They make it difficult to
control fluid flow and can
damage valves
2.
They make it difficult to
control fluid flow and are too
lightweight
3.
They can damage valves and are
too lightweight
4.
They make it difficult to
control fluid flow and are
excessively expensive
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