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chapter 3
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Page 1
Indicate whether the statement is true or false.
1. An air separator should be located at the point in the system where fluid temperatures are lowest.
a.
True
b.
False
2. A hydronic system in which fluid is exposed to the atmosphere is an open-loop system.
a.
True
b.
False
3. The vapor pressure of a liquid is independent of temperature.
a.
True
b.
False
4. The specific heat of water is high in comparison with other common materials.
a.
True
b.
False
5. Water expands when it is heated.
a.
True
b.
False
Indicate the answer choice that best completes the statement or answers the question.
6. What is meant by equivalent length of a valve or fitting?
a.
its physical length at its longest dimension
b.
the length of a pipe that would produce the same head loss
c.
the length of a standard valve or fitting of the same material
d.
the length of the moving component in the valve
7. Why is a make-up water system necessary in a closed-loop hydronic system?
a.
A break in a line may occur at any time.
b.
The system must not be subject to unintended pressure changes.
c.
Fluid is designed to be expelled from the system at regular intervals.
d.
Small fluid losses will occur over time.
8. How does water’s flow velocity vary across a pipe’s diameter?
a.
remains constant across the diameter
b.
faster near the center of the pipe, and slower near the edges
c.
slower near the center of the pipe, and faster near the edges
d.
slower near the top surface, gradually increasing toward the bottom surface
9. How much energy is needed from the circulator in a closed-loop hydronic system?
a.
It depends on the elevation of the system.
b.
It depends on the weight of the fluid.
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c.
Enough is needed to sustain a flow rate of 2 to 4 gallons per minute.
d.
Enough is needed to replace the energy of head loss.
10. What is designed to accommodate water’s increase in volume in a closed-loop hydronic system?
a.
3-way mixing valve
b.
pressure gauge
c.
expansion tank
d.
backflow preventer
11. What is the best way to describe the compressibility of most liquids and gases?
a.
Liquids are compressible and gases are incompressible.
b.
Liquids and gases are incompressible.
c.
Liquids are incompressible; gases are compressible.
d.
A fluid’s compressibility depends on its specific heat.
12. What is static pressure?
a.
the pressure a fluid gains as it moves through a system
b.
the pressure due to the liquid’s own weight
c.
the pressure that does not change with a change in temperature in a closed system
d.
the pressure lost due to viscosity
13. What is the relationship between head energy and pressure in a closed-loop hydronic system?
a.
When head is lost, pressure increases.
b.
When head is gained, pressure increases.
c.
Both remain relatively constant.
d.
When head is lost, temperature increases.
14. In a system controlled by a high-limit controller, what is sometimes used to blend cool water returning from the heat
emitters with heated water from the heat source?
a.
3-way pressure valve
b.
3-way mixing valve
c.
pressure relief valve
d.
make-up water system
15. How is total head calculated?
a.
velocity head subtracted from the viscous head loss
b.
equal to the amount of elevation head
c.
sum of velocity head, kinetic head, and static pressure
d.
sum of velocity head, elevation head, and pressure head
16. What term best describes the heat absorbed or released by a material while it remains in a single phase?
a.
sensible heat
b.
latent heat
c.
single-phase heat
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d.
head
17. What term best describes the change in density of a system fluid?
a.
head
b.
latent heat
c.
stratification
d.
coalescence
18. What quantity is measured in psia?
a.
sensible heat
b.
absolute density
c.
absolute pressure
d.
active pressure
19. What are the primary factors that determine the amount of air that can exist in a solution of water?
a.
temperature and pressure
b.
temperature and volume
c.
pressure and type of dissolved gas
d.
type of fluid and type of dissolved gas
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chapter 3
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Page 4
Answer Key
