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3A2 > Chapter 12: Instrument and Control Devices > Flashcards

Chapter 12: Instrument and Control Devices Flashcards

1
Q

Bimetallic thermometers consist of two thin metal strips bonded together. The metal strips must have:
Select one:

a.
A difference in coefficient of elongation

b.
A difference in coefficient of expansion

c.
No difference in coefficient of expansion

d.
Equal coefficients of linear expansion

e.
Equal coefficients of volumetric expansion

A

b.
A difference in coefficient of expansion

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2
Q

Bimetal thermometers are sometimes wound in the form of a helix to:
Select one:

a.
Increase the distance of the scale

b.
Decrease the temperature range

c.
Decrease the rotation of pointer

d.
Increase the accuracy of temperature reading

e.
Increase the range of the scale

A

d.
Increase the accuracy of temperature reading

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3
Q

The orifice plate has the advantage over other types of metering restrictions because it:
Select one:

a.
Produces less permanent pressure drop

b.
Handles 60% more flow

c.
Is easy to install and replace

d.
More efficient than the other types

e.
Is permanently attached to the piping

A

c.
Is easy to install and replace

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4
Q

An absolute pressure gauge uses a/an _____ to sense the pressure.
Select one:

a.
Diaphragm under vacuum

b.
Bellows under vacuum

c.
Bourdon tube under vacuum

d.
Spiral Bourdon tube under vacuum

e.
Orifice plate

A

b.
Bellows under vacuum

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5
Q

The vena contracta is the point in the vicinity of an orifice plate where the:
Select one:

a.
Velocity is the lowest

b.
Fluid has the smallest cross-sectional area

c.
Pressure begins to decrease

d.
High-pressure connection is made

e.
Pressure is converted to velocity

A

b.
Fluid has the smallest cross-sectional area

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6
Q

Increasing the number of corrugations in a bellows type element:
Select one:

a.
Increases the travel of the bellows

b.
Decreases the travel of the bellows

c.
Reduces the pressure that bellows can be exposed to

d.
Increases the pressure that bellows can be exposed to

e.
Does not change the operation of the bellow

A

a.
Increases the travel of the bellows

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7
Q

The optical pyrometer operates on the principle that the colour of a hot object is a measure of its:
Select one:

a.
Size

b.
Mass

c.
Volume

d.
Specific heat

e.
Temperature

A

e.
Temperature

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8
Q

The most common form of flow measurement uses a(n) _____ to form a restriction.
Select one:

a.
Flow nozzle

b.
Venturi tube

c.
Orifice plate

d.
Pitot tube

e.
Square root extractor

A

c.
Orifice plate

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9
Q

In a venturi tube, the lowest pressure is found:
Select one:

a.
Three pipe diameters before the inlet

b.
In the outlet or divergent section

c.
In the inlet just before the converging section

d.
Three pipe diameters after the exit of the meter

e.
In the throat section

A

e.
In the throat section

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10
Q

A Bourdon tube has an oval cross-section, which is often shaped in the form of a “C,” and has an arc span of about:
Select one:

a.
90 degrees

b.
120 degrees

c.
180 degrees

d.
270 degrees

e.
360 degrees

A

d.
270 degrees

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11
Q

Venturi tubes are _______ efficient than an orifice plate with the same pipe size in terms of pressure recovery downstream of the constriction.

Select one:

a.
Considerably less

b.
Less

c.
Equally

d.
More

A

d.
More

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12
Q

A continuous air supply is provided to a differential pressure transmitter so that the _____ of liquid in a tank can be converted into a constant proportional air signal.
Select one:

a.
Level

b.
Mass

c.
Volume

d.
Temperature

e.
Viscosity

A

a.
Level

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13
Q

An undesirable feature of the orifice plate is _____.
Select one:

a.
The low permanent velocity loss

b.
The permanent pressure loss downstream

c.
Inability to change orifice sizes

d.
Difficult installation and replacement

e.
Only a full circular orifice may be used

A

b.
The permanent pressure loss downstream

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14
Q

Optical pyrometers are used:
Select one:

a.
To view flame in the boiler

b.
On oil-fired boilers only

c.
To measure temperature

d.
To protect the eyes when viewing a flame

e.
To measure the temperature of steam

A

c.
To measure temperature

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15
Q

The pressure differential across an orifice plate is measured by a _____ connection before the plate and a _____ connection after the plate.
Select one:

a.
High-pressure, low-pressure

b.
Low-pressure, high-pressure

c.
Low-pressure, low-pressure

d.
High-pressure, high-pressure

e.
Negative-pressure, positive-pressure

A

a.
High-pressure, low-pressure

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16
Q

Iron and constantan can be used in a thermocouple to measure a temperature range of:
Select one:

a.
–210°C to 1200°C

b.
–270°C to 1370°C

c.
0°C to 1820°C

d.
–270°C to 400°C

e.
–260°C to 1480°C

A

a.
–210°C to 1200°C

17
Q

Bellows type elements are generally used to measure pressures below _____ kPa.
Select one:

a.
50

b.
150

c.
250

d.
350

e.
340

A

d.
350

18
Q

The coefficient of expansion of aluminum is _____ that of copper.
Select one:

a.
Equal to

b.
Three times

c.
One-half

d.
Less than

e.
More than

A

e.
More than

19
Q

The optical pyrometer operates on the principle that the colour of a hot object is a measure of its:
Select one:

a.
Size

b.
Mass

c.
Volume

d.
Specific heat

e.
Temperature

A

e.
Temperature

20
Q

In a venturi tube, the lowest pressure is found:
Select one:

a.
Three pipe diameters before the inlet

b.
In the outlet or divergent section

c.
In the inlet just before the converging section

d.
Three pipe diameters after the exit of the meter

e.
In the throat section

A

e.
In the throat section

21
Q

Iron and constantan can be used in a thermocouple to measure a temperature range of:
Select one:

a.
–210°C to 1200°C

b.
–270°C to 1370°C

c.
0°C to 1820°C

d.
–270°C to 400°C

e.
–260°C to 1480°C

A

a.
–210°C to 1200°C

22
Q

Increasing the number of corrugations in a bellows type element:
Select one:

a.
Increases the travel of the bellows

b.
Decreases the travel of the bellows

c.
Reduces the pressure that bellows can be exposed to

d.
Increases the pressure that bellows can be exposed to

e.
Does not change the operation of the bellow

A

a.
Increases the travel of the bellows

23
Q

The pressure differential across an orifice plate is measured by a _____ connection before the plate and a _____ connection after the plate.
Select one:

a.
High-pressure, low-pressure

b.
Low-pressure, high-pressure

c.
Low-pressure, low-pressure

d.
High-pressure, high-pressure

e.
Negative-pressure, positive-pressure

A

a.
High-pressure, low-pressure

24
Q

An absolute pressure gauge uses a/an _____ to sense the pressure.
Select one:

a.
Diaphragm under vacuum

b.
Bellows under vacuum

c.
Bourdon tube under vacuum

d.
Spiral Bourdon tube under vacuum

e.
Orifice plate

A

b.
Bellows under vacuum

25
Q

Optical pyrometers are used:
Select one:

a.
To view flame in the boiler

b.
On oil-fired boilers only

c.
To measure temperature

d.
To protect the eyes when viewing a flame

e.
To measure the temperature of steam

A

c.
To measure temperature

26
Q

A Bourdon tube has an oval cross-section, which is often shaped in the form of a “C,” and has an arc span of about:
Select one:

a.
90 degrees

b.
120 degrees

c.
180 degrees

d.
270 degrees

e.
360 degrees

A

d.
270 degrees

27
Q

Venturi tubes are _______ efficient than an orifice plate with the same pipe size in terms of pressure recovery downstream of the constriction.

Select one:

a.
Considerably less

b.
Less

c.
Equally

d.
More

A

d.
More

28
Q

The coefficient of expansion of aluminum is _____ that of copper.
Select one:

a.
Equal to

b.
Three times

c.
One-half

d.
Less than

e.
More than

A

e.
More than

29
Q

Bimetallic thermometers consist of two thin metal strips bonded together. The metal strips must have:
Select one:

a.
A difference in coefficient of elongation

b.
A difference in coefficient of expansion

c.
No difference in coefficient of expansion

d.
Equal coefficients of linear expansion

e.
Equal coefficients of volumetric expansion

A

b.
A difference in coefficient of expansion

30
Q

The orifice plate has the advantage over other types of metering restrictions because it:
Select one:

a.
Produces less permanent pressure drop

b.
Handles 60% more flow

c.
Is easy to install and replace

d.
More efficient than the other types

e.
Is permanently attached to the piping

A

c.
Is easy to install and replace

3A2 (17 decks)

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