CDC 3E151 - HVAC/R JOURNEYMAN VOLUME 1 EXAM QUESTIONS
WITH COMPLETE SOLUTIONS GRADED A+
(001) When using a halide leak detector, the bluish flame turning green indicates
a refrigerant leak
(001) On a manifold gauge assembly, the vacuum hose is 3/8 inch and the other
hoses are 1/4 inch because larger sizes allow for
fewer restrictions which makes it easier and quicker to pull a vacuum
(001) Why should the manifold gauge assembly not be used when measuring a
vacuum?
The gauge assembly reads inches of mercury and is not accurate when pulling deep
vacuums
(002) While taking a reading with an infrared thermometer, what happens as you
get further from the object being measured?
The reading becomes more inaccurate
(003) What part of the combustion analyzer gets placed into the stack?
The probe
(003) What transfers flue gases from the boiler stack to the indicator unit?
A tube and hand bulb
(003) The special slide-rule calculator and CO2 indicator are used to determine
combustion efficiency and stack loss
(004) What will occur if you choose more than one conductor to measure when
using a clamp on meter?
Incorrect readings
(004) A megohmmeter should never be used on a live circuit because
it has its own power source and it will ruin the meter
(004) A capacitance checker is used to test
a capacitor
(005) A photo tachometer is used to read the
revolutions per minute (RPM) of a spinning motor shaft
, (005) When using a stroboscope, the frequency and reading is displayed for the
technician when the object appears to be
standing still and the rpm of the equipment matches
(005) What pressure will be given if both tubes are connected to the inclined
manometer?
Velocity pressure
(005) Magnehelic pressure gauges were developed to
overcome the disadvantages of the inclined and the inclined vertical manometers
Why does the magnehelic gauge need more frequent calibration?
Because it is a mechanical instrument and is sensitive to physical abuse, dirt, dust,
corrosive gases, and fluids
(005) Why is the accuracy at filters, louvers, and coils very rough?
Due to the uncertainty of the Ak ( correction factor) area
(005) In order to be measured by the flow hood, how is all of the air forced to flow
through the diffuser or grille?
A flow hood or capture box completely surrounds and covers a diffuser or grille
(005) When are flow hoods especially practical?
In existing buildings where the manufacturers or Ak factors of the outlets are not known
(005) If you need a tool that functions as a balancing flowmeter you should select
a circuit tester
(006) When pipe is needed for a high pressure application you should select
extra strong pipe
(006) Pipe should not be threaded when it is
a wall thickness less than standard weight
(006) When would flanges be installed?
Wherever it may be necessary to open the joint for service or replacement of
components
(007) What must be done before you apply pressure on the dies?
Be sure you have the oil running to help start the segments on the pipe
(007) How are the die segments released?
Release lever
WITH COMPLETE SOLUTIONS GRADED A+
(001) When using a halide leak detector, the bluish flame turning green indicates
a refrigerant leak
(001) On a manifold gauge assembly, the vacuum hose is 3/8 inch and the other
hoses are 1/4 inch because larger sizes allow for
fewer restrictions which makes it easier and quicker to pull a vacuum
(001) Why should the manifold gauge assembly not be used when measuring a
vacuum?
The gauge assembly reads inches of mercury and is not accurate when pulling deep
vacuums
(002) While taking a reading with an infrared thermometer, what happens as you
get further from the object being measured?
The reading becomes more inaccurate
(003) What part of the combustion analyzer gets placed into the stack?
The probe
(003) What transfers flue gases from the boiler stack to the indicator unit?
A tube and hand bulb
(003) The special slide-rule calculator and CO2 indicator are used to determine
combustion efficiency and stack loss
(004) What will occur if you choose more than one conductor to measure when
using a clamp on meter?
Incorrect readings
(004) A megohmmeter should never be used on a live circuit because
it has its own power source and it will ruin the meter
(004) A capacitance checker is used to test
a capacitor
(005) A photo tachometer is used to read the
revolutions per minute (RPM) of a spinning motor shaft
, (005) When using a stroboscope, the frequency and reading is displayed for the
technician when the object appears to be
standing still and the rpm of the equipment matches
(005) What pressure will be given if both tubes are connected to the inclined
manometer?
Velocity pressure
(005) Magnehelic pressure gauges were developed to
overcome the disadvantages of the inclined and the inclined vertical manometers
Why does the magnehelic gauge need more frequent calibration?
Because it is a mechanical instrument and is sensitive to physical abuse, dirt, dust,
corrosive gases, and fluids
(005) Why is the accuracy at filters, louvers, and coils very rough?
Due to the uncertainty of the Ak ( correction factor) area
(005) In order to be measured by the flow hood, how is all of the air forced to flow
through the diffuser or grille?
A flow hood or capture box completely surrounds and covers a diffuser or grille
(005) When are flow hoods especially practical?
In existing buildings where the manufacturers or Ak factors of the outlets are not known
(005) If you need a tool that functions as a balancing flowmeter you should select
a circuit tester
(006) When pipe is needed for a high pressure application you should select
extra strong pipe
(006) Pipe should not be threaded when it is
a wall thickness less than standard weight
(006) When would flanges be installed?
Wherever it may be necessary to open the joint for service or replacement of
components
(007) What must be done before you apply pressure on the dies?
Be sure you have the oil running to help start the segments on the pipe
(007) How are the die segments released?
Release lever
