CDC 3E151 Vol 1 Questions with Correct Answers Latest Version 2025
1. What is most important when it comes to using leak detectors? - Answers Knowing how and when to
use each one.
2. If there is a large refrigerant leak, what type of readings may be obtained if using a halide leak
detector? - Answers False readings and prevents detection of small leaks.
3. Where should a halide leak detector be used? - Answers In well-ventilated spaces.
4. Since the fluorescent leak detector is good for finding larger leaks, what type of leaks could take
longer to find? - Answers Small leaks.
5. When using an ultrasonic leak detector, why does the type of refrigerant in the system not matter? -
Answers Because any turbulent gas will generate ultrasound when it leaks.
6. What does combining the ultrasonic leak detector with soapy bubbles will allow you to locate? -
Answers Very small leaks.
7. What usually causes problems with a gauge? - Answers Leaking or broken bourdon tube.
8. When would a compressor oil pump be used? - Answers For charging refrigeration compressors with
oil while they are under pressure.
9. Where does the first stage of a two-stage vacuum pump send its intake pressure? - Answers Exhausts
it to the intake of the second stage.
10. What allows a two-stage vacuum pump to pull a lower vacuum than a single-stage vacuum pump? -
Answers The second stage pulling in at a lower pressure.
11. Why should you not use the manifold gauge assembly when measuring a vacuum? - Answers The
gauge assembly reads inches of mercury and is not accurate when pulling deep vacuums.
12. How can micron gauges be connected? - Answers To the system's piping or the MGA connection.
1. What is the most basic type of thermometer? - Answers Glass stem mercury type.
2. Why should the probe on a dial type thermometer not be held while taking temperature readings? -
Answers This will affect the temperature reading.
3. How can the reading on an electronic thermometer be affected? - Answers Location.
4. When would a recording-type thermometer be used? - Answers To prove to a customer that a facility
or room is getting the proper temperatures. Also, it could be used to identify a troublesome area
5. On superheat/subcooling thermometers, how is the temperature converted to a digital display? -
Answers By a thermocouple.
, 1. What part of the combustion analyzer gets placed into the stack? - Answers Probe.
2. What will happen if the digital combustion analyzer is not properly cared for? - Answers Erroneous
readings.
3. In an absorption type analyzer, what combines with the gas being measured? - Answers Column of
liquid.
4. What are the special slide-rule calculator and CO2 indicator used to determine? - Answers
Combustion efficiency slide rule
5. When a rapid, simple means to determine combustion efficiency and stack is needed, what tool would
you use? - Answers To place the clamp on around a conductor and operate controls or observe other
parts of the system running on the other side of the mechanical room and still be able to read the amps
flowing through the conductor.
6. How would a technician measure the smoke content in the flue gases? - Answers A smoke tester.
7. How would a technician measure the draft in a system? - Answers With a draft gauge.
004. Electrical testing tools - Answers
1. What will happen if you do not turn off the meter when it is not in use? - Answers It will die sooner.
2. Why should you avoid dropping digital meters? - Answers Because you may damage the electronics
on the inside.
3. Why must you ensure no wires are exposed on your meter's leads? - Answers Bare leads can shock
you if you touch them.
4. If a meter is defective, what must be done? - Answers Replace it.
5. When could the wireless feature on a clamp on meter be used? - Answers To place the clamp on
around a conductor and operate controls or observe other parts of the system running on the other side
of the mechanical room and still be able to read the amps flowing through the conductor.
6. When would a megohmmeter be used? - Answers To measure the resistance of insulating material.
7. When would a green light appear on a voltage tester? - Answers When voltage is present.
8. When would an electrical tester be used? - Answers Because a quick voltage check is desired.
9. When would a capacitance checker be used? - Answers To test a capacitor.
005. Air and hydronic measurement tools - Answers
1. What may result if you do not exercise caution when using direct-contact manually timed revolution
counters? - Answers Injury.
1. What is most important when it comes to using leak detectors? - Answers Knowing how and when to
use each one.
2. If there is a large refrigerant leak, what type of readings may be obtained if using a halide leak
detector? - Answers False readings and prevents detection of small leaks.
3. Where should a halide leak detector be used? - Answers In well-ventilated spaces.
4. Since the fluorescent leak detector is good for finding larger leaks, what type of leaks could take
longer to find? - Answers Small leaks.
5. When using an ultrasonic leak detector, why does the type of refrigerant in the system not matter? -
Answers Because any turbulent gas will generate ultrasound when it leaks.
6. What does combining the ultrasonic leak detector with soapy bubbles will allow you to locate? -
Answers Very small leaks.
7. What usually causes problems with a gauge? - Answers Leaking or broken bourdon tube.
8. When would a compressor oil pump be used? - Answers For charging refrigeration compressors with
oil while they are under pressure.
9. Where does the first stage of a two-stage vacuum pump send its intake pressure? - Answers Exhausts
it to the intake of the second stage.
10. What allows a two-stage vacuum pump to pull a lower vacuum than a single-stage vacuum pump? -
Answers The second stage pulling in at a lower pressure.
11. Why should you not use the manifold gauge assembly when measuring a vacuum? - Answers The
gauge assembly reads inches of mercury and is not accurate when pulling deep vacuums.
12. How can micron gauges be connected? - Answers To the system's piping or the MGA connection.
1. What is the most basic type of thermometer? - Answers Glass stem mercury type.
2. Why should the probe on a dial type thermometer not be held while taking temperature readings? -
Answers This will affect the temperature reading.
3. How can the reading on an electronic thermometer be affected? - Answers Location.
4. When would a recording-type thermometer be used? - Answers To prove to a customer that a facility
or room is getting the proper temperatures. Also, it could be used to identify a troublesome area
5. On superheat/subcooling thermometers, how is the temperature converted to a digital display? -
Answers By a thermocouple.
, 1. What part of the combustion analyzer gets placed into the stack? - Answers Probe.
2. What will happen if the digital combustion analyzer is not properly cared for? - Answers Erroneous
readings.
3. In an absorption type analyzer, what combines with the gas being measured? - Answers Column of
liquid.
4. What are the special slide-rule calculator and CO2 indicator used to determine? - Answers
Combustion efficiency slide rule
5. When a rapid, simple means to determine combustion efficiency and stack is needed, what tool would
you use? - Answers To place the clamp on around a conductor and operate controls or observe other
parts of the system running on the other side of the mechanical room and still be able to read the amps
flowing through the conductor.
6. How would a technician measure the smoke content in the flue gases? - Answers A smoke tester.
7. How would a technician measure the draft in a system? - Answers With a draft gauge.
004. Electrical testing tools - Answers
1. What will happen if you do not turn off the meter when it is not in use? - Answers It will die sooner.
2. Why should you avoid dropping digital meters? - Answers Because you may damage the electronics
on the inside.
3. Why must you ensure no wires are exposed on your meter's leads? - Answers Bare leads can shock
you if you touch them.
4. If a meter is defective, what must be done? - Answers Replace it.
5. When could the wireless feature on a clamp on meter be used? - Answers To place the clamp on
around a conductor and operate controls or observe other parts of the system running on the other side
of the mechanical room and still be able to read the amps flowing through the conductor.
6. When would a megohmmeter be used? - Answers To measure the resistance of insulating material.
7. When would a green light appear on a voltage tester? - Answers When voltage is present.
8. When would an electrical tester be used? - Answers Because a quick voltage check is desired.
9. When would a capacitance checker be used? - Answers To test a capacitor.
005. Air and hydronic measurement tools - Answers
1. What may result if you do not exercise caution when using direct-contact manually timed revolution
counters? - Answers Injury.
