ASF ASF Tools and Equipment Usage 2 — Questions and Answers
Question 1: Which type of wrench is preferred when tightening refrigerant line flare fittings to avoid over-tightening?
- Pipe wrench
- Torque wrench (Correct answer)
- Adjustable wrench
- Strap wrench
Correct answer: Torque wrench
A torque wrench allows the technician to apply the manufacturer-specified torque to flare fittings, preventing leaks from under-tightening or cracked fittings from over-tightening.
Question 2: What does an electronic leak detector primarily sense when checking a refrigeration system?
- Pressure drops in the system
- Trace amounts of refrigerant gas in the air (Correct answer)
- Oil contamination in the refrigerant
- Moisture in the system
Correct answer: Trace amounts of refrigerant gas in the air
An electronic leak detector uses a heated diode or infrared sensor to detect trace concentrations of refrigerant vapor escaping from fittings, joints, or coils.
Question 3: Which tool would a technician use to cut copper refrigerant tubing cleanly without creating metal shavings inside the line?
- Hacksaw
- Pipe cutter (tubing cutter) (Correct answer)
- Angle grinder
- Aviation snips
Correct answer: Pipe cutter (tubing cutter)
A tubing cutter uses a hardened wheel to score and shear copper tubing cleanly, minimizing burrs and keeping metal debris out of the refrigerant circuit.
Question 4: What is the purpose of a nitrogen purge when brazing refrigerant lines?
- To cool the joint faster after brazing
- To prevent internal oxidation and scale formation inside the tubing (Correct answer)
- To pressurize the system for leak testing during brazing
- To clean flux residue from the joint
Correct answer: To prevent internal oxidation and scale formation inside the tubing
Flowing dry nitrogen through the tubing during brazing displaces oxygen, preventing copper oxide scale that could later contaminate compressor valves and metering devices.
Question 5: A micron gauge is used during refrigeration system service to verify what?
- Refrigerant charge weight
- Depth of vacuum achieved (Correct answer)
- Superheat at the evaporator
- Subcooling at the condenser
Correct answer: Depth of vacuum achieved
A micron gauge measures vacuum depth in microns of mercury, confirming the system has been evacuated deep enough (typically below 500 microns) to remove moisture and non-condensables.
Question 6: When should a technician replace the oil in a vacuum pump?
- Only when the pump stops running
- After each use or when the oil appears cloudy/dark (Correct answer)
- Every 5 years regardless of use
- Only when the vacuum depth drops below 100 microns
Correct answer: After each use or when the oil appears cloudy/dark
Vacuum pump oil absorbs moisture and contaminants during evacuation; cloudy or discolored oil loses its ability to achieve deep vacuums and should be replaced regularly.
ASF ASF Tools and Equipment Usage 2
Which type of wrench is preferred when tightening refrigerant line flare fittings to avoid over-tightening?