AIT Technical Skills & Application 4 — Questions and Answers
Question 1: A journeyman sheet metal worker is laying out a flat pattern for a 90-degree elbow. The K-factor in bend allowance calculations represents what?
- The yield strength of the sheet metal divided by its thickness
- The ratio that locates the neutral axis position within the metal thickness (Correct answer)
- The springback angle after the bend is released
- The die-to-punch clearance ratio
Correct answer: The ratio that locates the neutral axis position within the metal thickness
The K-factor is a ratio (typically 0.25–0.50) that defines where the neutral axis lies within the material thickness, which determines how much metal is consumed in the bend.
Question 2: When testing an electrical circuit with a clamp-on ammeter, what is the correct procedure for measuring current in a two-wire (line and neutral) cable?
- Clamp around both wires together to read total current
- Clamp around only one conductor — either the hot or the neutral (Correct answer)
- Clamp around the ground wire only to measure leakage
- Split the cable and clamp around the insulation junction point
Correct answer: Clamp around only one conductor — either the hot or the neutral
Clamping around only one conductor measures the current in that conductor; clamping both simultaneously causes the fields to cancel and reads near zero.
Question 3: A construction carpenter is calculating the rise and run for a staircase. If the total rise is 8 feet 9 inches and the maximum riser height per IBC is 7 inches, what is the minimum number of risers required?
- 14
- 15 (Correct answer)
- 16
- 17
Correct answer: 15
Total rise = 105 inches; 105 ÷ 7 = exactly 15 risers, which meets the maximum 7-inch riser height requirement.
Question 4: In refrigeration, what condition does a very high superheat reading at the evaporator outlet typically indicate?
- Refrigerant overcharge in the system
- A restriction in the liquid line or insufficient refrigerant flow through the metering device (Correct answer)
- A failed condenser fan motor
- High subcooling at the liquid line
Correct answer: A restriction in the liquid line or insufficient refrigerant flow through the metering device
High superheat means refrigerant boiled off early in the evaporator with a long dry section, indicating starvation from low refrigerant charge, a restricted liquid line, or an under-feeding TXV.
Question 5: Which property of a cutting tool material is most critical for high-speed dry machining of hardened steel?
- High toughness and impact resistance
- Hot hardness — the ability to retain hardness at elevated cutting temperatures (Correct answer)
- High thermal conductivity to dissipate heat into the workpiece
- Low coefficient of friction against steel only at room temperature
Correct answer: Hot hardness — the ability to retain hardness at elevated cutting temperatures
During high-speed dry cutting, tool tip temperatures can exceed 1000°F; hot hardness (retained hardness at temperature) is the critical property that prevents rapid tool wear.
Question 6: A plumber is installing a water supply system and must prevent backflow from a garden hose that is submerged in a chemical solution. Which backflow prevention device is required?
- Pressure vacuum breaker (PVB)
- Double check valve assembly (DCVA)
- Reduced pressure zone (RPZ) backflow preventer (Correct answer)
- Atmospheric vacuum breaker (AVB)
Correct answer: Reduced pressure zone (RPZ) backflow preventer
A submerged hose in a chemical creates a high-hazard cross-connection; an RPZ device is required because it provides the highest level of backflow protection and operates under continuous pressure.
Question 7: What is the primary reason for using a sacrificial anode in a hot water storage tank?
- To add minerals to improve water taste
- To act as a cathodic protection device that corrodes preferentially to protect the steel tank (Correct answer)
- To filter sediment from incoming water
- To regulate water temperature by absorbing excess heat
Correct answer: To act as a cathodic protection device that corrodes preferentially to protect the steel tank
The sacrificial anode (typically magnesium or aluminum) is more electrochemically active than the steel tank; it corrodes preferentially through galvanic action, protecting the tank from rust.
AIT Technical Skills & Application 4
A journeyman sheet metal worker is laying out a flat pattern for a 90-degree elbow.
The K-factor in bend allowance calculations represents what?