Technical Skills & Application Flashcards

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?

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.

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?

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.

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?

Answer: 15

Total rise = 105 inches; 105 ÷ 7 = exactly 15 risers, which meets the maximum 7-inch riser height requirement.

In refrigeration, what condition does a very high superheat reading at the evaporator outlet typically indicate?

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.

Which property of a cutting tool material is most critical for high-speed dry machining of hardened steel?

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.

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?

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.

What is the primary reason for using a sacrificial anode in a hot water storage tank?

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.