Question 24 QMED05 - Machinist-Pump Technician

The Correct Answer is B. ### Why Option B ("non-ferrous") is correct: When working in an environment where explosive gases (like volatile hydrocarbons or solvents) may accumulate, the primary safety concern is preventing ignition sources. Using standard tools made of materials like high carbon steel (ferrous materials) can generate a spark if they strike another hard surface (such as steel beams, concrete, or other tools). This mechanical sparking phenomenon is caused by frictional heat or impact. **Non-ferrous materials**, such as brass, bronze, aluminum, or copper-beryllium alloys, are classified as "spark resistant" or "non-sparking." While no tool is completely incapable of sparking, these softer alloys have a significantly lower probability of generating an intense, incendiary spark when impacted or rubbed against other materials, making them mandatory for use in hazardous (classified) locations where explosive atmospheres are present. ### Why the other options are incorrect: **A) fixed with a ferrous cover:** This option is contradictory to safety requirements. A "ferrous cover" implies the cover is made of iron-containing steel, which is the exact type of material that must be avoided because it can produce incendiary sparks. **C) high carbon steel:** High carbon steel is the standard material for most heavy-duty hand tools (like wrenches, hammers, and screwdrivers) because it is hard and durable. However, its hardness and iron content make it highly prone to creating sparks upon impact, thus making it dangerous and prohibited for use in explosive gas environments. **D) approved by the Coast Guard:** While the Coast Guard may regulate certain equipment on vessels or maritime facilities, tool standards for explosive atmospheres are primarily dictated by occupational safety and health organizations (like OSHA in the U.S.) and specialized standards (like NFPA or ATEX/IECEx). Furthermore, an agency's approval does not define the *material* property (spark resistance) that is required for safety in this specific situation. The material composition (non-ferrous) is the critical safety factor.