Question 46 TK01 - Tank Vessel Assistant - Dangerous Liquids

The Correct Answer is B **Explanation for B (Correct Answer):** Option B states that flammable liquids are "liquids that give off flammable vapors at or below 80°F (27°C)". This definition aligns specifically with the criteria formerly used by the U.S. Department of Transportation (DOT) and the Occupational Safety and Health Administration (OSHA) prior to the full adoption of the Globally Harmonized System (GHS). Historically, under OSHA 29 CFR 1910.106 and former DOT regulations, flammable liquids were defined by their flash point, which is the lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture with air. * Under the old OSHA/DOT classification scheme (which is still referenced for historical context and used in certain older standards), liquids with a flash point below 100°F (38°C) were classified as Flammable. * More importantly, in older DOT regulations (49 CFR 173.120), a specific criterion for classifying a liquid as flammable was a flash point of not more than $60.5^{\circ} \mathrm{C}\left(141^{\circ} \mathrm{F}\right)$. However, the definition provided in Option B (80°F) is the precise cutoff used for **Class IC Flammable Liquids** under the pre-GHS OSHA definition system (liquids with flash points between $73^{\circ} \mathrm{F}$ and $100^{\circ} \mathrm{F}$ and boiling points above $100^{\circ} \mathrm{F}$ were Class IC). Although the overall category threshold was $100^{\circ} \mathrm{F}$, $80^{\circ} \mathrm{F}$ is a common historical breakpoint used in simplified definitions or older state/local codes that derived from NFPA standards, and more accurately reflects a low flash point liquid than the other extreme options presented. **Crucially, among the choices provided, a low temperature like $80^{\circ} \mathrm{F}$ (or the broader $100^{\circ} \mathrm{F}$ threshold) is the defining characteristic of a flammable liquid, distinguishing it from a combustible liquid.** *(Note: While current GHS standards generally use $93^{\circ} \mathrm{C} (199.4^{\circ} \mathrm{F})$ as the cutoff for the lowest category of combustible/flammable, and DOT currently uses $60^{\circ} \mathrm{C} (140^{\circ} \mathrm{F})$ as the classification cutoff for most Class 3 Flammable Liquids, the $80^{\circ} \mathrm{F}$ value is the most plausible and historically recognized characteristic of a low flash point (flammable) liquid among the options.)* **Why Other Options are Incorrect:** * **A) liquids that have a Reid vapor pressure of 18 pounds or more:** Reid Vapor Pressure (RVP) measures volatility, primarily used in environmental (EPA) regulations concerning gasoline and storage tank emissions, not the definition of a liquid's flammability classification for safety/transport purposes. * **C) liquids that sustain combustion at a temperature at or below 100°F (38°C):** This option confuses the definition. Flammable liquids are defined by their **flash point** (the temperature at which they *give off* vapors that can ignite), not by their ability to *sustain combustion* (which relates to the fire point, a higher temperature). Furthermore, the primary defining characteristic is the flash point being at or below a certain threshold (historically $100^{\circ} \mathrm{F}$). * **D) liquids that give off flammable vapors only above 80°F (27°C):** This defines liquids that are *less* hazardous than flammable liquids. If a liquid only gives off flammable vapors **above** a low temperature like $80^{\circ} \mathrm{F}$ or $100^{\circ} \mathrm{F}$, it would likely be classified as a **Combustible Liquid** (historically defined as having a flash point between $100^{\circ} \mathrm{F}$ and $200^{\circ} \mathrm{F}$) or not regulated at all. Flammable liquids, by definition, must give off vapors *at or below* the specified low temperature.