The word that “Cats” stands for is corrosive. Corrosives are substances that can burn or wear away skin, eyes, metals, and other materials on contact. The image of a cat eating away at things is a handy cue for this kind of damage, which is why it’s used to remind you that the term represents corrosive hazards. Toxic or poison describe systemic harm from exposure rather than local tissue or material destruction, and explosive refers to a rapid release of energy—neither fits the cue as well as corrosive does.

Non-pressure fixed facilities are designed to operate at essentially atmospheric pressure, with only tiny fluctuations. That means the pressure is around 0 psig, i.e., just above or equal to ambient, typically staying within a narrow window like 0 to 0.5 psig. The other ranges involve substantial pressure above ambient (tens of psi or more), which would classify the equipment as pressurized rather than non-pressure. So the 0 to 0.5 psig range best fits the description.

Capacity refers to the space inside a cargo tank that can actually hold bulk material, expressed in cubic feet. For dry bulk cargo tanks, a common per-tank size used in practice is about 1500 cubic feet, which is roughly 42.5 cubic meters. This per-tank capacity is what you use to estimate how much cargo weight can be loaded (weight depends on cargo density), and to figure total capacity when there are multiple tanks. The value 1500 cubic feet reflects that standard size, making it the best choice.

Vapor pressure is the pressure exerted by the vapor that forms above a liquid when the two phases are in balance at a specific temperature. In a closed system, molecules continuously evaporate from the liquid surface and some return as they condense; at a given temperature, the rate of evaporation equals the rate of condensation, and the vapor above the liquid settles at a characteristic pressure—the vapor pressure. This pressure rises with temperature because more molecules have enough energy to escape into the vapor phase. Boiling occurs when this vapor pressure matches the surrounding atmospheric pressure. The other descriptions don’t capture this specific concept: atmospheric pressure is the external pressure on the system, not the vapor pressure of the liquid; the pressure of gas in a closed container could include many gases and isn’t necessarily the vapor pressure; and the partial pressure of a non-condensable gas refers to its share of the total pressure, not the pressure of the liquid’s vapor in equilibrium.