🔍 Key Concepts

• Atmospheric pressure in psia (pounds per square inch absolute) and how it relates to 14.7 psia at sea level • Typical pressure-vacuum relief valve settings on tank vessel cargo tanks are only slightly above and below atmospheric pressure, not very high • Difference between tank design pressure and PV valve operating pressure

💭 Think About

• Start by asking: what is standard atmospheric pressure in psia, and which choice is closest to that value on the pressure side? • Look at how many psi above and below atmospheric each choice represents. Which one looks like a realistic small overpressure and small vacuum for a cargo tank? • Think about safety: PV valves are meant to protect the tank from slight over- and under-pressure, not to operate at large pressure differences. Which option reflects that idea?

✅ Before You Answer

• Identify which option has a pressure value closest to 14.7 psia, representing normal atmospheric pressure • Calculate the difference (in psi) between the high and low values in each answer choice and compare how large those swings are • Verify that the chosen range looks like a modest deviation from atmosphere, not a very high pressure range more suitable for pressure vessels, not typical cargo tanks