Millwright Level 1 Practice Exam 2025 – All-in-One Guide to Master Your Certification!

Acetylene reaches its critical point at 29.4 PSI. When we consider the choices given, the closest and most accurate representation of acetylene's critical pressure is 28 PSI. At this pressure, acetylene transitions from its gaseous state to its liquid state, which is essential for safe handling and storage. Understanding the critical point is vital for millwrights who work with gases, as it determines the conditions under which acetylene can exist without converting to a liquid or reverting back to gas, allowing for proper equipment design and usage safety measures.