🔍 Key Concepts

• psia vs psig (absolute pressure vs gauge pressure) • Standard atmospheric pressure ≈ 14.7 psi at sea level • Relationship: psig = psia − atmospheric pressure

💭 Think About

• Is the given turbine exhaust pressure measured relative to a perfect vacuum or relative to atmospheric pressure? • What is the gauge pressure when the absolute pressure equals atmospheric pressure? • If a gauge is open to the atmosphere, what would it read when the system is exactly at atmospheric pressure?

✅ Before You Answer

• Confirm that psia (pounds per square inch absolute) includes atmospheric pressure. • Confirm that psig (pounds per square inch gauge) is pressure above atmospheric pressure only. • Check what the gauge would read when the fluid pressure is exactly equal to standard atmospheric pressure (14.7 psia).