🔍 Key Concepts

• Difference in how relief valves and safety valves open in response to overpressure (gradual vs. pop-action) • Meaning of setpoint pressure and how the valve behaves just above that point • Definition of blowdown (the pressure drop needed for a valve to reclose) in typical relief vs. safety valve design

💭 Think About

• Think about which device is usually used on boilers for sudden steam overpressure and how you would want that valve to open: slowly or very quickly? • For each option, ask yourself: is this a fundamental, widely-taught design difference, or is it something that could vary by manufacturer? • Focus on how the disc actually moves as pressure just exceeds the setpoint: does it creep open or does it snap fully open?

✅ Before You Answer

• Be sure you can clearly state to yourself: relief valve = ?-type opening, safety valve = ?-type opening. • Verify that you understand blowdown as the pressure range from opening to reseating, and which type of valve is normally associated with a small, sharp blowdown. • Double-check that spring orientation (compression vs tension) and gagging capability are not reliable universal distinctions for exam-style questions.