Minnesota Boiler License Practice Exam

What is the maximum allowable pressure above which a spring in a safety valve for pressure up to 250 lbs psi should not operate?

1. 2% above or 2%

2. 6% above or 6%

3. 10% above or 10%

4. 12% above or 12%

The correct answer is: 10% above or 10%

The correct answer is that the maximum allowable pressure for a safety valve set for pressures up to 250 psi should not operate above 10% of the set pressure. This is aligned with safety standards that dictate safety devices must function within specific operational limits to ensure the protection of equipment and personnel. A safety valve is crucial for preventing excessive pressure build-up in systems, as it opens to relieve pressure and prevent potential hazards such as explosions or system failures. For a safety valve set at or below 250 psi, operating above 10% of the set pressure would exceed safe operational limits, risking failure to respond appropriately to excess pressure situations. This standardization ensures that all safety devices maintain their integrity and functionality under expected operating conditions. Hence, by maintaining a maximum allowable pressure at 10% over the set point, equipment can operate within safe parameters while providing robust protection against overpressure scenarios. Understanding the rationale behind these limits is vital for anyone working with boilers and safety systems.