The valve will vent when the internal pressure reaches approximately _______ lbs psi?

• A. 5
• B. 10
• C. 15
• D. 20

Answer: (B)

A vent valve works by opening at a predetermined pressure to relieve excess pressure and protect the system. The set point is chosen so that the valve stays closed during normal operation, then opens as soon as pressure threatens to exceed safe levels, and it will tend to stay open until the pressure drops back under control. That set point needs to balance safety with efficiency: if it’s too low, you vent more than necessary and waste material and energy; if it’s too high, the system could over-pressurize before relief starts. In real life, the opening pressure is not exact—temperature, wear, and manufacturing tolerances cause it to occur approximately around the nominal value. Given these considerations, the most practical choice is the mid-range value among the options, which corresponds to a reasonable compromise between protection and venting frequency.