At what psi should the fuel system pressure relief be set if the maximum deadhead pressure is 125 psi?

The correct answer involves determining an appropriate safety margin above the maximum deadhead pressure for the fuel system pressure relief setting. The maximum deadhead pressure, which is the maximum pressure that the system can withstand without damaging components, is stated to be 125 psi.

Setting the relief pressure too close to the maximum deadhead pressure can be risky, as it doesn’t provide sufficient allowance for pressure fluctuations that can occur during operation. A common practice is to set the relief valve pressure at approximately 10% higher than the deadhead pressure.

Calculating this, 10% of 125 psi is 12.5 psi. Adding this value to the maximum deadhead pressure results in a relief setting of 125 psi + 12.5 psi, equaling 137.5 psi. This approach ensures that the relief valve activates before pressures reach a dangerous level, effectively protecting the fuel system from potential damage.

Thus, the correct answer of 137.5 psi aligns with the typical procedure of ensuring adequate pressure relief settings to maintain system integrity and safety.