The hi-hi alarm should be calibrated to a fill level of what percent?

The hi-hi alarm should be calibrated to a fill level of what percent?

• A. 95
• B. 92
• C. 98
• D. 100

Answer: (C)

The main idea is that the hi-hi alarm is a final warning before a tank is completely full, giving time to stop filling and prevent overflow. Calibrating it to about 98 percent leaves a small ullage margin for liquid expansion, slosh, and instrument accuracy, so you can react before reaching full capacity. Setting the level at 100 percent would offer no headroom and increases the risk of an overflow if the liquid expands or the gauge readings drift. A lower setting like 95 or 92 percent would trigger too early, reducing operational efficiency without providing additional safety benefits. Therefore, 98 percent is the best choice to balance safety and practical operation.

The main idea is that the hi-hi alarm is a final warning before a tank is completely full, giving time to stop filling and prevent overflow. Calibrating it to about 98 percent leaves a small ullage margin for liquid expansion, slosh, and instrument accuracy, so you can react before reaching full capacity. Setting the level at 100 percent would offer no headroom and increases the risk of an overflow if the liquid expands or the gauge readings drift. A lower setting like 95 or 92 percent would trigger too early, reducing operational efficiency without providing additional safety benefits. Therefore, 98 percent is the best choice to balance safety and practical operation.