What would happen if valve "25" shown in the illustration, vibrated open with the unit in operation? Illustration MO-0111

Correct Answer: Option A — The absolute pressure of the unit would increase, causing a decrease in distillate output.

Valve 25 typically controls the vacuum breaker or air vent. If it vibrates open, atmospheric air enters the vacuum system, increasing absolute pressure. This rise in pressure raises the boiling point of the feed water, reducing the evaporation rate and significantly decreasing the total distillate output of the unit.