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

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

Valve 25 usually serves as an atmospheric or vacuum breaker vent. If it vibrates open, air enters the vacuum space, increasing the absolute pressure within the evaporator. This rise in pressure elevates the boiling point of the seawater, significantly reducing the evaporation rate and the resulting distillate output.