If valve "D" is opened during the normal operation of the distiller shown in the illustration, which of the events listed will occur? Illustration MO-0111

Correct Answer: Option D — The amount of vapor being formed in the evaporator will decrease.

Opening valve D typically bypasses jacket water flow or alters the feed/vacuum balance in the evaporator. This reduces the heat input available from the jacket water, lowering the evaporation rate and decreasing total distillate production.