Dry-steam electrically operated humidifiers operate by means of a solenoid valve, which is energized by a humidistat. When the relative humidity drops slightly below the desired level set by the humidistat (see Fig. 3-16), a solenoid valve actuated by the humidistat admits steam from the separating chamber to the reevaporating chamber. Steam passes from this chamber through the muffler directly to the atmosphere. The fan (which is energized when the solenoid valve opens) assists in dispersing the steam into the area to be humidified. When the relative humidity reaches the desired level, the humidistat closes the solenoid valve and stops the fan.
