Abstract: Water flow through air/water spray heads of an automatic in duct humidification and evaporative cooling system for buildings is modulated by a pneumatic control signal delivered to rear chambers of the system's spray heads through a pneumatic signal reversing relay connected with a pneumatic signal sending line in the pneumatic control section of the system.

Abstract: An in duct humidification and evaporative cooling system for industrial and commerical buildings is disclosed. Air and water under pressure are utilized to atomize water into minute droplets which rapidly evaporate and raise the level of relative humidity while producing evaporative cooling. A first relative humidity sensor/transmitter produces a signal proportional to the relative humidity of return air, and a second relative humidity sensor/transmitter provides a signal proportional to the relative humidity of supply air. Preset receiver-controllers external to the duct receive the two signals and send them to a low signal selector which in turn sends the lower signal to a modulating water valve and to an electrical switch which opens a valve in the pressurized air supply line. A second electrical switch operatively connected in the air supply line opens a valve in the pressurized water supply line.

Abstract: To reduce substantially the amount of tubing for condensate being returned from the steam distribution manifold and to enable such condensate to revaporize as steam, thereby increasing the thermal efficiency of the humidifier, a condensate baffle in the bottom of the steam distribution manifold projects with the manifold into the steam separator through a common coupling between the separator and manifold and downstream from the steam admission needle valve of the separator. Structural compactness with economy is achieved.