Abstract: A temperature responsive pneumatic control device comprising a receptacle containing a temperature responsive fluid therein, the receptacle being in open communication with a first diaphragm which in turn is in movable communication in a piston capable of being displaced by movement of the diaphragm, the piston being in communication with a rod attached to a second diaphragm and extending on both sides thereof such that the end of the rod downstream from the diaphragm is in communication with an air supply valve, which upon displacement gives a pneumatic signal to a pneumatic device such as a ridge vent in a building.

Abstract: An active ridge vent designed for providing varying degrees of ventilation at the ridge of a building such as a livestock building. An arm in combination with a triangular member, a linkage, and a channel allow the opening created by two opposed doors which are hinged to the open peak of a gable roof to vary. The opening is designed to vary in accordance with the temperature level in the livestock building.