| 摘要 |
A pneumatic switching apparatus is provided for a pneumatically controlled heating ventilating and air conditioning system of the type having an air supply line for supplying low pressure air to a pneumatic receiver-controller, a receiver controller which produces pneumatic output signals in dependence on pneumatic signals from pneumatic sensing devices and controlled valves which are actuated in dependence on the output signals. The apparatus includes an elongated manifold and a spool valve extending upward through the manifold. The manifold and spool valve are formed so that the receiver controller is connected to the air handling system when the spool valve is in an operating position. The manifold and spool valve are also formed so that the receiver controller is isolated from the air handling system and the air handling system is under manual control when the spool valve is in a calibration position. The manifold and spool valve may also be formed to connect the receiver controller to the pneumatic sensing devices when the spool valve is in the operating position, and to connect the receiver controller to a calibration port in the manifold and isolate the receiver controller from the sensing devices when the spool valve is in the calibration position.
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