PNEUMATIC CONTROL SYSTEM AND RESET VALVE FOR SUCH A SYSTEM OR THE LIKE

摘要

A pneumatic control system having a source of control fluid providing two different control pressure levels for respectively switching the control device of the system from one operating condition thereof to another operating condition thereof, the control device comprising a pair of condition controller means each having a sensor and a bleed type pneumatic valve operated thereby together with relay means operatively interconnected to the source for directing a branch signal of the control fluid to a pneumatically operated device in relation to a pilot signal directed to a pilot chamber of the relay means by one of the control means. A pressure responsive means is provided for switching the system from one condition controller means to the other in relation to the pressure level of the source, and a reset means is provided for overriding the pressure responsive means.