THE FACILITY WAS CHOSEN FOR INSPECTION DUE TO A RELEASE OF AMMONIA ON JULY 5, 2006. THERE A 2 SENSORS IN THE COMPRESSOR ROOM THAT ARE SET AT 50 PPM (WARNING) AND 150 PPM (ALARM). SENSORS ARE INTERLOCKED WITH FANS AND THE KING VALVE SOLENOID; LIGHTS ARE ACTIVATED AND CALL DOWN SEQUENCE ACTIVATED. FACILITY PERSONNEL STATED THAT SENSORS WERE TESTED AND CALIBRATED ANNUALLY. THE SENSORS WERE TESTED BY FACILITY AND EPA PERSONNEL; BOTH MANNING SENORS DID NOT WORK.