Abstract: The present disclosure describes an air sampling system which is particularly effective in detecting minute quantities of smoke caused by electrical short circuits in equipment housed in an air cooled cabinet. More, specifically, the system is useful where large number of rack-mounted printed circuit cards are employed. The system employs air sampling cylinders mounted in proximity to the cards, and through the establishment of a pressure differential, causes an air sample to be drawn into the tubes and through a detector box which includes a smoke detection unit. The presence of smoke is conveyed to a control box which responds by removing electrical power to the cards, thereby averting further damage to the cards or surrounding structures.