A pneumatic leak detector operates by submerging a nozzle in oil. Airflow from the nozzle results in simultaneous cavitation and atomization of the oil. Microscopic oil droplets form a fog, which is used to detect leaks in closed duct systems. The integrated valve and nozzle includes a stem on one end for air input, the nozzle on the other end for air output, and a check valve between the stem and the nozzle to prevent the backflow of air or oil. The exterior body of the integrated valve and nozzle is a convex body wedge. A smaller concave wedge is cut at the orifice of the nozzle. The critical parameters of the nozzle are its orifice diameter, body wedge angle, orifice cut angle, and orifice cut depth, all of which have been optimized by experimentation to yield maximal fog density.