The PMC-FP Innovations Air Content Probe and Control System has been designed specifically for use in the pulp and paper industry. It can also be used effectively in other applications where the measurement or control of air content is important, such as water/waste and mining industries. The System provides real-time measurement of entrained or injected gas content in a pre-determined zone of an aqueous suspension. Two PMC flush-mounted pressure sensors are placed in direct contact with process liquid. The sensors are typically fixed laterally on one or more pipes that are firmly held in place on a plate or in flanges mounted on the top or side of a tank, vessel or flotation cell.