Abstract: A bi-directional, clean or grey medium, wide temperature range, low intrusion, low turbulence, mass flow meter extends multiple pressure sensing tubes, each containing multiple pressure sensing ports, into a bounded path a distance no more than one half the diameter of the path, or semi-traversing. These sensing tubes sense impact or static pressures to obtain a sensing pressure, and are in fluid communication with a channel located externally of the bounded path which provides a total average sensing pressure for measurement. A series of reference pressure ports are located flush to the wall surface of the bounded path to obtain a reference pressure. These reference ports are in fluid communication with another channel located externally of the bounded path which provides a total average reference pressure for measurement. The difference in total average sensing pressure and total average reference pressure can be measured and used to calculate the average velocity and volume of gas within the bounded path.