What is the difference between the Hall Tube and the Collins Tube?
The Hall Tube is a self-averaging pitot tube with impact holes (openings in the tube facing the oncoming flow) all across the inside diameter of the pipe. The reading sent to the manometer is an averaged flowrate. The Hall Tube is inserted through a single drilled and tapped hole in the pipe. The Collins-Style Tube is a single point pitot tube, which is positioned at key points across the inside diameter of the pipe to obtain an averaged result. The readings are usually taken at 2, 6 or 10 separate points along the inside diameter. Each of these readings is averaged with the others by the user to obtain an averaged flowrate. The Collins-Style Tube is inserted through the pipe via two drilled and tapped holes in the pipe, 180 apart in the side of the pipe.
