The Collins-Style tube is a single point pitot tube that is inserted into the pipe through two 1/4″ FPT drilled and tapped holes.
Measurements are usually taken at two, six or ten points across the inside diameter of the pipe, and averaged to get the full flow of the water. Manometer readings are easily translated into gallons per minute using multipliers found in the users instructions.
COLLINS TUBE SIZE TABLE
The complete user instructions are available by clicking this link:
Collins Tube Instruction Complete.Optimized PDF File 1.3 MB