2.16 PITOT TUBE. The pitot (pronounced pee-toe) tube is a device that
senses both velocity and static pressure. It is inserted into a moving air
stream and connected to a manometer. The inside of the pitot tube is shown
in Figure 2-29. It is actually a tube within a tube. The inside tube
senses pressure at the end of the tube facing in the direction of airflow.
It senses the total pressure within the duct; that is, it senses velocity
plus static pressure. The hose connection to send this pressure to the
manometer is at the bottom of the pitot tube. A second hose is connected to
the fitting on the side of the pitot tube and reads pressure in the area
between the two tubes. This pressure is created by a series of small holes
around the circumference of the outer tube. As each of these holes is
perpendicular to the direction of airflow, they will sense static pressure
Pitot Tube Internals
The pitot tube may be used with a manometer to measure velocity pressure
or the static pressure in a duct by hooking it up as in Figure 2-30.
does not matter if the static pressure within the duct is positive or