Real Dictionary

static tube in American English
a tube with openings in its walls, inserted in a fluid in motion so that the flow is across the openings and used to measure the static pressure of the fluid
noun: a tube for measuring the static pressure of a fluid in motion, so placed in the fluid as not to be affected by the pressure changes caused by the motion of the fluid

static tube in British English
noun: an open-ended tube used to measure the static pressure at a point in a moving fluid and positioned in such a way that it is unaffected by the fluid's motion