# U tube manometer

by Physicist3
Tags: manometer, tube
 P: 54 I have been told to calculate the pressure drop between two points in a pipe carrying water using a U-tube manometer. I understand that the pressure drop (P1 - P2) is given by pgh and that h is the difference in manometer fluid levels and g is gravity, but is p the density of the manometer fluid or the water flowing through the pipe?
 P: 82 Exactly, p1-p2 = gh(density(manometer fluid) - density(water))
P: 54
 Quote by pukb Exactly, p1-p2 = gh(density(manometer fluid) - density(water))
In the case im referring to, the manometer fluid has a lower density than the water. For a pipe, is the pressure drop measured using a utube manometer simply ρmanometergh?

P: 82

## U tube manometer

it is not a good idea to use a fluid of lower density in manometer than the density of fluid in the pipe. a higher density fluid is used to make measuring instruments smaller. for example, mercury will require a space 13.6 times smaller than water for same pressure rise or drop.

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