Question

A water filled vertical u-tube manometer is used to measure pressure changes in a reaction vessel. Assuming that the change in height of the manometer can be measured to a precision of 1/16" of an inch, how accurately can pressure changes (in psi) be measured?

Answer 1

Answer:

The pressure will be measured to a precision of 0.073 psi.

Explanation:

Since the relation between the measurement of pressure and height is given by

$dP=\rho gh$

For water we have

$\rho _{water}=62.4lb/ft^3$

$g=32.17ft/s^2$

Applying the given values we get

$dP=62.4\times 32.17\times \frac{1}{16\times 12}=5.433lb/ft^2\\\\=\frac{10.455}{144}lb/in^2=0.073psi$