LearnChemE

#### Manometry: Screencast

An overview on manometers and how they are used to determine force differentials.

We suggest you list the important points in this screencast as a way to increase retention.

##### Important Equations:

For a piezometer tube, the pressure in the pipe or container $$P_{A}$$ is: $P_{A} = \gamma_{1} h_{1} + P_{atm}$ where $$\gamma_{1}$$ is the specific weight of the fluid in container A, $$h_{1}$$ is the height of fluid A in the manometer, $$\gamma_{2}$$ is the specific weight of the manometer fluid, and $$h_{2}$$ is the height of the manometer fluid.

The pressure difference in a differential U-tube manometer can be derived by expanding on the U-tube manometer design equation: $\gamma_{1} h_{1} + P_{A} = \gamma_{2} h_{2} + \gamma_{3} h_{3} + P_{B}$ where $$P_{B}$$ is the pressure in container B, $$\gamma_{3}$$ is the specific weight of the fluid in container B, and $$h_{3}$$ is the height of the fluid in container B. All the other variables are the same as in a U-tube manometer.

The equation for an inclined manometer can be derived by expanding the equation for a differential U-tube manometer. $P_{A} – P_{B} = \gamma_{2} l_{2} sin( \theta ) + \gamma_{3} h_{3} – \gamma_{1} h_{1}$  where $$l_{2}$$ is the length of the manometer tube and $$\theta$$ is the angle of the tube.