Manometer Lab

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Manometer Lab

Manometer - a device to measure gas pressure

There is one type of manometer we will deal with and it is called a U - tube manometer. It is a glass tube filled with a liquid (usually water or mercury) with one side of the U or water column opened to the air (therefore at atmospheric pressure, Patm) and the other side exposed to the pressure of a gas (Pgas). The difference in the level of the liquid in each tube shows the relative (and if doing the math, actual) difference in pressure between the gas and the atmosphere.

The simplest U - tube manometer is a flexible straw (flexed so bottom looks like U ) filled with a little water. The gas pressure is from you blowing in air or sucking on straw.


1. Each group, get a flexible straw and plastic cup.

2. Fill cup with water.

3. Put flexible end of straw into water and then suck up the water.

4. While still sucking up the water, place finger on the end of straw that is under water. Then flex the straw to make the U tube. You must do this under the water level for it to work.

5. Make observation of the liquid level on each side of the tube once they equalize out.

6. While one partner sucks up on the straw/liquid, the other observes the water level change. Make observations

7. Repeat except for gently blowing into straw.Make observations


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Last edited April 23, 2007 10:41 am (diff)