Experiment 2.docx

Experiment No. 2 MEASUREMENT OF PRESSURE HEAD USING MANOMETER 1. Objective(s): The activity aims to determine the pressure of liquid at various depths. 2. Intended Learning Outcomes (ILOs): At the end of the activity the students shall be able to: 

Define the basic principle of pressure.

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Demonstrate pressure head measurement using U – tube manometer.

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Describe pressure and elevation relationships of fluids.

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Identify pressure of liquid at a certain point.

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Use the principle of pressure to solve common problems with fluids columns.

3. Discussion: The intensity of pressure, at any point in a fluid, is the amount of pressure per unit area. P=F/A Pascal’s Law states: At any point in a fluid at rest, the pressure is the same in all directions. Variations in Pressures Consider any two points (1 & 2), whose difference in elevation is h, to lie in the ends of an elementary prism having a cross sectional area dA and a length of L. Since the prism is at rest, all forces acting upon it must be in equilibrium. P2 – P1 = wh Therefore, the difference in pressure between any two points in a homogeneous fluid at rest is equal to the product of the unit weight of the fluid (w) to the vertical distance (h). Also, P2 = P1+ wh

Meaning any change in pressure at point 1 would cause an equal change at point 2. Therefore, a pressure applied at any point in a liquid at rest is transmitted equally and undiminished to every other point in the liquid.

Consider that point 1 lies at the FLS (p1 = 0) then; P=wh A free liquid surface (FLS) is the surface which is subject to the atmospheric pressure (no gauge pressure) Consider that points 1 and 2 lies on the same elevation so that h = 0. Then; P1 = P2 Therefore, the pressure along the same horizontal plane in a homogeneous fluid at rest is equal. Note: w =unit weight of liquid h = height of fluid 4. Resources:  U – tube manometer  Mercury 

Rubber tubing

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Funnel

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Prophylactic or thin sheet of rubber

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Water

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Colored liquid

5. Procedure:  Cover the large end of the thistle tube/funnel with a piece of thin sheet of rubber. 

Attach a piece of rubber tubing over the smaller end of the funnel while the other end to the U – tube manometer that has two different liquid.

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Measure the height of the fluids in the U tube manometer.

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Tabulate the result.

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Repeat step 2 to 4 for other liquid.

Course: CE 402 Group No.: 3 Group Leader: Malvecino, Juztine M. Group Members: 1. Espino, Pamela Shara L. 2. Franco, Rebi Jennise J. 3. Macatangay, Jesuzette L. 4. Torcatos, Mark Lester C. 5. Victorio, Ace Louise B. 6. Data and Results: Trials (Fluid/s) Oil and Water Vinegar and Oil Diesel and Water Diesel and Vinegar 7. Observation:

h1 Oil = 12.2 Vinegar = 10.3 Diesel = 15.0 Diesel = 13.6

Experiment No.: 2 Section: CE41FB6 Date Performed: July 20, 2015 Date Submitted: August 03, 2015 Instructor: Engr. Richard G. Villamora

h2 Water = 8.4 Oil = 6.5 Water = 10.2 Vinegar = 9.4

Pressure 0.6924 0.5972 1.076 0.9347

We observed that the height of a given liquid in the manometer with rubber tubing that has a funnel covered with rubber is different when there is nothing attached to the manometer. Just like the previous experiment, the different liquids (Oil, Water, Vinegar and Diesel) don’t mix together. 8. Analysis/Computation: Oil and Water Oil and Vinegar Pow = (0.89)(9.81) Pov = (0.96)(9.81) (0.122) – (1)(9.81) (0.103) – (1)(9.81) (0.122-0.84) (0.103-0.65) = 0.6924

= 0.5972

Water and Diesel Pwd = (1)(9.81) (0.150) – (0.84)(9.81) (0.150-0.102) = 1.076

Diesel and Vinegar Pdv = (0.96)(9.81) (0.136) – (0.84)(9.81) (0.136-0.094) = 0.9347

9. Source of Error: One of the sources of error in this experiment is the estimation of height. We cannot tell the exact amount of fluid poured in the u – tube manometer because of the measuring tool used which is the ruler. 10. Conclusion:

We therefore conclude that the relationship between the elevation and pressure of fluids is; the higher the difference in elevation the higher the pressure will be on the closed surfaced.

Oil and Water Vinegar and Oil

Diesel and Water Diesel and Vinegar