Compressibility of Fluids Review and Equation
Fluid Flow Table of Contents
Hydraulic and Pneumatic Knowledge
Fluid Power Equipment
Compressibility of Fluids Review and Equation
Compressibility is the measure of the change in volume a substance undergoes when a pressure is exerted on the substance. Liquids are generally considered to be incompressible. For instance, a pressure of 16,400 psig will cause a given volume of water to decrease by only 5% from its volume at atmospheric pressure. Gases on the other hand, are very compressible. The volume of a gas can be readily changed by exerting an external pressure on the gas
Equation:
where V is volume and p is pressure
Earth Vertical, drained compressibilities
Vertical, drained compressibilities Material β (m²/N or Pa-1)
Material |
β (m2/N or Pa -1 ) |
Plastic clay |
2 × 10-6 – 2.6 × 10 -7 |
Stiff clay |
2.6 × 10 -7 – 1.3 × 10-7 |
Medium-hard clay |
1.3 × 10 -7 – 6.9 × 10 -8 |
Loose sand |
1 × 10 -7 – 5.2 × 10 -8 |
Dense sand |
2 × 10 -8 – 1.3 × 10 -8 |
Dense, sandy gravel |
1 × 10 -8 – 5.2 × 10 -9 |
Rock, fissured |
6.9 × 10 -10 – 3.3 × 10 –10 |
Rock, sound |
<3.3 × 10 –10 |
Water at 25 °C (undrained) |
4.6 × 10 –10 |
Ethyl alcohol |
110 × 10 –11 |
Carbon disulfide |
93 × 10 –11 |
Glycerine |
21 × 10 –11 |
Mercury |
3.7 × 10–11 |