Units Three and Five Energy Transmission Using Fluids Both Liquids and Gases qualify as fluids since each takes the shape of its container and will produce flow. However, gases compress and liquids are relatively incompressible.

Liquids and Gases A molecule consists of two or more atoms in chemical combination. Liquid Molecules Gaseous Molecules

Molecular Energy Molecular energy is the movement of molecules within a substance Molecular energy is affected by temperature.

Fluids take the shape of their containers

Gases and Heat Energy

Gas Temperature, Pressure, Compression, and Inefficiency Boyles Law of Gas Compression

Hydraulic Transmission of Energy

Pneumatic Transmission of Energy

Hydraulic Accumulator

Positive Displacement Pump

Positive Displacement Compressor

Pump Types 1. Gear

2. Piston Pump Types

3. Vane Pump Types

Resistance and Pressure Any influence that restricts the movement of fluid is resistance and will effect pressure. The systematic relationship between resistance and pressure is directly proportional.

Heat generation in Fluids When energy is consumed to overcome resistance, energy changes form. The energy is transformed into heat energy. Examples: Heat from lighting Heat from machine bearings. Heat from friction

Viscosity Viscosity is the measure of a liquids resistance to flow. As a “liquid” takes on heat, its viscosity will change.

Measuring Viscosity Viscosity is measured in units called Saybolt Universal Seconds or SSU. This is the time it takes for a liquid to flow through an orifice of a exact size when the fluid is at a certain temperature.

Viscosity and Friction generate Heat A liquid resists movement, this is resistance. A sharp bend or turn is resistance. Fluid moving too fast through through a conductor generates heat because of resistance. The rate of movement of fluid per foot is referred to as velocity.

Viscosity and Friction generate Heat (continued) Maximum velocities for fluids Oil: 10 to 30 feet per second depending on pressure. 15 fps is a general rule. Womack, Vol1, page 37. Gas: 1100 fps, “critical velocity.” For oil velocity: GPM x.3208/Area

Pressure Differential When ever a fluid is moving through a conductor and there exists a difference between pressure between any two points, the difference is called a pressure differential or “delta-P.”

General System Design Avoid sharp turns, obstructions, and anything that would disturb flow. Also consider pipe size.