How Does a Fluid System Work?

Mechanism of a Fluid System

• In 1650, Blaise Pascal, a French scientist, discovered the principles of the fluid system. The primary force that drives a fluid system is pressure. Changes in the pressure of the fluid cause it to move, which drives the system. The fluid must be enclosed and pressure applied to force the fluid to move in the desired direction. The two types of fluid systems hydraulics and pneumatics. Within each of these types, there are open and closed systems.

Hydraulics

• A hydraulic system harnesses the power of a pressurized liquid. Some liquids that can be used are oil, gasoline or water. Each hydraulic system must have a reservoir for the liquid, a pump, valves to control the pressure and flow of the fluid and a motor or hydraulic cylinder to move the required load. Hydraulic systems are considered the stronger of the two types of fluid systems.

Pneumatics

• A pneumatic system gathers power from a pressurized gas or air. When compressed air expands, the result is kinetic energy. When a valve in the tank is opened, the pressure inside the tank will expand to match the atmospheric pressure outside the tank. The air pressure must be controlled at each point in the system for the pneumatic system to work properly. Hydraulic systems tend to use much higher pressures than do pneumatic systems. Pneumatic systems are considered to be faster than hydraulic systems. In a pneumatic system, the amount of force is equal to the pressure times the area. The pressure in a pneumatic system is given in pounds per square inch. The area may be in square inches or meters. The force is then reported in pounds.

Closed Fluid Systems

• A closed fluid system is one that retains and reuses the fluid involved in the function of the system. Some examples of closed systems include: the human body, a hydraulic motor, a garden water feature and a car's brake fluid system.

Open Fluid Systems

• An open fluid system is one in which the fluid passes through the system only once. Examples of open systems include a garden hose, a fuel pump and a municipal water system.