What are 2 differences between a pneumatic system and a hydraulic system?

*There are two types of fluid power systems: Pneumatic Systems - These systems have two main features: a) Pneumatic systems use compressed gas such as air or nitrogen to perform work processes. b) Pneumatic systems are open systems, exhausting the compressed air to atmosphere after use. Hydraulic Systems - These systems also have two main features: a) Hydraulic systems use liquids such as oil and water to perform work processes. b) Hydraulic systems are closed systems, recirculating the oil or water after use. One of the main differences between the two systems is that in pneumatics, air is compressible. In hydraulics, liquids are not. What are the advantages of pneumatics? In pneumatics, a system needs only one power source. The work process creates a lower noise level than hydraulic systems, and pneumatic systems are relatively clean and operate at high speed. And of course of major concern to the customer, pneumatic systems feature lower component costs.  more