1. MECH1300 Basic Principles of Pneumatics Topics Absolute Pressure and Temperature Gas Laws Gas Flow Vacuum Pneumatic Systems Chapter 10

2. MECH1300 Basic Principles of Pneumatics Comparison HYDRAULICSPNEUMATICS Uses a relatively incompressible liquidUses a compressible gas Slow, smooth motionQuick, jumpy motion Very preciseNot as precise as hydraulics Self LubricatingLubricant must be added Not as cleanCleanest Pressures of 500 to 5000 psiPressures around 100 psi

3. MECH1300 Absolute Pressure and Temperature

4. MECH1300 Absolute Pressure and Temperature

5. MECH1300 Gas Laws

6. MECH1300 Gas Laws

7. MECH1300 Gas Laws

8. MECH1300 Gas Laws Gay-Lussac’s Law – The absolute pressure of a confined gas is proportional to its temperature, provided its volume remains constant. Used when heating or cooling gases.

9. MECH1300 Gas Laws

10. MECH1300 Gas Laws

11. MECH1300 Gas Laws Charles law – The volume of a confined gas is proportional to its temperature, provided its pressure remains constant.

12. MECH1300 Gas Laws

13. MECH1300 Gas Laws General Gas Law – relates temperature, pressure and volume. (nothing remains constant)

14. MECH1300 Gas Laws

15. MECH1300 Gas Laws Adiabatic Process – none of the heat is transferred to the atmosphere, so the temperature of the gas will increase to a maximum when compressed or expanded. The temperature changes without heat being added. k is a constant that measures the heat absorption properties of the gas, for Air k =1.4

16. MECH1300 Gas Laws

17. MECH1300 Gas Flow

18. MECH1300 Vacuum Use pressures that are below atmospheric pressure to create suction. Used for pick and place to lift and manipulate parts. Measured in inches of mercury (Hg), using a mercury barometer. mmHg in metric

19. MECH1300 Vacuum Mercury is used because it is a heavy liquid. At sea level the air pressure will push mercury to a height of 30 inches. 30 in Hg represents a perfect vacuum. At higher elevations, it will be less than 30 in Hg because atmospheric pressure is lower. A vacuum generates less force at higher elevations.

20. MECH1300 Vacuum

21. MECH1300 Vacuum EX: A suction cup with an inside diameter of 3 in is used in a vacuum system that pulls 20 in Hg. What is the maximum lifting force? The negative indicates that the object is being drawn toward the suction cup

22. MECH1300 Vacuum EX: A suction cup with an inside diameter of 40mm is used in a vacuum system that pulls 200mmHg. What is the maximum lifting force?

23. MECH1300 Pneumatic Systems 3 segments – 1.Power Supply – Power supply segment (compressor, receiver tank). Prime mover is still usually an electric motor. Compressor pumps air into the receiver tank, storing air. System draws air from the tank as needed. 2.Control Valves – directional, pressure and flow 1.Output – actuator (motor, cylinder) and load