1. Lesson 5
Fluid Systems

2. Fluid Systems
Water under pressure is used in many applications such as hydroforming
(the process of using water under high pressure to shape metal components)
and water jet cutting (the process of using water under high pressure and at a high cut speed to cut manufactured products

3. Volume flow rate The volume per second of a fluid flow; symbol qv.
The equation is , where qv is the volume flow rate, V is the volume, and ∆t is the time interval

4. Example 1
The volume flow rate needed to cut a material component is 3.3 L/min, and the time interval required is 18 s. Calculate the total volume of water used during this process.
qv= 3.3 L/min = L/s
∆t = 18 s
V =?

5. V = ∆t x qv
V = (18 s) x (0.055L/s)
V = 0.99L
Therefore the total volume of water needed is 0.99 L.

6. The speed of a fluid flowing through a pipe can also be an important piece of information.
Whether plumbing a house, or putting out a fire. The flow rate can be vital information.

7. The formula to find the speed can be derived from equation for flow rate: the total volume in a pipe of length l is Al, where A is the cross sectional area of the pipe.
Thus

8. Formulas

9. Example 2
Calculate the speed of water in a pipe of radius 0.21 mm if the volume flow rate of water is 6.0 x 10-6 m3/s
qv= 6.0 x 10-6 m3/s
r = 0.21 mm = 2.1 x 10-4 m
A = πr2
A = π(2.1 x 10-4 m)2
A = x 10-7 m2
v = ?

10. v = 43 m/s
Therefore, the speed of the water is 43 m/s

11. Fluid System Schematic Diagrams
The initial source of energy for the systems can be an electric motor or other device that drives a pump for liquids (liquids) or a compressor (gases). The pump or compressors transforms mechanical forces into fluid forces. The final output of the system is the actuator, a device that transforms fluid forces back into mechanical forces.
All of the components in a fluid system must form a circuit in which the fluid can flow.

12. Symbols are used to draw circuit diagrams of fluid systems
Symbols are used to draw circuit diagrams of fluid systems. The following symbols are commonly used in fluid system diagrams.

13. Transmission lines – the pipe through which the fluid travels
-continuous line - flow line
-dashed line - pilot, drain

14. Circular
-large circle - pump, motor
-small circle  - Measuring devices
-semi-circle - rotary actuator

15. Diamond 
- Fluid conditioner (filter, separator, lubricator, heat exchanger)

16. one square  - pressure control function 
two or three adjacent squares  - directional control

17. Triangle
-solid - Direction of Hydraulic Fluid Flow
-open - Direction of Pneumatic flow

18. Shut-Off Valve

19. Single acting cylinder
-returned by external force
-returned by spring or extended by spring force

20. Miscellaneous Symbols
Spring
Flow Restriction

21. Double acting cylinders
-single piston rod (fluid required to extend and retract)
-double ended piston rod

22. Directional control valve (3 ports / 2 positions)
-Normally closed directional control valve with 3 ports and 2 finite positions
-Normally open directional control valve with 3 ports and 2 finite positions.

23. Manual Control
-general symbol (without showing the control type)
-pushbutton
-lever
-foot pedal

24. Mechanical Control
-plunger or tracer
-spring
-roller
-roller(one direction only)

25. Questions
During hydroforming, a force of magnitude 1.8 x 106 N is applied to a piece of steel 12 cm x 14 cm. Calculate the pressure, in pascals and kilopascals on the piece of steel. T(1) C (1)
In a water jet cutting process, a stream of water with the speed 1.6 x 102 m/s drills a hole of radius mm with a force of magnitude 1.2 x 102 N. The process lasts for 16 s. Calculate.
The pressure, in pascals of the water on the metal . T (1)
The volume flow rate of the water T (1)
The total volume of water used in the process, in cubic meters. T (1)

26. What are the main uses of valves in a fluid system? C (1)
Name and draw the circuit for the type of device that controls : C (2)
A hand-held sprinkler
The hand pump used to inflate a tire.
Would you recommend a hydraulically operated or a pneumatically operated robot that needs to respond quickly and efficiently to all types of loads and must operate at many temperatures. T (1) C (1)