1. FLUID FLOW FOR CHEMICAL ENGINEERING Dr Mohd Azmier Ahmad Tel: +60 (4) 5996459 Email: chazmier@eng.usm.my EKC 212 CHAPTER 8 (PART 2) TRANSPORTATION SYSTEM & FLUID METERING

2. Valves Oil and gas, power generation, mining, water reticulation, sewerage & chemical manufacturing would constitute the majority of valves used by industry. Valve regulates the flow of a fluid by opening, closing, or partially obstructing various passageways. It can work on :   fully open or fully closed,   reduce pressure or flowrate of a fluid,   one directional flow,   water & gas to pass while holding back the steam   control temperature/pressure/liquid level. A sailor aboard a ship operates the wheel controlling a fuel valve.

3. Basic Valve Construction

4. Valve Characteristics

5. a) Gate valve  Diameter of opening where a fluid passes is nearly the same as the pipe.  Takes many turns to completely open or close a gate valve.  Direction of flow is the same.  Large opening of valve leads to small pressure drop.  Constructed from cast iron, cast carbon steel, gun metal, stainless steel & alloy steels.

6. Gate valve

7. b) Globe valve  Outside is globe shaped.  Typically globe valves are made of metallic alloys. Normally used for controlling flow.  Opening increases almost linearly with stem position.  Change in direction whenever the fluid passes the disc.  Contributes to high pressure drop.  Gives better flow control than gate valve.

8. Globe valve

9. c) Ball valve  Opens by turning a handle attached to a ball inside the valve.  The ball has a hole through the middle so that when the port is in line with both ends of the valve, flow will occur.  Sealing element is spherical in shape.  Reduce the problems of alignment.  Body of ball valves is made from metal, plastic or metal with a ceramic center.  The ball is often chrome plated to make it more durable  Normally used to control flow.  Mainly for on-off operations.

10. d) Check Valves  Only permits one directional flow.  Valve only opens when there is pressure form in the direction of the flow.  Automatically stops when the flow stops

11. Check valve Lift / piston check valves Swing check valves

12.  Mechanical device for moving or controlling a system.  An actuator takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion. e) Actuator