Valves and pump

Here the some overview of some important and essential valves and pumps in the engineering work.

1. VALVES & PUMP

2. Group members ASH1603024 ASH1603027 ASH1603031 ASH1603045 ASH1603053 ASH1603062

3. Valves are used to control the rate of flow of liquids in a pipeline. Valves are placed between pipes. During maintenance of pipes. Valves can be removed and repaired without disturbing the other connected units. Valves are designed in such a manner that they should withstand the following effects: Pressure of flow Temperature changes Strain from connected pipes. Distortion from the sealing surfaces INTRODUCTION

4. CLASSIFICATION A number of valves have been designed. Some of them are : (1) Plug cock valve (2) Globe valve (3) Gate valve (4) Diaphragm valve (6)Quick opening valve (5) Check valve etc.

5. PLUG COCK VALVE Essentially plug cock consists of a body casting in which a conical plug is fitted. The plug has an opening (cylindrical bore) through which the liquid passes . Some packing materials are included around the stem to close it. The sides of the plug should not be parallel or tapered too much . These valves are used when either complete opening or complete c losing is desirable Special design valves include lubricants at the stem of the cock . CONSTRUCTION

6. Advantages & Disadvantages Advantages : ( 1 ) Plug cock valves are used for handling compressed air. (2) These are used for the purpose of wide opening or complete closing conditions . Disadvantages : Though it is simple, it has several disadvantages . (1) Plug cock valves are not suitable for steam or water because of the cock material (2) It is difficult to turn the valves when the plug gets easily wedged in the body f irmly . This problem is observed when the sides of the plug are too nearly parallel (3) Sometimes the plug comes out of its seat, if the plug sides are tapered too much (4) It is difficult to regulate the flow. In normal designs, the area of opening changes rapidly even with slight rotation of the stem. Similarly, now does not change appreciably when the valve is opened fully

7. GLOBE VALVES Globe Valves A globe valve consists of a globular body with a horizontal internal partition. The passage of fluid is through a circular opening, which can be opened or closed by inserting a disc in the opening. The disc is positioned on the ring. which is known as seat ring. The disc can be rotated freely on the stem. Globe valve is installed in the high-pressure side connecting he narrow portion o f the disc. Globe valves can be connected in horizontal lines as well as in vertical lines.

8. Advantages & disadvantages Advantages Globe valves are mainly used in pipes with sizes not larger than 50 millimetres . In horizontal lines, these valves prevent complete Drainage. Disadvantages : Rust. scales or sludge prevent the opening of the valve.

9. GATE VALVES Gate Valves A wedge-shaped, inclined-seat type of gate is most commonly used. The pressure on the gates is controlling factor in large valves. Two types of gate valves are available. In non-rising stem valve, the thread of the valve stem engages the gate. The gate can be raised and lowered without the movement of stem through the stuffing box. The advantage is that the overall length of the stem required is less. In the rising stem valve, the length of the stem is more, since the stem and gate are a single piece . Advantages : (1). Gate valves are available in large sizes. (2) These are available in a variety of designs to suit the conditions. (3) Gate valves minimize the differential pressure during opening and stopping the flow.

10. DIAPHRAGM VALVES Diaphragm Valves Diaphragm is a flexible physical barrier. These valves are made of fabric reinforced, natural rubber and/or synthetic rubber faced with Teflon , a flurocarbon resin. Use Diaphragm valves are more suitable for fluids-containing suspended solilds , Special types of diaphragms can be easily sterilized so that they can be used in the production of sterile products.

11. ADVANTAGES & DISADVANTAGES Advantages (1) Diaphragm valves can be installed in any position. ( 2) Pressure drop is negligible . (3) Complete draining in horizontal lines is possible. (4) Simple. (5) Replacement of diaphragm is easy, there is no need to remove the valve from the line. Disadvantages : (1) Diaphragm valves are applicable to pressures of approximately 340 kilopascals (2) Maintenance cost increases because of replacement of faulty diaphragms. (3) These valves are expensive.

12. QUICK OPENING VALVE Quick Opening Valves In the gate valve stem is threaded therefore a number of turns is necessary to close the valve completely. Water hammer When a liquid is flowing in a pipe, it is associated with considerable kinetic energy due to its mass and velocity. When şuch a flow is suddenly stopped, the velocity is suddenly destroyed. since liquids are incompressible . t he energy appears as an intense shock . Sometimes , this shock c an be about 60 times the velocity of the fluid Hence, Q2 valves are vessel only in short line. On large lines , the valve should be closed slowly

13. Check valve Check Valves These valves are used when unidirectional flow is desirable. Protective mechanism is included to prevent: t he reversal of flow . These are automatically opened. When the low of liquid builds up the pressure. a ) swing check b ) b all check c) lift check vertical

14. PUMP

15. PUMP PUMP Pump is a mechanical device to increase the pressure energy of a liquid. In most of the cases, pump is used for raising fluids from a lower level to a higher level. A number of pumps have been developed to meet a variety of operating conditions. Their principles of working and construction are widely different.

16. CLASSIFICATION The classification of pumps are : Reciprocating pumps, examples are piston pump, plunger pump and diaphragm pump . Rotary pumps, examples are centrifugal pumps and gear pumps. Miscellaneous pumps, example is peristaltic pump.

17. Reciprocating pump Reciprocating pump is a positive displacement pump where certain volume of liquid is collected in enclosed volume and is discharged using pressure to the required application. Reciprocating pumps are more suitable for low volumes of flow at high pressures.

18. COMPONENTS Components of Reciprocating Pump 1 . Suction Pipe Suction pipe connects the source of liquid to the cylinder of the reciprocating pump. The liquid is suck by this pipe from the source to the cylinder . 2. Suction Valve Suction valve is non-return valve which means only one directional flow is possible in this type of valve. This is placed between suction pipe inlet and cylinder. During suction of liquid it is opened and during discharge it is closed. 3. Delivery Pipe Delivery pipe connects cylinder of pump to the outlet source. The liquid is delivered to desired outlet location through this pipe. 4. Delivery Valve Delivery valve also non-return valve placed between cylinder and delivery pipe outlet. It is in closed position during suction and in opened position during discharging of liquid . 5. Cylinder A hollow cylinder made of steel alloy or cast iron. Arrangement of piston and piston rod is inside this cylinder. Suction and release of liquid is takes place in this so, both suction and delivery pipes along with valves are connected to this cylinder.

19. COMPONENTS 6. Piston and Piston Rod Piston is a solid type cylinder part which moves backward and forward inside the hollow cylinder to perform suction and deliverance of liquid. Piston rod helps the piston to its linear motion. 7 . Crank and Connecting Rod Crank is a solid circular disc which is connected to power source like motor, engine etc. for its rotation. Connecting rod connects the crank to the piston as a result the rotational motion of crank gets converted into linear motion of the piston . 8. Strainer Strainer is provided at the end of suction pipe to prevent the entrance of solids from water source into the cylinder. 9. Air Vessel Air vessels are connected to both suction and delivery pipes to eliminate the frictional head and to give uniform discharge rate.

20. WORKING Working of Reciprocating Pump When the power source is connected to crank, the crank will start rotating and connecting rod also displaced along with crank. The piston connected to the connecting rod will move in linear direction. If crank moves outwards then the piston moves towards its right and create vacuum in the cylinder. This vacuum causes suction valve to open and liquid from the source is forcibly sucked by the suction pipe into the cylinder. When the crank moves inwards or towards the cylinder, the piston will move towards its left and compresses the liquid in the cylinder. Now, the pressure makes the delivery valve to open and liquid will discharge through delivery pipe. When piston reaches its extreme left position whole liquid present in the cylinder is delivered through delivery valve. Then again the crank rotate outwards and piston moves right to create suction and the whole process is repeated. Generally the above process can be observed in a single acting reciprocating pump where there is only one delivery stroke per one revolution of crank. But when it comes to double acting reciprocating pump, there will be two delivery strokes per one revolution of crank.

21. USES Oil drilling operations Pneumatic pressure systems Light oil pumping Feeding small boilers condensate return

22. Rotary pump   Rotary pump is the one by which the liquid can be transported based on the mechanism of rotation of one or more elements within a stationary casing . Generally rotary pumps are classified based on the nature of force applied in pumping. These are 1.Rotary positive displacement pump 2.Centrifugal pump

23. Rotary positive displacement pump Rotary positive displacement pump In the rotary positive displacement pump the liquid is mechanically displaced by the rotation of one or more elements within a stationary housing. One most common example of the rotary positive displacement pump is “GEAR PUMPS”

24. GEAR PUMP A gear pump is a type of positive displacement (PD) pump.  It moves a fluid by repeatedly enclosing a fixed volume using interlocking cogs or gears, transferring it mechanically using a cyclic pumping action.  It delivers a smooth pulse-free flow proportional to the rotational speed of its gears THE CONSTRUCTION OF A GEAR PUMP   TWO CIRCULAR GEAR: MESH WITH EACH OTHER.THESE RUN IN CLOSE CONTACT WITH THE CASING.THESE GEAR ARE ROTATE BY SOME EXTERNAL AGENCY.  How does a gear pump work? Gear pumps use the actions of rotating cogs or gears to transfer fluids.  The rotating element develops a liquid seal with the pump casing and creates suction at the pump inlet.  Fluid, drawn into the pump, is enclosed within the cavities of its rotating gears and transferred to the discharge.  There are two basic designs of gear pump:  external  and  internal 

25. USES Generally used in: Petrochemicals: Pure or filled bitumen, pitch, diesel oil, crude oil, lube oil etc. Chemicals: Sodium silicate, acids, plastics, mixed chemicals, isocyanates etc. Paint and ink. Resins and adhesives. Pulp and paper: acid, soap, lye, black liquor, kaolin, lime, latex, sludge etc. Food: Chocolate, cacao butter, fillers, sugar, vegetable fats and oils, molasses, animal food etc.

26. Centrifugal Pump Centrifugal Pump   centrifugal pump is a mechanical device designed to move a fluid by means of the transfer of rotational energy from one or more driven rotors, called impellers.  Fluid enters the rapidly rotating impeller along its axis and is cast out by centrifugal force along its circumference through the impeller’s vane tips.  The action of the impeller increases the fluid’s velocity and pressure and also directs it towards the pump outlet.  The pump casing is specially designed to constrict the fluid from the pump inlet, direct it into the impeller and then slow and control the fluid before discharge.

27. COMPONENTS Impeller.   Impeller is a rotor used to increase the kinetic energy of the flow . Casing (Volute).   The casing contains the liquid and acts as a pressure containment vessel that directs the flow of liquid  in  and  out  of the centrifugal pump. Shaft (Rotor).   The impeller is mounted on a shaft. Shaft  is a mechanical component for transmitting torque from the motor to the impeller. Shaft sealing.   Centrifugal pumps are provided with packing rings or mechanical seal which helps prevent the leakage of the pumped liquid. Bearings.   Bearings constrain relative motion of the shaft (rotor) and reduce friction between the rotating shaft and the stator. There are at least 5 common types of bearing Plain bearing Rolling-element bearing Jewel bearing Fluid bearing Magnetic bearing

28. USES Oil & Energy -  pumping crude oil, slurry, mud; used by refineries, power generation plants Industrial & Fire Protection Industry - Heating and ventilation, boiler feed applications, air conditioning, pressure boosting, fire protection sprinkler systems. Waste Management, Agriculture & Manufacturing - Wastewater processing plants, municipal industry, drainage, gas processing, irrigation, and flood protection Pharmaceutical, Chemical & Food Industries - paints, hydrocarbons, petrochemical, cellulose, sugar refining, food and beverage production Various industries (Manufacturing, Industrial, Chemicals, Pharmaceutical, Food Production, Aerospace etc.) - for the purposes of cryogenics and refrigerants.

29. Miscellaneous Pumps Miscellaneous Pumps A common miscellaneous pump is Peristaltic Pump Peristaltic Pump A   peristaltic pump  is a type of positive displacement  pump  used for pumping a variety of  fluids , they are also commonly known as roller pumps. The fluid is contained within a flexible tube fitted inside a circular pump casing

30. USES Peristaltic pumps are typically used to pump clean/sterile or aggressive fluids without exposing those fluids to contamination from exposed pump components. Some common applications include pumping IV fluids through an infusion device,  apheresis , aggressive chemicals, high solids slurries and other materials where isolation of the product from the environment, and the environment from the product, are critical. It is also used in  heart-lung machines  to circulate blood during a  bypass surgery , and in  hemodialysis  systems, as the pump does not cause significant  hemolysis . Peristaltic pumps are also used in a wide variety of industrial applications, especially agriculture as they are well suited for common agricultural chemicals. [7]  Their unique design makes roller pumps especially suited to pumping abrasives [8]  and viscous fluids. [9

31. Advantage/Disadvantages Advantages No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube, it is easy to  sterilize  and clean the inside surfaces of the pump. Low maintenance needs and easy to clean; their lack of valves, seals and  glands  makes them comparatively inexpensive to maintain. [7] They are able to handle slurries, viscous, shear-sensitive and aggressive fluids. Pump design prevents backflow and syphoning without valves. A fixed amount of fluid is pumped per rotation, so it can be used to roughly measure the amount of pumped fluid. Disadvantages The flexible tubing will tend to degrade with time and require periodic replacement. The flow is pulsed, particularly at low rotational speeds. Effectiveness is limited by liquid viscosity

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