What is a Pump?\n\n\n\nAs per Merriam-Webster dictionary, \u201ca pump is a device\/machine that raises, transfers, delivers, or compresses fluids by suction or pressure or both\u201d. So a pump is a piece of mechanical rotary equipment that moves fluids\/slurries from the inlet through the outlet to transfer fluid to a desirable location. It increases the pressure (energy head) of the fluid and imparts velocity (energy) to help in the liquid movement. Refer to Fig. 1 which shows various types of Industrial Pumps used in Processing Plants.\n\n\n\nFig. 1: Various Types of Industrial Pumps\n\n\n\nWhere are pumps used? \n\n\n\nStarting from irrigation, water supply, gasoline supply, etc the pump finds its application in air conditioning systems, refrigeration, chemical movement, sewage movement, flood control, marine services, and finally in all industries like powerplants, process industries. Process Industries (Refinery, Oil & Gas, Chemical and Petrochemical Plants) can not be thought of without the application of pumps. That's why pumps are called the heart of a process plant.\n\n\n\nWhat are the types of pumps?\n\n\n\nRefer to the following charts that shows the major types of pumps used in industries:\n\n\n\nFig. 2: Types of Pumps\n\n\n\nFig. 3: Types of Overhung centrifugal pumps\n\n\n\nFig. 4: Types of Centrifugal Pumps between bearings\n\n\n\nFig. 5: Types of vertically suspended Centrifugal pumps\n\n\n\nFig. 6: Types of Positive displacement Pumps\n\n\n\nBrief Working Principle of Pumps\n\n\n\nKinetic Pumps\n\n\n\nIn Kinetic Pumps, a centrifugal force of the rotating element called an impeller, \u201cimpels\u201d kinetic energy to the fluid, moving the fluid from pump suction to the discharge. \n\n\n\nPositive Displacement Pumps \n\n\n\nPositive displacement pump uses the reciprocating action of a piston or squeezing action of meshing gears, lobes or other moving bodies to displace the media (entrained in the cavity) from one area to another (from suction to discharge).\n\n\n\nItems in a Pump Package\n\n\n\nRefer to the following image that explains the major items that constitute a complete pump package.\n\n\n\nFig. 7: Major items in a Pump package\n\n\n\nCodes and Standards for Pumps\n\n\n\nFew of the major codes and\nstandards that are used in process industries are listed below:\n\n\n\nAPI 610 \u2013 Centrifugal PumpsANSI B 73.1 \u2013 Horizontal Centrifugal PumpsANSI B 73.2 \u2013 Vertical inline Centrifugal PumpsAPI 674 \u2013 Positive Displacement-Reciprocating\npumpsAPI 675 \u2013 Positive Displacement-Controlled\nvolume PumpsAPI 676 \u2013 Positive Displacement-Rotary PumpsISO 2858 \u2013 End Suction Centrifugal PumpsISO 5199 \u2013 Centrifugal PumpsHI \u2013 Hydraulic Institute\n\n\n\nPump Selection criteria in Brief\n\n\n\nThe selection criteria of a pump is a very vast topic\/study based on the different experiences\/performances of various pumps in various fields\/services. \n\n\n\nBelow listed selection criteria are only a brief of the vast pump selection criteria. \n\n\n\nGenerally, a centrifugal pump is used for high flow, low to a moderate head and low viscosity. Whereas, a positive displacement pump is used for low flow (constant flow), high head and high viscosity. In the case of a centrifugal pump, the flow varies with the head. In the case of a positive displacement pump, the flow remains constant (at constant speed) even if the pressure is varied. Hence for metering services, positive displacement pumps are preferred. Flow can be varied by the use of either stroke adjustment or variable speed drive (VSD).\n\n\n\nCentrifugal Pump\n\n\n\nDepending on the flow, head and vendor\u2019s design range, the pump may be single-stage or multistage. For high head, either a multistage or a high speed integrally geared pump is used. \n\n\n\nFor sumps\/tanks, vertical centrifugal pumps are preferred. Also if the NPSHA is less (mostly in case of high vapor pressure services), a vertical barrel pump (VS6 \/ VS7) is preferred which uses a vertical can\/barrel as a casing for the impeller. This arrangement adds to the positive head on the suction side ultimately increasing the NPSHA\n\n\n\nPositive displacement pumps\n\n\n\nGear Pump\n\n\n\nThese are used for very high pressures and low flow\/metering service. The disadvantage with the gear pump is, if there is the presence of abrasive particles in the fluid, there may be erosion\/damage of gears during the meshing of the gears. Also, shear-sensitive fluids cannot be pumped with these pumps \n\n\n\nFig. 8: Different Types of Pumps\n\n\n\nVane Pumps \n\n\n\nSimilar in construction with internal gear pumps, these pumps have vanes that are free to move in a slot. These pumps can pump fluid containing vapor or gases. The limitation of these pumps is the discharge pressure. It can be used only up to moderate pressures. Fluid with solid suspension cannot be pumped with these pumps.\n\n\n\nDiaphragm pump\n\n\n\nThese are used for the metering applications giving accurate flow and toxic applications (where diaphragm rupture sensors are provided for detection of diaphragm rupture). In these pumps, the mechanical seal\/gland packing is not required for sealing the process fluid and hence preferred over piston\/plunger pumps in toxic applications. For very high viscosities, there is a limitation for the use of these pumps. Pulsations are also a limitation. \n\n\n\nFig. 9: Progressive Cavity Pump and AODD Pump\n\n\n\nPiston \/ Plunger Pumps\n\n\n\nSimilar to other positive displacement pumps, this type is also used for high pressure, moderate\/low flows and high viscosity. The disadvantage of this pump is pulsations. However, a pulsation dampener may be used to reduce the pulsation problem. For lower flows, a plunger pump is used, for moderate flow, a piston pump is preferred.\n\n\n\nProgressive cavity pumps\n\n\n\nThese are preferred for very high viscosities, abrasives liquids, slurry service, shear sensitive liquids. Widely used in pulp, oil field, food products, paint and coating industries. The advantage is fewer pulsations, good efficiency due to close clearance. Limitations for these pumps is the speed. The rotor is eccentric, the increase in speed may lead to vibrations. High temperature is another limitation since the stator is lined with an elastomer material (Nitrile rubber etc). \n\n\n\nFig. 10: Vertical Sump Pump and Multi-stage Centrifugal Pump\n\n\n\nMultiple screw pumps\n\n\n\nThese are preferred for high viscosities, high pressures, moderate flow (higher flow as compared to gear pumps). One of the advantages of a screw pump is No pulsations in the flow as compared to the piston \/ plunger \/ diaphragm pumps.\n\n\n\nMagnetic drive pumps\n\n\n\nThese are used for toxic\/hazardous fluids where leakage of the fluid to the atmosphere is not permitted. These are seal-less pumps with canister, drive magnet and driven magnet. These are used for moderate pressures.\n\n\n\nFig. 11: Plunger Pump and Barrel Pump\n\n\n\nLobe pumps\n\n\n\nThese are widely used in food and drug industries where frequent cleaning\/flushing of the pump internals is mandatory. Since then there is no metal to metal (timing gear is used for driving the driven lobe) there is minimal damage to the product. These pumps are suitable for CIP (clean in place). Due to complete drain-ability, the cross-contamination of the products is minimized\/prevented.\n\n\n\n Actual installation photographs \n\n\n\nFig. 12: Single Stage and 10-Stage Pump\n\n\n\nFig. 13: Vertical Inline Pump and Diaphragm Metering Pump\n\n\n\nFew more pump related resources for you..MAJOR FACTORS AFFECTING THE PUMP PERFORMANCE\u201d: A short articleNPSH for Pumps: Explanation and EffectWater Hammer Basics in Pumps for beginnersPumps & Pumping Systems: A basic presentationA brief presentation on \u201cCENTRIFUGAL PUMP WITH SPEED CONTROL\u201dStress Analysis of Pump Piping (Centrifugal) System using Caesar IIConsiderable points while Commissioning and starting-up a Process PumpConsiderable points while installing centrifugal pumps at site to reduce vibration\n\n\n\n\n\n\n\nDetailed Centrifugal Pump Course\n\n\n\nIf you are planning to become an expert in Centrifugal Pumps: Its Principles, Operation, Design then simply click here to join the video course. And believe me, through the course you will get an answer to all your queries.