Centrifugal Pump

A centrifugal pump is a pump that is rotodynamic in nature that employs the use of a turning impeller to increase a liquids pressure. These are commonly used to move liquids through piping systems. The liquid enters in the pump following a path near its axis which is rotating. After entry, its speed is quickened by the impeller, which leads to the fluid flowing in the outward direction. After entry into the diffuser, it makes an exit into the piping system downstream, and that's why these pumps prove to be a great help due to the fact that they make larger discharges via smaller head.

The inspiration for the centrifugal pump is believed to have originated from a water lifting machine that was invented by the Italian engineer Francesco di Giorgio Martini, in 1475, that according to a Brazilian historian is thought to be the prototype of a pump that applies centrifugal force. The first true centrifugal pump was invented in 1600, by Denis Papin. However, Papin's pump had straight vanes instead of curved ones, and centrifugal pumps began to have curved vanes no earlier than 1851, introduced by the British inventor John Appold.

A centrifugal pump functions by converting the moving force of kinetic energy, which is often a result of a rotating electric motor or turbine, to an heightened static liquid pressure. Bernoullui's principle describes this action. As the pump impeller rotates, it imparts kinetic energy to the fluid as it is being drawn in from the impeller eye and is forced outward to the periphery. The fluids kinetic energy changes as it exits the impeller and is converted to static pressure due to the change in area the fluid experiences in the volute section. This static pressure occurs because the area the fluid experiences in the volute section is changed. One of the main factors for this is the volute shape of the pump casing or the vanes that are responsible for this conversion. The main purpose of the diffuse is to slow down the liquid and convert the kinetic energy into flow work and as a result, the pressure on the downstream side of the pump increases, causing flow.

Centrifugal pumps have their fair share of problems of course, including Erosion, Corrosion, Overheating Due to Low Flow, Leakage, and Surge, and thus they need to me regularly maintained. The Energy Usage of a centrifugal pump can be estimated quite easily, depending on the flow required, the height lifted, and the total length of the pipeline.

George Edmondson is an accomplished writer about Centrifugal Pumps. For more information on Centrifugal Pumps visit http://www.centrifugalpumpguide.com

Pump Information and Detail

Pumping of liquids is almost universal in chemical and petrochemical processes. The many different materials being processed require close attention to selection of materials of construction of the various pump parts, shaft sealing, and the hydraulics of the individual problems. A wide variety of pumps types have been developed to satisfy the many special conditions found in chemical plant systems; however, since all of these cannot be discussed here, the omission of some does not mean that they may not be suitable for a service. In general, the final pump selection and performance details are recommended by the manufacturers to meet the conditions specified by the process design engineer. It is important that the designer of the process system be completely familiar with the action of each pump offered for a service in order that such items as control instruments and valves may be properly evaluated in the full knowledge of the system.

A pump is a physical contrivance that is used to deliver fluids from one location to another through conduits. Over the years, numerous pump designs have evolved to meet differing requirements.

The basic requirements to define the application are suction and delivery pressures, pressure loss in transmission, and the flow rate. Special requirements may exist in food, pharmaceutical, nuclear, and other industries that impose material selection requirements of the pump. The primary means of transfer of energy to the fluid that causes flow are gravity, displacement, centrifugal force, electromagnetic force, transfer of momentum, mechanical impulse, and a combination of these energy-transfer mechanisms. Gravity and centrifugal force are the most common energy-transfer mechanisms in use.

Pump designs have largely been standardized. based on application experience, numerous standards have come into existence. As special projects and new application situations for pumps develop, these standards will be updated and revised. Common pump standards are:

1. American Petroleum Institute (API) Standard 610, Centrifugal Pumps for Refinery Service.
2. American Waterworks Association (AWWA) E101, Deep Well Vertical Turbine Pumps.
3. Underwriters Laboratories (UL) UL 51, UL343, UL1081, UL448, UL1247.
4. National Fire Protection Agency (NFPA) NFPA-20 Centrifugal Fire Pumps.
5. American Society of Mechanical Engineers (ASME).
6. American National Standards Institute.
7. Hydraulic Institute Standards (Application).

These standards specify design, construction, and testing details such as material selection, shop inspection and tests, drawings and other uses required, clearances, construction procedures, and so on.

The most common types of pumps used in a chemical plant are centrifugal and positive displacement. Occasionally regenerative turbine pumps, axial-flow pumps, and ejectors are used.
Modern practice is to use centrifugal rather than positive displacement pumps where possible because they are usually less costly, require less maintenance, and less space. Conventional centrifugal pumps operate at speeds between 1200 and 8000 rpm. Very high speed centrifugal pumps, which can operate up to 23,000 rpm and higher, are used for low-capacity, highhead applications. Most centrifugal pumps will operate with an approximately constant head over a wide range of capacity.

Positive displacement pumps are either reciprocating or rotary. Reciprocating pumps include piston, plunger, and diaphragm types. Rotary pumps are: single lobe, multiple lobe, rotary vane, progressing cavity, and gear types. Positive displacement pumps operate with approximately constant capacities over wide variations in head, hence they usually are installed for services which require high heads at moderate capacities. A special application of small reciprocating pumps in gas processing plants is for injection of fluids (e.g. methanol and corrosion inhibitors) into process streams, where their constant-capacity characteristics are desirable.

Axial-flow pumps are used for services requiring very high capacities at low heads.

Regenerative-turbine pumps are used for services requiring small capacities at high heads. Ejectors are used to avoid the capital cost of installing a pump, when a suitable motive fluid (frequently steam) is available, and are usually low-efficiency devices. These kinds of pumps are used infrequently in the gas processing industry.

To properly accomplish a good and thorough ratinghizing of a centrifugal pump, the plant system designer should at a minimum do the following.

1. Understand the fundamentals of performance of the pump itself.
2. Understand the mechanical details required for a pump to function properly in a system.
3. Calculate the friction and any other pressure losses for each "side" of the pump, suction, and discharge.
4. Determine the suction side and discharge side heads for the mechanical system connecting to the pump.
5. Determine the important available net positive suction head (NPSH,) for the pump suction side mechanical system, and compare this to the manufacturer's required net positive suction head (NPSH,) by the pump itself. This requires that the designer makes a tentative actual pump selection of one or more manufacturers in order to use actual numbers.
6. Make allowable corrections to the pump's required NPSH (using charts where applicable) and compare with the available NPSH. The available must always be several feet (mm) greater than the corrected required.
7. Make fluid viscosity corrections to the required performance if the fluid is more viscous than water.
8. Examine specific speed index, particularly if it can be anticipated that future changes in the system may be required.
9. If fluid being pumped is at elevated temperature (usually above 90o F (32.2o C )), check temperature rise in the pump and the minimum flow required through the pump.
10. Make pump brake horsepower corrections for fluids with a specific gravity different from water. Select actual driver (electric motor, usually) horsepower in order that horsepower losses between the driver and the pump shaft will still provide sufficient power to meet the pump's input shaft requirements.
11. If the pump has some unique specialty service or requirements, recognize these in the final sizing and selection. Consult a reliable manufacturer that produces pumps for the type of service and applications and have them verify the analysis of your system's application.

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My name is Bustanul Arifin. A chemical engineer who graduate from reputable university in the world. Now I am working as consultant in ethanol plant design, and petrochemical construction contractor. This article was written based on my experience and many text books. Please feel free to visit my website :

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Textbook reference :

1. Branan, C. R., "The Process Engineer's Pocket Handbook", Vol. 2, Gulf Publishing Co., 1983.
2. Brown, G.G., "Unit Operations", John Wiley and Sons, Inc. , 1950.
3. Evans, E L., "Equipment Design Handbook For- Rejneries and Chemical Plants", Vol. 1, 2nd Ed., Gulf Publishing Co., 1979.
4. GPSA Engineering Data Book, "Gas Processors Suppliers Association", Vol. 1, 10th Ed.. 1987.
5. Kern, R., "How to Design Piping for Pump-Conditions," Chemical Engineering, 1975.
6. Kirk, R.E. and Othmer, D.F., "Ensyclopedia of Chemical Technology", Interscience Ensyclopedia, Inc. , 1951.
7. Ludwig, E. E., "Applied Process Design for Chemical and Petrochemical Plants" Vol. 1, Gulf Publishing Co., 1977.
8. Perry, R. H., and Chilton, C. H., "Chemical Engineers' Handbook" New York: McGraw-Hill, Inc, 1973.
9. Standards for Steam Jet Ejectors, 3rd Ed., Heat Exchange Institute, New York, N.Y.
10. WALAS, Stanley M., "Chemical Process Equipment - Selection and Design",
(Butterworth-Heinemann Series in Chemical Engineering). Boston, MA: Butterworth-Heinemann, a division of Reed Publishing (USA) Inc., 1998.

12 Volt Pumps For Motorhomes, Caravans, Campers and Small Boats

Boats, caravans, and motorhomes use 12 volt pumps in several applications. Fresh water (Potable/drinking water) supply pressure and delivery is maintained by pumps. Sewage or effluent water may be removed with the help of a pump. But what type of pump should be used in a particular application?

All pumps work on the principle of creating a vacuum into which liquid is drawn. Liquid moves into the pump because of the air pressure on the surface of the large body of liquid into which the pump is placed or connected with by an intake pipe or hose. There are two basic ways in which that vacuum is created, and these differences are reflected in centrifugal pumps and diaphragm pumps.

Centrifugal pumps are very simple. A rotating impeller inside the pump forces water away from the centre of the passage, thus creating the vacuum. This design makes them cheap to manufacture, easy to maintain, and submersible. However, they are usually not self-priming, and can't handle many solids in the liquid matrix. They also cannot maintain an even pressure. There is a seal which prevents water from leaking into the motor. If these pumps run dry for very long the seal can be damaged.

Diaphragm pumps are larger and more complicated. They use a drive shaft to raise and lower a flexible diaphragm with each stroke. This changes the pressure inside the pump alternately opening and closing an intake and outflow valve, drawing water through. Diaphragm pumps require more maintenance, are not usually submersible because water should not contact the mechanical parts. They are initially more expensive. Diaphragm pumps are self-priming. Certain diaphragm pumps can handle dirty water and even debris because the liquid does not flow through the moving parts. They can also maintain a steady pressure, however without an accumulator tank water flow can pulse. Also, diaphragm pumps need to be mounted properly to prevent undue vibration.

Motorhome water pumps and caravan water pumps are usually centrifugal pumps. In addition to a submersible pump, an inline booster centrifugal pump can be added. Popular submersible brands of 12V pumps are the Whale GP881,Comet Elegant Immersion; Comet VIP Plus Immersion; and Comet GEO Plus Immersion. These range from a delivery rate of 8 litres/minute to 20 l/m. In size they vary from 38 to 43mm in diameter, making it an easy matter to slip them into the opening of water tanks. The Comet pumps have the ability to be run dry for up to 2 hours without damage, where as the Whale pumps strictly advise against being run dry.

Comet and Reich make inline booster centrifugal pumps. The delivery rate of these ranges from 11 to 18 l/m. These are slightly larger than the submersibles.

Diaphragm 12volt pumps for motorhomes and caravans are the Shurflo, Posiflo, and Fiamma. These pumps range in capability from 15 to 40 pounds per square inch pressure, at delivery rates of 7 to nearly 22 litres per minute. The largest of these is the Fiamma Aqua Pump capable of 10 litres per minute @21.75 psi (1.5bar). With a stainless steel filter and non-toxic parts these pumps are highly sanitary. They are resistant to deposits of scale and rust. Diaphragm pumps will not be damaged if it runs dry.

Marcle Leisure can supply various pump accessories such as additional filters, tubing, foot switches, non-return valves, expansion tanks (accumulators), and inline pressure switches.

Many 12 volt pump options are available from Marcle Leisure for caravan, motorhome, and small boat applications. By paying attention to the various types and brands of pumps and their capabilities the owner of a recreational vehicle can meet any need associated with the movement of liquids.

For a list of available
pumps and their accessories, visit http://marcleleisure.co.uk

Hayward's Super Pump Series - the Very Latest Technology

People who don't own pools have no idea of the time and resources that go into maintaining them. Not only is there the pool itself that has to be cleaned and maintained but there is all of the other unseen mechanical components that require input, with the pump being heart of your pools plumbing system.

New Convenience Features and Energy Efficiency

For years Hayward pool pump research engineers and designers have been hard at work coming up with new innovations for improving on pool pumps in general. The end result is the Hayward Super Pump series that is more energy efficient and contains features that make owning and maintaining a pool pump much easier.

See Through Hayward Pool Pump Screen Covers

For instance, Hayward Super Pumps all now feature a clear, see through screen sump cover. This means that unlike other standard pool pumps, the pump screen can be checked without having to remove the cover. Also new finger friendly flip levers make removing the cover a cinch.

Cooler Quieter Longer Lasting Hayward Pool Pumps

Hayward Super Pumps are also quieter and run cooler. It's all the direct result of new high tech cooling fans that operate far more efficiently. No more loud humming coming from the pool pump and a cooler pump is also a longer lasting pump.

Complete Lineup of Online Spare Parts

Spare parts for Hayward pool pumps are so easily available online. So now anything that you will need for your pump over the lifetime of your pool is simply a mouse click away on your computer. Look up your Hayward pool pump model, find the part you need on the parts schematics chart, click your mouse and it's in the mail the next day.

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Proper Sump Pump Maintenance is Vital to Keep Your Basement Dry

When do most homeowners find out that their sump pump has failed? When it is too late! It is raining cats and dogs, rain water is contributing to the ground water and the water table is rising quickly. As the ground water level reaches the float activation set point. Regularly the sump pump will kick on and keep the water level below the basement slab, thereby alleviating the hydrostatic pressure below the basement floor.

Sadly, many homeowners find out the hard way that their sump pump is not working properly. The water table rises beyond a controllable level and hydrostatic pressure begins forcing water through floor cracks and floor/wall joints. The outcome is increased moisture levels inside the basement, which can lead to poor indoor air quality conditions, and in severe cases can lead to standing water filling up inside the basement causing havoc and misery.

The most important thing homeowners with basement waterproofing systems (sump pumps, basement drainage, etc.) can do is complete regular factory recommended maintenance procedures included in the manual that came with the sump pump. If a basement waterproofing company or local contractor/plumber installed the system they should have given you the original product manual. Many waterproofing companies offer annual maintenance to assist you in the maintenance of your sump pump(s) and waterproofing systems. It is highly recommended that if you decide to go forward with contracted maintenance that you ask lots of questions about how the company will service the system.

Regular maintenance should include removal of debris and obstructions from the sump liner and any cleaning of filters or screens that are attached to the sump pump. It is recommended that drains and sump pump systems are flushed with hot water regularly. This ensures that any debris or iron bacteria colonies do not build up and become obstructions to the flow of water. Do not run any type of hazardous cleaning chemicals (bleach, ammonia, detergents, etc.) through any drain or sump pump systems.

If your sump pump has a removable screen (usually at the base) most waterproofing professionals should remove them and use a wire brush to clean the impeller of the pump. Proper maintenance should also include testing of the sump pumps operation and the float switch (if applicable). Water discharge lines should also be checked to ensure that the water being pumped out is flowing freely and to an area that will not allow the water to seep back into the basement.

If open drains are part of your basement waterproofing system (bulkhead trenches, garage trenches, etc.) be sure to test them for efficiency frequently. If your basement waterproofing system includes a battery back-up, it should also be tested and maintained. Any open-cell batteries should be filled to factory recommended levels with distilled water.

As mentioned earlier in this posting, always follow the factory recommended maintenance procedures. It is recommended that you have maintenance completed at least twice a year. The most important times to maintain your waterproofing systems are after prolonged dormant times and before typical heavy usage times. Every area is different but experience with Massachusetts weather patterns has proven that February (Winter thaw) and September bring the most sump pump failure complaints.

Lois Bartels is the owner of Green Bear Innovations, Massachusetts greenest home improvement company offering green insulation, basement waterproofing, foundation repair, sump pump installations, mold and radon assessment and remediation... We use energy efficient products, recycled/recyclable materials and hold a high standard for resource conservation during all installations. We are based in Reading, MA and serve the entire state and also RI, CT and NH.

Condensed Facts About Centrifugal Pumps

A centrifugal pump is defined as a rotodynamic pump that makes use of a rotating impeller to raise the rate of a fluid. If this is your first time to hear of this kind of equipment, you might perceive it as something that is quite complicated to use. But the truth is a centrifugal pump is considered one of the most uncomplicated forms of equipment. Its primary purpose is to switch the energy of an engine or an electric motor into kinetic energy or velocity, which will generate pressure to compel the fluid to come out.

Basically, the changes in the energy occur in two major parts of the pump-the volute and the impeller. The volute is the inactive part that turns the kinetic energy directly into pressure. Meanwhile, the impeller is the revolving part that turns the driver energy directly into the kinetic energy.

How It Uses Centrifugal Force

Centrifugal force is achieved when liquid goes into the pump suction as well as to the eye of the impeller. Once the impeller revolves, it instantaneously turns the liquid sitting in the hollows between imparts centrifugal acceleration and vanes outward. Now, as the liquid goes out from the eye of the impeller, a low pressure area is also created in the eye permitting more amount of liquid to come out into the pump inlet.

Multistage Centrifugal Pumps

A multistage centrifugal pump contains two or more impellers. These impellers can be installed on similar or different shafts. Basically, a multistage comprises two vital functions: to eject a large amount of liquid and to generate a high head.

If you want to produce a high head, the impellers should be installed on similar shaft, following a series pattern. Meanwhile, a large quantity of liquid can be released once the impellers are installed on different shafts, following a parallel pattern.

However, multistage centrifugal is only one among the three types of centrifugal stages of the pump. There is also the single stage pump; this stage is composed of only one impeller and is suggested for low head service. Another stage is the two-stage pump; this is made up of two impellers installed in series form for medium head service.

Three General Categories

Centrifugal pump is made up of three general categories: radial flow; mixed flow; and axial flow. Radial flow is a kind of pump wherein the pressure is increased completely by centrifugal force. Mixed flow, on the other hand, is a kind of centrifugal pump wherein the pressure is improved partially by centrifugal force and partially by the lift of the impeller's vanes on the fluid. Lastly, axial flow is a kind of centrifugal wherein the pressure is improved by the lifting action or propelling of the impeller's vanes on the liquid.

Impeller and Shafts: Vital Parts

Both the impeller and shafts are important parts of centrifugal pump. Primarily because certain speed is used to identify pump impellers depending on their proportions and types. Meanwhile, shaft is made up of shaft sleeves that go into the outer facade of the seal gland plate to guard the shafts from corrosion, wear, and erosion.

George Edmondson is an expert writer specializing on centrifugal pumps. Expand your knowledge on centrifugal pumps. Visit http://www.centrifugalpumpguide.com to obtain relevant information that is guaranteed to help you understand more about centrifugal pump without spending a single penny

Hydraulic Pumps

Hydraulic pumps convert mechanical energy and motion into hydraulic fluid power and are usually powered by gas or electricity. However, hand and air driven pumps are also utilized. There are three main types of hydraulic pumps used in the fluid power industry, namely vane pumps, gear pumps, and piston pumps. These are all positive displacement pumps, meaning that they transfer a calculated quantity of pressurized hydraulic fluid into a hydraulic system. This fluid progresses to the necessary component and its pressure is reconverted to mechanical force.

A general hydraulic pump design can be further categorized into specific groups. For example, piston pumps can be radial, axial, in-line reciprocating, or axial bent-axis piston pumps. Vane pumps are either cam or sliding vane pumps. Pumps can be further subcategorized according to the modifications made for special applications. These pumps show a great variety in design. Irrespective of the design, all hydraulic pumps are to be used with fluids of definite viscosity. Changes in fluid viscosity will cause altered performance, often lowering the efficiency. Most pumps get damaged by any solid particles in hydraulic fluid, and, hence, require a filtration system.

A hydraulic pump is a very important component of construction, manufacturing, and machining equipment. It is responsible for a machine's precision, its efficiency, and overall performance of an entire system. Various materials are used in hydraulic pumps to minimize wear and provide consistent performance. The type of material used varies according to pressures and temperatures that a hydraulic system will undergo. A number of plastics, synthetic rubbers, and steel alloys are used in the manufacturing of hydraulic pumps. High-strength alloys and polymers are used in high-pressure systems.

When choosing a pump, it is recommended to consider factors like operating pressure, temperature, and frequency. For applications requiring minimal pressures, less expensive, low-pressure pumps are available. Some examples of hydraulic pump manufacturers are Lifco Hydraulics, Inc., Flint Hydraulics, Inc., HYSECO, Inc., and Craft Fluid Systems.

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