Tiene la forma mostrada en la siguiente figura. La forma de esta curva es la representada en la siguiente figura. Os muestro una imagen que explica como obtenerla. Esto es todo de momento. Por favor, dejadme vuestros comentarios e inquietudes. Muy buena la informacion mi hermano es precisa y muy didactica, definitavamentw el mundo de las turbomaquinas es apasionante.
Gracias por tu comentario. Un saludo. Esta muy bien explicada su exposicion. Lo Felicito!!!!. Sin embargo le falto hacer un solo grafico de las 4 curvas que caracterizan el funcionamiento de las bombas centrifugas. Geracias por la informacion en estos momenos estoy preparando un curso sobre bombas centrifugas y el articulo me sera muy util.
Saludos desde Venezuela! Hola Pedro, simplemente coloca los puntos donde indica. Gracias por comentar. Gracias por la ayuda…. La velocidad la tome directamente del tablero de la diesel pero se mantuvo en RPM. Lo felicito por entregar sus conocimientos y compartirlos con todos. Muy bien explicado, gracias! Ahora me puedes ayudar en cual es la diferencia en el funcionamiento entre una bomba centrifuga y una bomba sumergible, muchas gracias!
KSB Aktiengesellschaft has been manufacturing centrifugal pumps for more than years. Our product range has been extended continuously. We offer the right pump for every application and special requirement — and that at top results.
The product range is perfectly complemented by KSB's reliable services. Our more than 2, employees support your systems throughout their entire life cycle. Original KSB spare parts and our global hour service prevent costly downtimes. On request, service specialists certified by the KSB Group conduct comprehensive system analyses at your site in order to increase the profitability and performance of your pump systems.
To find out more, and to contact us, please visit our Service Pages.
KSB introduced its first centrifugal pump to the market in Since then, the industry itself and, with that, the demands placed on fluid handling equipment have changed tremendously. We have always been aware of the pump playing an important part in the economic success of a system.
O que é uma curva NPSH e qual é a sua importância?
This is why the KSB Group has always designed its technology with your success in mind. For example by launching the first stainless steel centrifugal pump, Etachrom, inwe enabled the hygienic handling of both liquid foods and corrosive fluids. The company makes sure that each and every one of its pumps and other products generates maximum results in energy efficiency and operating reliability. Many products already satisfy the EU regulations for ; some of them even those for In these times of rising energy prices, saving energy clearly does reduce operating costs.
To continuously improve in operating reliability, KSB engineers have never ceased to optimise their current pump portfolio. In earlythe company launched its latest centrifugal pump on the market: MegaCPK.
It is characterised by low NPSH values, high operating reliability, smooth running and stable operating behaviour. With its casing and interiors being made of stainless steel, this pump is particularly well-suited to pumping aggressive chemical fluids.
In the Pumps and Automation brochure you will find pumps for almost any flow rate and power rating.Log In. BigInch -born in the trenches. Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The Eng-Tips staff will check this out and take appropriate action. Click Here to join Eng-Tips and talk with other members! Already a Member? Join your peers on the Internet's largest technical engineering professional community.
NPSH (Altura de Aspiración Positiva Neta)
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¿Sabes Qué es la Curva Característica de Una Bomba Centrífuga?
Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. I am comfertable calculating NPSHa for centrifugal pumps but I am confused about calculating it for vertical turbine pumps.
Correct me if Im wrong, but NPSH is basically calculating how close the liquid is to boiling due to low pressure in the intake. With vertical turbine pumps the impellers are submerged so you would never experience low pressures in the intake. Why then is NPSH even calculated for vertical turbine systems?
It seems like the major question is if the pump is powerful enough to push the liquid up the piping to the level at where it is discharged and be able to overcome any friction losses in the piping. The NPSHa calculation gives you the resulting head of liquid that must be standing above the inlet of a pump in order to maintain that liquid above its flash point in the low pressure area of the inlet to the impeller. The requiremenet is usually given by the pump manufacturer based on empirical data or actual testing.
This is true whether or not the pump is horizontal or vertical. Do an advanced search on this forum for NPSH. There have been many many threads devoted to the topic. Don't feel intimidated by being new. If you do the search you can see that plenty of folks with lots more experience struggle with NPSH also. Ask more questins if you don't find the answers after the search. Thanks for the quick response. I did search on here for about 15 minutes and didn't find the answer to my question.
If anyone could point me to a thread that discusses this I would appreciate it. RMW said it all. NPSH is the same for any pump, vertcle, horizontal, split flow.Con ello podemos resolver ciertos problemas sobre la bomba ocasionados por tener un punto de trabajo fuera del rango previsto.
Este concepto es de la mayor importancia y debe recordarse siempre. Para ello tenemos varias alternativas. Como estos dos factores se multiplican para llegar a la potencia absorbida, vemos que esta potencia se incrementa ocho veces.
Por favor, dejadme cualquier comentario o duda que al respecto os surja. Que pasa si por calculo la Altura Manometrica de mi sistema da 7m. Hola Alfredo.
Veo que tu sistema lo tienes definido. Cuando dices que el sistema tiene una altura de 7 m. Un saludo. Espero haberte aclarado algo. Gracias por tu comentario. Hola Mario, sinceramente desconozco el software que se utiliza en este tipo de test.
Hola, Tengo un caso real; haciendo el calculo de perdidas la curva del sistema pasa por debajo de la curva de la bomba sin cortarla. Puede que tenga un consumo enorme y la potencia de la misma no sea suficiente para proporcionar todo el caudal demandado por el sistema. Mario, mira este link para adquirir un software donde puedes ingresar curvas de las bombas y cruzarlas con el sistema. A veces nos liamos con temas que pueden simplificarse mucho.
Con una simple lectura visual de varios puntos obtenemos lo que buscamos. Gracias, un saludo. Muchas gracias. Lo importante es comprender bien el significado de las curvas, ellas te dan todas las respuestas. Te explico como yo lo entiendo y a ver si es correcto.
Esta medida seria la perdida de carga del sistema. Ese es el caudal que esta pasando por el sistema, no? No dudes en preguntar si no lo ves claro. Hola Eliel, lo mejor es sacar varios puntos de la curva de la bomba trabajando en tu sistema. Espero que te aclare algo. Hola, no te disculpes, este medio es para resolver dudas y tratar de ayudar. Hola Pablo, en efecto, puedes variar el caudal hasta el extremo de dejarlo a cero.Boiling starts when the pressure in the liquid is reduced to the vapor pressure of the fluid at the actual temperature.
In practice we can measure the head at the pump suction flange. Be aware that - depending of the design of the pump - the contribution to the NPSH value from the suction flange to the impeller can be substantial. The vapor pressure in a fluid depends on the temperature. Waterour most common fluid, starts boiling at 20 o C if the absolute pressure is 2. For an absolute pressure of At an absolute pressure of The NPSH a can be estimated during the design and the construction of the system, or determined experimentally by testing the actual physical system.
For a common application - where the pump lifts a fluid from an open tank at one level to an other, the energy or head at the surface of the tank is the same as the energy or head before the pump impeller and can be expressed as:.
If the pump is positioned above the tank, the elevation - h e - is positive and the NPSH a decreases when the elevation of the pump increases lifting the pump. At some level the NPSH a will be reduced to zero and the fluid will start to evaporate. If the pump is positioned below the tank, the elevation - h e - is negative and the NPSH a increases when the elevation of the pump decreases lowering the pump.
It's always possible to increase the NPSH a by lowering the pump as long as the major and minor head loss due to a longer pipe don't increase it more.Usando o Excel - Como construir Curvas de Bomba
It is important - and common - to lower a pump when pumping a fluid close to evaporation temperature. The NPSH rcalled as the Net Suction Head as required by the pump in order to prevent cavitation for safe and reliable operation of the pump. The required NPSH r for a particular pump is in general determined experimentally by the pump manufacturer and a part of the documentation of the pump.
The available NPSH a should in general be significant higher than the required NPSH r to avoid that head loss in the suction pipe and in the pump casing, local velocity accelerations and pressure decreases, start boiling the fluid on the impellers surface. Pumps with double-suction impellers has lower NPSH r than pumps with single-suction impellers.
A pump with a double-suction impeller is considered hydraulically balanced but is susceptible to an uneven flow on both sides with improper pipe-work. When elevating a pump located above a tank lifting the pump - the fluid starts to evaporate at the suction side of the pump at what is the maximum elevation for the actual temperature of the pumping fluid. At the maximum elevation NPSH a is zero. The maximum elevation can therefore be expressed by modifying 4f to:.
For an optimal theoretical condition we neglect major and minor head loss. The elevation head can then be expressed as:.
The maximum elevation - or suction head - for an open tank depends on the atmospheric pressure - which in general can be regarded as constant, and the vapor pressure of the fluid - which in general vary with temperature, especially for water. The absolute vapor pressure of water at temperature 20 o C is 2. The maximum theoretical elevation of a pump when pumping water at 20 o C is therefore:. Due to head loss in the suction pipe and the local conditions inside the pump - the theoretical maximum elevation normally is significantly decreased.
Maximum theoretical elevation of a pump above an open tank at different water temperatures are indicated below. Suction head for water - or max. To limit cavitation in a hot water system. Note that the NPSH specifications provided by manufacturers in general are for use with cold water. For hydrocarbons these values must be lowered to account for vapor release properties of complex organic liquids. The head developed by a pump is independent of liquid and a performance curve for water can be used for Newtonian liquids like gasoline, diesel or similar.
Note that the required power to the pump depends on the liquid density and must be recalculated. NPSH calculations might be modified if there is significant amount of dissolved gas in a liquid.
The gas saturation pressure is often much higher than a liquid's vapor pressure.O motor apresenta uma energia motriz Hm que deve ser transferida ao rotor. Isto faz com que Hreal seja menor do que Ht Figura 3. A Fig. Tipo de Curva H-Q Ascendente. Isto caracteriza uma bomba com curva de carga ascendente.
Bombas com curvas opostas a esta se denominam curvas de carga descendentes. Diferentes tipos de rotores podem ser utilizados num determinado corpo. Na Fig. Por exemplo, para um ponto i.
A partir destes dados tabele e grafique o resultado de 02 bombas iguais conectadas em serie e de 02 bombas iguais conectadas em paralelo. O mesmo pode ser realizado para os demais pontos da tabela.
Exemplo 3. Rotor com entrada radial. Determinar e graficar a curva de potencia da bomba. Determinar a Eq. Graficar o resultado de duas bombas iguais conectadas em serie. Graficar o resultado de duas bombas iguais conectadas em paralelo.
A Tabela-1 mostra os dados resultados da potencia sendo graficados na figura abaixo. Altura Manometrica m 30 Muito mais do que documentos Descubra tudo o que o Scribd tem a oferecer, incluindo livros e audiolivros de grandes editoras. Iniciar teste gratuito Cancele quando quiser. Enviado por Nozes Da Castanha. Data de envio Feb 27, Jump to content. Low Flow in Pipes - posted in Ankur's blog.
Posted 07 February - AM. The cure you show is normal. But I don't think you know how to read it. Look for some basic information on centrifugal pump curve and how to read it. Are you a student?
Yes siractually i am confused with efficiency curve in curve with RPM efficiency is upward parabola and in curve with RPM efficiency is downward parabola - why efficiency has been shown in two ways? Posted 07 February - PM. That's how the pump behaves.
You don't need to understand the behavior. You only need to know how to read the curves. Posted 08 February - PM. I believe the efficiency curve is actually a series of ellipses, but we only plot the part that is in the zone, so it looks like a parabola.
Sometimes you are in the bottom half and sometimes in the top. Posted 16 February - PM. The normal operation should be preferably done close this best efficiency point for minimum power requirements.
Community Forum Software by IP. Featured Articles Check out the latest featured articles. File Library Check out the latest downloads available in the File Library. New Article Product Viscosity vs. Featured File Vertical Tank Selection. You cannot start a new topic Please log in to reply. I have also attached the performance curve. Posted 07 February - AM The cure you show is normal. Posted 07 February - AM Yes siractually i am confused with efficiency curve in curve with RPM efficiency is upward parabola and in curve with RPM efficiency is downward parabola - why efficiency has been shown in two ways?
Posted 07 February - PM That's how the pump behaves. Posted 08 February - PM I believe the efficiency curve is actually a series of ellipses, but we only plot the part that is in the zone, so it looks like a parabola. Kindly tell whether I am wrong or right?? Sign In Need an account? Register now! I've forgotten my password. Remember me This is not recommended for shared computers.
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