UEB Bombas

8/13/2019 UEB Bombas

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BOMBAS PARA RIEGO

Ing. Agr. Marco A. Gonzlez


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Las bombas utilizan las fuerzas bsicas de la naturaleza paramover lquidos. Mientras la parte movil (impulsor, diafragma,pistn, etc) empieza a moverse, el aire es empujado fuera, elmovimiento del aire crea un vaco parcial que en este caso es

llenado con agua.

PRINCIPIO DE FUNCIONAMIENTO
http://www.hondapowerequipment.com/pumppics/atm.htm


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A nivel del mar, la naturaleza ejerce una presin de 14.7PSI alrededor de nosotros. Si pusiramos un tubo con un

extremo en el agua y ejerciramos un vaco al otroextremo la presin atmosfrica elevara una columna de

33.9 pies de alto

PRESIN ATMOSFRICA


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En la naturaleza, el movimiento es de mas denso a menosdenso, en los sistemas climticos las presiones altas semueven hacia las presiones bajas, en las bateras laspartculas positivas se mueven hacia las negativas.

Un lquido bajo alta presin se mover a un rea de menospresin si se le provee un conducto.

DIFERENCIAS DE PRESIN


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TIPOS DE BOMBAS

1. Equipo de bombeo

- Motor: A explosin o elctrico

- Bomba: De superficie o

sumergible

- Elementos de seguridad:Guarda motor, interruptores de

nivel y presin, electrodos


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Al trabajar la bomba centrfuga el impulsor gira, lo que fuerza elagua alrededor hacia la salida de descarga de la bomba. El vacoparcial creado, permite a la presin de aire de la Tierra forzar el

agua hacia el tubo de succin para reemplazar el agua desplazada.Cuando el agua entra al impulsor rotando, la energa del impulsor

es transferida al agua, forzando el agua hacia fueratangencialmente. Mientras el agua se desplaza mas agua entra a

ocupar el lugar vaco.

FUERZA CENTRFUGA


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SEALED SYSTEMIf a water pump is to create a partial vacuum in the pump housing,

three things must happen:

The pump must be primed. The water in the housing is essential tolubricate the mechanical seal so that it won't wear and leak.

The suction hose, hose seals and all O-rings must be in goodcondition so air can't be drawn in, losing the vacuum.

The impeller-to-volute clearance must be within specification toachieve the proper vacuum.
http://www.hondapowerequipment.com/pumppics/honpum.htmhttp://www.hondapowerequipment.com/pumppics/cenfor.htm


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HONDA PUMP TYPE DIFFERENCESThe size of the impeller and its vanes dictate whatpressures, discharge capacities and types of material thatcan pass through the pump. The impeller material,and thesize of the volute discharge opening, determine what sizematerial can pass through the pump without damaging it.

STANDARD (WP, WD)Deeper vanes will produce a larger discharge capacity.

MULTI-PURPOSE (WMP20X)Specially designed pump to to allow transfer of certain

industrial and agricultural chemicals.

HIGH-PRESSURE (WH15X, WH20X)A larger diameter impeller with more, shallower vanes will


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PUMP PERFORMANCEThe performance curves reflect standard testing. Pumpmanufacturers typically calculate performance curves

using a pressure gauge and a flow meter connected to thedischarge port. For any anticipated total head, thedischarge capacity can be determined.

Pump performance curves can be found on each modelpage.
http://www.hondapowerequipment.com/pumppics/pumpercon.htmhttp://www.hondapowerequipment.com/pumppics/honpum.htm


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PUMP PERFORMANCE CONSIDERATIONSThe performance curves are useful in selecting

a particular water pump. When a questionregarding the performance of a specific pump

must be answered, refer to the pumpspecifications for the particular model.

Determine how high the pump will sit abovethe water source (static suction head).

Determine how high the discharge end will be

elevated above the pump (static dischargehead). Determine what the discharge capacity(gpm) of the pump must be .

Given the total head (suction + discharge), thedischarge capacity can be estimated by

referring to the performance curve.

Keep in mind, the actual discharge


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SPECIAL CONSIDERATIONSThe total static head is often only considered when

selecting a pump. However, because of frictional losses,this method can often lead to large error, and in many

cases, the pump performance will not meet expectations.

The selection process becomes even more complicatedwhen a nozzle or sprinklers are used.

In order to accurately predict the performance of acentrifugal pump in a specific application, the total headlosses must be considered. These losses include, but arenot limited to: total static head, losses due to pipe size,

length, and material, and losses due to sprinklers or anozzle.


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SUCTION HEAD vs PERFORMANCEMother nature plays an important role by exerting only 14.7 psi on any body of water at sea

level. This limits the suction head of centrifugal pumps to 33.9 feet. However, this would onlybe obtained if we could achieve a perfect vacuum in the pump. In reality, the suction head of

centrifugal pumps is limited to about 26 feet. Pump performance (capacity or pressure) ishighest when the pump is operated close to the water's surface. Increasing the suction head

will DECREASE the discharge head and consequently the discharge capacity of the pump.Most importantly, suction head should be kept to the smallest value possible to reduce the

likelihood of cavitation. Cavitation can also occur if the suction hose is restricted. Never use asuction hose with a smaller diameter than the suction port. Cavitation can quickly damage a

pump.
http://www.hondapowerequipment.com/pumppics/pumdishea.htmhttp://www.hondapowerequipment.com/pumppics/pumdis.htm


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DISCHARGE LENGTH vs PERFORMANCEAs the length of the discharge hose increases, the water comes into contact with more hosesurface. As discussed in hose material, the inner wall of the discharge hose (in contact withthe rushing water) will cause friction to build up. The increase in friction will slow the water,

decreasing the discharge capacity.

Hose/pipe length is considered in Pump Select calculations.
http://www.hondapowerequipment.com/pumppics/pumres.htmhttp://www.hondapowerequipment.com/pumppics/pumdishea.htm


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RESTRICTION vs PERFORMANCERestrictions are like dams to the flow of water. When thewater hits the restriction, only a partial amount of theflowing water will be allowed to pass through. A rule of

thumb is to keep the discharge hose as straight aspossible and avoid reducing the size of the hose whenever

possible. Restrictions will INCREASE the friction andDECREASE the discharge capacity at the end of the pipe.
http://www.hondapowerequipment.com/pumppics/pumelb.htmhttp://www.hondapowerequipment.com/pumppics/pumdislen.htm


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COUPLERS AND VALVESAs valves and couplers are added to lengths of pipe, thesmooth flow of the water is broken up. The turbulence

created around these joints causes an increase in frictionwhich will DECREASE the discharge capacity.
http://www.hondapowerequipment.com/pumppics/pumalt.htmhttp://www.hondapowerequipment.com/pumppics/pumelb.htm


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ALTITUDE vs PERFORMANCE (ATMOSPHERIC LOSSES)Engine performance DECREASES with altitude. The higher thealtitude, the less air there is available to support combustion.

Maximum engine power DECREASES about 3.5% per 1000 feet ofaltitude.

Less air also means there is less air pressure to push on the body ofwater we are trying to draw into the pump. Because there is less airpressure forcing the water into the pump, the maximum available

suction head is DECREASED. The reduction in engine power may alsoresult in a reduced discharge capacity.
http://www.hondapowerequipment.com/pumppics/pumcou.htm


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Figura 23. Esquema de una bomba volumtrica de cilindro
http://images.google.com.bo/imgres?imgurl=http://home.wxs.nl/~brink494/tw_pmp.htg/twpr.gif&imgrefurl=http://home.wxs.nl/~brink494/tw_pmp_e.htm&h=311&w=556&sz=22&tbnid=6A7rql1rab0J:&tbnh=73&tbnw=131&hl=es&start=2&prev=/images%3Fq%3Dbomba%2Bde%2Bengranajes%26svnum%3D10%26hl%3Des%26lr%3D%26sa%3DGhttp://images.google.com.bo/imgres?imgurl=http://home.wxs.nl/~brink494/tw_pmp3.htg/tandwiel3.jpg&imgrefurl=http://home.wxs.nl/~brink494/twpmp3_e.htm&h=336&w=498&sz=64&tbnid=JeFdd_FDC6QJ:&tbnh=85&tbnw=127&hl=es&start=1&prev=/images%3Fq%3Dbomba%2Bde%2Bengranajes%26svnum%3D10%26hl%3Des%26lr%3D%26sa%3DG


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