About Centrifugal Pumps and Centrifugal Pump Manufacturers,
Including: 12 Volt Pump, Axial Flow Pumps, Chemical
Pumps, Electric Pump, Jet Pump, Self Priming Pumps, Submersible
Pumps, Sump
Pumps, Trash
Pumps, Vertical Pumps, Water
Pumps & Well
Pumps.
Centrifugal pumps are simple devices consisting of
only a few parts that are designed to move liquids. All centrifugal pump
manufacturers use an impeller and a stationary volute, also referred
to as the casing or diffuser, that houses the impeller. Centrifugal pumps
use these components to create the necessary force to move the liquid
through the pump and out of the discharge outlet. The impeller moves
the liquid away from the eye to the vane tips of the impeller, where
the high pressure is located, and from the outer edge of the casing.
The purpose of the volute is to take the velocity (or kinetic energy)
of the liquid and change it to pressure force through the increasing
size of its spiral shape. As the size of the volute increases, it acts
progressively to reduce the speed and increase the pressure of the liquid.
The process of centrifugal pumping works by converting mechanical energy
into kinetic energy, changing the pressure force. Mechanical force powers
the shaft to move the impeller. The impeller then uses vanes to impart
kinetic energy or velocity to the liquid inside the casing. This initial
movement of the liquid, called priming, purges the air from the casing.
The liquid enters the centrifugal pumps at the eye of the impeller. A
partial vacuum, or low pressure point, at the eye of the impeller is
created both by the purging of the air and by the liquid leaving the
eye of the impeller
Centrifugal pump manufacturers design products that are ideal devices
for moving fluids from one place to another. These centrifugal pumps
deliver fluid at a uniform pressure without pulsations or shocks. They
are able to handle liquids with high quantities of solids. Since centrifugal
pumps have a simple construction, they have a relatively low cost, as
well as low maintenance costs. However, centrifugal pumps cannot operate
at high heads, are subject to air binding and usually requiring priming.
Centrifugal pumps operate efficiently in a narrow range of conditions
and do not handle highly viscous fluid well.
Centrifugal pumps are typically used to pump water, but they are also
used for moving oil and gas. Centrifugal pump manufacturers make the
most commonly used pump in the chemical industry. Other industries in
which they find use include refineries, nuclear power plants and the
hydrocarbon and petrochemical industries. Some centrifugal pumps are
designed especially to handle corrosive liquids and slurries and solids,
which are often present in corrosive environments. For private use, typical
applications include well systems and low flow irrigation. Specifically
designed centrifugal pumps are utilized to move what is considered "trash
water," such as sewage.
Types of Centrifugal Pumps
- have a vertical shaft with a bottom suction, and the totally submerged
propeller is mounted near the bottom of the shaft and enclosed in
a
bowl. Axial flow pumps, used mainly for clear water service and wet
well installations, develop pressure by the lifting or propelling
action
of the impeller vanes on the liquid.
- are
made of corrosive-resistant materials.
- are directly connected to a power unit but do not have any less gearing
or shafting.
- are self-priming and capable
of handling clear water and water containing small particulate matter
up to .25" in
diameter. Some dewatering pumps are completely submersible and can
operate from any position,
including upside down.
- are a type of radial flow pump in which the fluid enters the impeller
from both sides. Due to the extending of the shaft into the suction
passage, double suction pumps are limited to pumping clear liquids.
- are mounted on the surface and use
an "ejector" (venturi)
mechanism to enhance suction ability. In a "deep well jet pump," the
ejector is down in the well to assist the pump in overcoming the limitations
of suction.
- are designed with wide unblocked passageways and are an intermediate
pump between radial and axial flow pumps. Mixed flow pumps develop
the
pressure partially with centrifugal force and partially with the lift
of the impeller vanes on the liquid.
- ,
which can be either horizontal or vertical, consist of two or more
pumps of similar capacity that discharge into each other in a series.
Progressively
the pumps develop a total head, the sum of the heads that each pump
has developed. A common shaft with several impellers, each with its
own volute, is rotated by a power supply, building up pressure in
stages.
- take in liquid through the center of the impeller and move it out along
the impeller blades at a 90-degree angle to the pump shaft. Radial
flow
pumps develop the pressure only with centrifugal force.
- are designed to permit uninterrupted water flow by automatically removing
air from the suction line and replenishing itself with water from
the
pump.
- have smaller openings and cannot handle as great of an amount of solids
or large solids as trash pumps can. There is no industry standard
dividing
semi-trash pumps from trash pumps, so both may be referred to simply
as trash pumps.
- are a type of radial flow pump in which the fluid enters the impeller
from one side, and the shaft does not reach into the suction passage.
Single-end suction pumps are used in applications where there are
large
solids, such as rags and trash, that would normally clog the pump.
- are designed to run inside the water source being pumped, eliminating
the suction lift limitations common with other types of pumps. Suction
pumps are ideal for private use, such as in well systems or irrigation.
- are used
to pump water or other fluids from low-laying surfaces.
- are heavy-duty centrifugal pumps that are designed to pump hundreds
or even thousands of gallons of water per minute, which contains
large
solids, such as twigs, sand, mud, soft solids and trash. Trash pumps
have deeper impeller vanes, incorporated with a larger volute discharge
opening, and are used in such applications as construction and agricultural
sites.
- turn the shaft and impeller at two different rpm levels with a two-speed
motor, allowing for optional pump capacity.
- are designed to have only the casing and the impeller submerged in
the pumpage for priming and the support bearings for the rotating
element
in a dry environment. Vertical cantilever pumps have no throttle or
bumper bushings or any rings at the impeller or submerged below the
maximum normal water level, and they are used in applications, such
as a sump or tank, in which it is necessary not to have a bearing
in
the pumpage.
- are used for deep-well pumping, as their motors are at ground level
and their pumps at or near the surface of the water.
- are inefficiently designed pumps
in which the impeller is recessed into the volute. However, vortex
pumps are practical in applications
that
require pumping of excessive solids.
- use
an electric motor to move water.
- extract
water from wells.
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Centrifugal Pumps Terms
-
A circumstance in which a centrifugal body is so full of air that a vacuum
can no longer be formed. Without vacuum, water cannot flow into the pump.
- The force
applied by the atmosphere to the surface of the earth. Atmospheric pressure,
the standard of which is 14.7 lbs per square inch, affects the operation
of a pump.
- A term describing
how much water a pump can process. Capacity is typically articulated as
gallons per hour (gph) or gallons per minute (gpm).
- An undesirable
condition in which vacuum pockets form within the pump. The air pockets
eventually implode under pressure, resulting in the pitting of the impeller
and volute surfaces.
- The force
that causes a substance to move away from its center of rotation.
- An apparatus in a discharge or suction line that permits flow
in only one direction so as to prevent reverse flow and isolate the material
being pumped.
- The removal of
unwanted dirty or clear water containing no hazardous materials.
- A stationary casing,
like a volute, that houses the moving impeller. Diffusers are compact
in design, enabling the pump to create higher pressure heads.
- A collapsible
hose that moves the discharged water from the pump.
- Also called
the "outlet," it is the point at which the discharge pipe
or hose is connected to the pump.
- Detachable plugs
for draining water from the pump when it is inactive.
- Acting by motion,
not weight, in contrast to static.
- The head or pressure
force against which the pump operates.
- Also
known as "total suction head," it is the combination of the
static suction lift and the suction friction loss in the suction line.
- Partially or completely
treated wastewater or other liquid that flows out of a septic tank or
treatment unit.
- Rubber molded
around a steel weight that seals off the inlet or outlet, preventing water
from either entering or exiting the pump at the wrong time.
- The required amount
of gallons per minute (gpm) of pump flow. Flow can also be expressed in
gallons per hour (gph) and in million gallons per day (mdg).
- The measure of the pressure
or force exerted by a fluid in a hydraulic system. Also, the height of
fluid above any point, taking into account losses or gains in pressure
due to gravity and friction as water travels through a system, measured
in lbs per square inch (psi) or feet of water.
- A rotating disk with
vanes of varying amounts attached to the "r" drive shaft that
creates centrifugal force within the pump casing of a centrifugal pump.
Impellers can be open or closed.
- The center of
the impeller and the point at which fluid flows into the impeller.
- Pump components
located on the impeller between the eye and the discharge side of the
impeller. Impeller vanes direct the flow of the liquid to the outside
diameter of the impeller.
- The flow, or the rate
of flow, into a pump.
- A device that
forms a seal between the pump and the engine or motor and prevents water
from getting into the engine or motor.
- A measure of the absolute pressure of the liquid at the inlet
of the pump.
- Allowing the pump to
disperse all air from the influent line of a circulating system by causing
fluid to start flowing once again. Priming the pump is usually accomplished
by either manually filing the volute or turning the pump on.
- The body or casing
of a pump, which may be made of plastic, cast-iron, stainless steel or
aluminum.
- Rubber
vibration-dampening devices that are mounted on the engine to prevent
the pump from "walking away."
- Acting by weight not
motion, in contrast to dynamic.
- A plastic
mesh basket that traps debris to prevent its reaching the impeller. Strainer
baskets are located in the strainer pot.
- The housing of
the strainer basket that is located on the influent side of the pump.
Strainer pots serve as a priming chamber.
- A reinforced
hose through which water flows into the suction end of a pump.
- A type
of cavitation resulting from the small size of the impeller or low cutwater
clearance.
- The act of removing air
or gas from a system. Stuffing boxes in vertical pumps must be vented
to prevent the seal faces from running dry.
- The resistance to
flow of a liquid at a particular temperature. High viscosity liquids,
such as motor oil, are thick and tend to flow slower than water, a low
viscosity liquid.
- Stationary casing of
a centrifugal pump that separates air and water and in which the impeller
rotates. Volutes are spiral-shaped in order to facilitate the partial
conversion of the velocity (kinetic) energy into pressure head as the
water leaves the impeller.
- Creates a
"whirlpool effect" that can cause air to be drawn into the
suction of the pump.
- A small opening
located on the underside of the pump at which point the engine joins the
pump. Weep holes provide the means to quick detection of a leak before
water seeps into the oil sump of the engine.
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