| Ten
Reasons to buy OEM Pump Parts |
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You get the parts that's made to fit your pump and
not a par that is "almost alright" |
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The parts are manufactured, under rigid quality
control techniques, to original design specifications
and tolerances. |
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The materials are properly developed to specifications
that ensure consistent quality. |
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The parts, pump, and your application are backed
by the company's knowledgeable sales staff and technical
support personnel. |
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Critical parts are hydraulically tested to ensure
trustworthy application. |
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It allows you to forge a strong relationship with
the OEM for the best all-round service. |
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It allows the OEM to develop and maintain a database
on the equipment, which can be used for troubleshooting,
future upgrades, and accurate re-ordering of parts. |
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By supporting the OEMs, you enable them to conduct
more extensive research and development, thereby
improving their products, customer service and pricing
for yourself. |
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Using non-OEM parts can void the pump warranty. |
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Using non-OEM parts can, in critical applications,
pose a safety hazard. |
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Centrifugal
pump is a velocity machine. Peripheral Speed
(or) Tip Velocity =  DN/60
m/sec. |
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Change
in impeller dia will change tip speed |
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Velocities
in the pump impeller and casing for similar
points on the H-Q curve will vary directly
in the same proportion |
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Therefore,
Capacity - direct function velocity - vary
directly as impeller dia ratio |
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The
total head - Function of square of tip speed
- will vary square of the dia ratio |
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As
power consumption varies as the product of
capacity and head, power will vary as the
cube of the diameter ratio:
BHP = (QxHxSG)/(367 x 0.746 x
) |
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Since
it is the tip speed of the impeller that determines
head and capacity of the pump, obviously it
is immaterial whether the tip speed is changed
by cutting down the impeller diameter (or)
the pump speed. |
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| Should
Suction or Discharge be Throttled ? |
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Centrifugal
pumps will deliver the flow corresponding
to the intersection of H-Q curve and system
head |
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System
Head Curve - static head + friction losses |
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Static
Head - 130 M and Friction Loss 30 M at 160
cu.m. assumed |
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H-Q
Curve at 130 cu.m. well in excess of system
head curve |
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Artificial
friction losses by throttling 130 cu.m. and
176 m. power consumption reduced from 77.5
to 70 HP |
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Suction
Throttling - will change H-Q curve through
cavitation and operation in the so-called
break |
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Pump
efficiency is seriously affected |
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Erosion
and premature destruction - most important
of the ill effects. |
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For
permanent reduction - cut down impeller (7%)
- so that H-Q curve passes through 130 cu.m.
and 150 m, to intersect present system head
curve. |
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Power
consumption - 59 HP as compared to with 70
HP obtained by throttling. |
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| Higher
Ss (Specific speed) Value |
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| Large
Impeller Eye Diameter |
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| Higher
Capacity at Suction Recirculation |
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| Narrower
Range of Trouble Free Operation |
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Pumping is the addition of kinetic
and potential energy to a liquid for the purpose of
moving it from one point to another. This energy will
cause the liquid to do work, such as flowing through
a pipeline or rising to a higher level.
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A Centrifugal Pump transfers mechanical
energy form a rotating impeller into the kinetic and
potential energy required. For a given pump operating
at a certain speed and handling a certain volume of
liquid, the energy applied and transferred to the liquid
is same, for any liquid regardless of density. The pump
head or energy in Kg/Cm2 must therefore be expresses
in m.
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Within Pumping system itself, we must
remember that
1. Head can be measured in various units, such as in
m of liquid, pressure in Kg/Cm2, mm of mercury etc.
2. Pressure and head readings can be in gauge or Absolute
Units.
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A column of cold water 10 m high will
produce a pressure of 1 Kg/Cm2. Thus, for water at ordinary
ambient temperatures, any pressure calculated in Kg/Cm2
can be converted into an equivalent head in m of water
by multiplying by 10. for liquids other than cold water,
the column of liquid equivalent to 1 Kg/Cm2 can be calculated
by dividing 10 by the specific gravity of the liquid.
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1
ATM = 1.013 BAR = 1.033 Kg/Cm2
1 ATM = 10.33 m column of cold water
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| therefore
10.33 m column of cold water |
=
1.033 Kg/Cm2 |
| therefore
Pressure in Kg/Cm2 |
= (1.033/10.33)
x Head in m x specific gravity |
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=
(Head in m /10) x specific gravity |
| therefore
Head in m |
=
( Pressure in Kg/Cm2/specific gravity
) x 10 |
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Still some of our users are getting
confused between the relationship of Head MWC and Head
MLC. As long as there are no correction factors involved
like viscosity, slurry, etc., The performance of a centrifugal
pump will be exactly similar for both water and liquid.
If the total differential head is specified in terms
of pressure like Kg/Cm2, PSI, etc., the specified pressure
value is to be divided by the specific gravity of the
liquid being pumped, then the correction factors are
to be applied for converting into metres.
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| If
the sum of lift, losses, vapour pressure, and NPSH
® exceeds Barometric Pressure, then the system
needs positive suction head. |
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A pump operating in a system must develop
a total head, which is made up of several components.
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| Static
Head |
Static
Head |
| Difference
in Pressure |
Static Head |
| Friction
loss in pipes, valves etc. |
Friction Loss |
| Entrance
and Exit losses |
Friction
Loss |
| Difference
in Velocity Heads |
Friction
Loss |
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If the sum of total static head and
of the frictional losses for a series of assumed flows
is plotted against flow, the resulting curve is called
the system head curve.
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Superimpose the H-Q curve of the pump
on the system head curve and the intersection will indicate
the flow that will be delivered to the system.
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