pump basics

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Centrifugal Pump

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Centrifugal Pumps

The term “centrifugal pump” has been used to describe a wide variety of pumping applications and designs throughout the years.

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Centrifugal Pump

The REDA centrifugal pump

is a multistage pump,

containing a selected

number (application

dependent) of impellers

equipped with vanes, inside

a closely fitted diffuser,

located in series an axial

shaft, driven by the electrical

motor.

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Centrifugal Pump

A centrifugal pump creates pressure by the rotation of a series of vanes in an impeller.

The impeller’s job is to transfer energy by rotation to the liquid passing through it, thus raising the kinetic energy.

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Centrifugal Pump

The diffuser section then converts this energy

to potential energy, raising the discharge

pressure.

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Centrifugal Pump

From there, the rotation of

the high-speed impeller

throws the liquid into the

diffuser.

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Centrifugal PumpsEach "stage" consists of an

impeller and a diffuser. The

impeller takes the fluid and

imparts kinetic energy to it. The

diffuser converts this kinetic

energy into potential energy

(head or pressure).

Upthrust Washer

Impeller

Down Thrust Washer

Diffuser

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• Curves for centrifugal

pumps are normally

shown as flow versus

head in feet, meters,

or some other

consistent unit.

Head: The height

to which the pump

will "lift" the fluid

HEAD

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0 2000010000 30000

20000

10000

0

Tota

l D

ynam

ic H

ea

d -

Feet

15000

5000

Flow Rate - BPD (60 Hz)

Maximum Head-Capacity

5.5" Casing

7" Casing

4.5" Casing

REDARev. B

SN2600 60 HZ / 3500 RPM Pump Performance Curve 538 Series - 1 Stage(s) - Sp. Gr. 1.00Optimum Operating RangeNominal Housing DiameterShaft DiameterShaft Cross Sectional AreaMinimum Casing Size

1600 - 32005.38

0.8750.6017.000

bpd inches inches in2 inches

Shaft Brake Horsepower Limit:

Housing Burst Pressure Limit:

StandardHigh StrengthStandardButtressWelded

256410N/A

60006000

Hp Hp psi psi psi

REDARev. B

SN2600 60 HZ / 3500 RPM Pump Performance Curve 538 Series - 1 Stage(s) - Sp. Gr. 1.00Optimum Operating RangeNominal Housing DiameterShaft DiameterShaft Cross Sectional AreaMinimum Casing Size

1600 - 32005.38

0.8750.6017.000

bpd inches inches in2 inches

Shaft Brake Horsepower Limit:

Housing Burst Pressure Limit:

StandardHigh StrengthStandardButtressWelded

256410N/A

60006000

Hp Hp psi psi psi

EffHpFeet

60%

B.E.P.Q = 2581H = 46.75P = 1.31E = 68.09

60 3.00

Schlu40%

50%

40

50

2.00

2.50

mberger Private

30%30 1.50

10%

20%

10

20

0.50

1.00

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000Capacity - Barrels per Day

• From this curve we can determine the head produced, brake

horsepower required and hydraulic efficiency at any flow rate.

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Impeller Thrust

Cross-Section of a Typical Impeller

An Impeller has three forces acting on it.

The sum of these three forces is the total

thrust.

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Pressure: F = Press x Area

Low Pressure

High Pressure

Impeller ThrustGravity: F=mA

Momentum: F = d(mass) x velocity + d(velocity) x mass

d(time) d(time)

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Pressure: By using a "balance ring" between the impeller and

diffuser and drilling "balance holes" in the upper

impeller skirt, we can recirculate lower pressure

fluid over the majority of the upper surface.

Balance

RingBalance

Hole

Low Pressure Fluid

Low Pressure

High Pressure

Impeller Thrust

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Efficiency

Flow Rate

% H

ors

e P

ow

er

0%

0%

100%

100%

Mechanical

Natural Leakage

Recirculation

from Impeller

Shape

Hydraulic

LossPump Output

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Pump Descriptions and Names

The series designations are defined as:

Type Series Outside

Diameter

Minimum

Casing SizeA 338 3.38” 4 ½”

D 400 4.00” 5 ½”

G 540 5.13” 6 5/8”

S 538 5.38” 7”

H 562 5.63” 7”

J 675 6.75” 8 5/8”

L 738 7.25” 9 5/8”

M 862 8.63” 10 ¾”

N 950 9.5” 11 ¾”

950 10.00” 11 ¾”

P 1125 11.25” 13 3/8”

DN 1300

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Pump Descriptions and Names:

• N = NiResist

• R = 5530

• V = Type 4

• Many other letters will be used to discribe

the pump…

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Pump Nomenclature:Frequently Used Terms

Abbreviation Definition

ARZ Abrasion Resistant: Zirconia bushings and sleeves

ARZ-S Abrasion Resistant: Silicon Carbide sleeves

ARZ-SS Abrasion Resistant: Silicon Carbide bushing and sleeves

ARZ-T Abrasion Resistant: Tungsten-Carbide sleeves

ARZ-TT Abrasion Resistant: Tungsten-Carbide bushings and sleeves

ARZ-ZS Abrasion Resistant: Zirconia bushing bushings and Silicon sleeves

ARZ-ZT Abrasion Resistant: Zirconia bushing bushings and Tungsten sleeves

C Compression

CT Center Tandem

C-CT Compression-Center Tandem

C-LT Compression-Lower Tandem

CR Compression Ring

CR-CT Compression Ring-Center Tandem

CR-LT Compression Ring-Lower Tandem

ES Enhanced Stability

FL Floater

FL-CT Floater-Center Tandem

FL-LT Floater-Lower Tandem

FL-S Floater-Single section

HB Hydraulic Balance

HSG Housing

S Single

SS Stainless Steel

SS H and B Stainless Steel Head and Base

CS Carbon Steel

M-Trim Monel Trim

Rloy Redaloy

SLB Self Lubricating bearings (Graphalloy)

HSS High Strength Shaft

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Pump naming conventions

DN1400 indicates:

D = 400 series, therefore, 4.0” in diameter

N = the material of the stage, in this case ni-

resist.

1400 = the best efficiency flow rate

(60 Hz : 3500 RPM) in barrels per day.

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Pump Construction

There are two types of pump stage

construction for ESP oil field applications:

Floater - Type

Compression - Type

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2 Types of Stage Construction

Pump

Down

Thrust

Carried

here

Impeller

Thrust

Compression

Floater

Protector

Thrust

Bearing

Motor

Thrust

Bearing

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"Compression" Pumps

In a compression pump, all the impellers are rigidly fixed to

the shaft so that if an impeller wants to move up or down, it

will take the shaft with it.

The impeller is normally sitting down on its lower diffuser

during assembly due to gravity. Because of this, the pump

shaft is "raised" with shims in the coupling so that the impeller

is not allowed to touch the diffuser after final assembly. This

allows all thrust developed in the pump shaft to be transferred

to the protector shaft directly.

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There is a small amount of free play in the

coupling such that the pump shaft can fall

down to where the impellers ride directly on

the lower diffusers or on the downthrust

washers if available.

Impeller is in full down

position

Pump

Shimming

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Add shims so the impeller is

lifted slightly off diffuser.

Shims placed in

coupling to raise

the shaft

Pump

Shimming

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Why use Compression Pumps?

• Some stages generate too much thrust to be handled by a thrust

washer in the stage.

• Some fluids (e.g. liquid propane) do not have enough lubricity to

properly lubricate a thrust washer.

• If abrasives or corrosives are present, it may be beneficial to handle

the thrust in an area lubricated by motor oil rather than well fluid.

• Occasionally in very gassy wells, the flow volume changes so

drastically within the pump that parts of a floater pump could be in

very severe thrust while others are not so a compression pump could

be one alternative.

• Since all the thrust is handled in the protector, as long as the

protector has a great enough capacity, the pump operating range can

be extended over a much wider area without any increased wear or

reduced life.

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Centrifugal Pumps

A radial flow

(pancake) impeller

has vane angels at

close to 90 degree,

and therefore, are

usually found in

pump ranges for

lower flow rates.

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Centrifugal Pumps

A mixed flow impeller

has vane angels at

close to 45 degree,

and therefore, are

usually found in

pump ranges for

higher flow rates.