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Calculating Radial Loads

Calculating Radial Loads on impellers in a volute

type casing.

CP-12

Total suction head psig = 25.000

Total suction head converted to psia = 39.700

sp. gr. = 0.765

Total suction head converted to feet of liquid, absolute = 119.827

Total discharge head psig = 432

Total discharge head converted to psia = 446.7

Total discharge head converted to feet of liquid, absolute = 1304

H = total head at Q gpm, in feet 1184

D2 = O.D. of impeller, in inches 11.875

B2 = width of impeller at O.D., in inches 1

Q = capacity, in gpm, at which radial thrust is to 432

Qn = capacity, in gpm, at best efficiency of pump 950

N = rotative speed, in rpm's 3560

hsv = net positive suction head required by 26

maximum diameter impeller at best

efficiency, in feet

K = radial thrust factor at shutoff, (from sheet 3) 0.18

Kq = capacity factor 0.36903

n = 0.58436

Ns = specific speed of pump 367

S = suction specific speed, ideal less than 12,000 9530higher values indicate less NPSH requirements

P = Resultant radial force, in pounds 309

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Calculating Radial Loads

psig

psia

feet

psig

psia

feet

feet **used to calculate Ns

*used to calculate Nsss (S) and **Ns

*used to calculate Nsss (S) and **Ns

*used to calculate Nsss (S)

where: Kq = 1 - (Q/Qn)(power n)

where: n = 0.7+2.6((Ns-500)/3000)

where: Ns = NQ(power.5/H (power.75)

where: S = NQ(power.5)/hsv(power.75)

where: P = Kq x K x (H x sp gr/2.31) x D2 x B2

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First Critical Speed

Estimating first critical speed,

overhung or centerhung

CP-12 impeller = 35 lbs.

w = weight of mass (impeller and/or impeller and loading) 50 pounds

d = shaft diameter 1.875 inches

L = shaft length 11.75 L = length of shafts = distance between bearings 9.375 inches

Y = maximum deflection, at end if (overhung) 0.0015 Y = WL (power3)/3EI

Y = maximum deflection, at center if (center hung) 0.0000 Y = WL (power3)/48EI

E = modulus of elasticity, 30,000,000 psi for steel 30,000,000 E = 30,000,000

I = moment of inertia of the shaft, in. (power 4) 0.607 I = pi*d(power4)/64

Ks = spring constant of the shaft if (overhung) 33659 Ks = 3EI/L(power3)

Ks = spring constant of the shaft if (center hung) 1060288 Ks = 48EI/L(power3)

M = mass divided by gravity 0.1295 M = weight / acceleration of gravity

w = first critical speed in rpm's if (overhung) 4868 w =(square root)Ks/M(60/2pi)

w = first critical speed in rpm's if (center hung) 27321 w =(square root)Ks/M(60/2pi)

Motor speed = 3560 + 15% = 4094 cpmMotor speed = 3560 - 15% = 3026 cpm

At 534 GPM CPM = 3873 109% of motor speed

To keep the bolt from breaking

At 829 GPM shaft deflection is .0015"

To keep the seal from leaking

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K - Radial Thrust Factor

0.125

0.175

0.225

0.250

0.280

0.300

0.3250.340

0.350

0.365

0.370

0.375

0.375

0.375

0.375

0.000

0.050

0.100

0.150

0.200

0.2500.300

0.350

0.400

K

-RadialThrustFactor

400 1000 2000 3000 4000Specific Speed Ns

Chart

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K - Radial Thrust Factor

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Test for Vaporization

Test for Vaporization

CP-12

Total suction head psig = 12.000 psig

Total suction head converted to psia = 26.700 psia

sp. gr. = 0.765

Total suction head converted to feet of liquid, absolute = 80.589 feetRequired NPSH in feet = 9.500 feet

Pressure experienced by the fluid particle

in the pump suction, absolute = 71.089 feet

Vapor pressure of product, absolute = 0.500 psia

Vapor pressure converted to feet of liquid, absolute = 1.509 feet

Available NPSH in feet = 79.079 feet

If less than required vaporization is occurring and suction

head should be increased.

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Bearing Load

Calculating radial loads on bearings

CP-12

w = weight of mass (impeller and/or impeller and loading) 79.00

L = shaft length 11.75

s = distance between bearings 9.38

R1 = load at bearing 1, in pounds 99.01R2 = load at bearing 2, in pounds 178.01




R1 = load at bearing 1, in pounds 62.67

R2 = load at bearing 2, in pounds 112.67




R1 = load at bearing 1, in pounds 43.87R2 = load at bearing 2, in pounds 78.87

At 534 GPM w = 79

At 829 GPM w = 50

At 950 w = 35

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Bearing Load

pounds

L = length of shaft from first bearing to center of mass

inches

R1 = Pa\sR2 = P(a+s)/s

pounds


inches

R1 = Pa\s

R2 = P(a+s)/s

pounds


inches

R1 = Pa\sR2 = P(a+s)/s

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Rotor Stiffness

Calculating Rotor Stiffness

CP-12

L = shaft length (overhung portion) 11.75

d = shaft diameter 1.875

L3D4 = measure of rotor stiffness 131


d = shaft diameter 1.918



d = shaft diameter 2


The lower the L3D4 the less the shaft deflection

seals are prone to leak with deflection of .0015

ANSI pumps have L3D4 ratios of 20 - 120

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Rotor Stiffness

inches

inches

L3D4 = Shaft length (power 3)/shaft diameter (power 4)

inches

inches


inches

inches


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BPD to GPM

To convert BPD to GPM To convert GPM to BPD

BPD = 11000 GPM = 100

Converted to GPM = 321 Converted to BPD = 4200

BPD = 4000 GPM = 200


BPD = 6000 GPM = 300


BPD = 8000 GPM = 400


BPD = 10000 GPM = 500


BPD = 12000 GPM = 600


BPD = 14000 GPM = 700


BPD = 16000 GPM = 200Converted to GPM = 467 Converted to BPD = 8400

BPD = 18000 GPM = 300


BPD = 20000 GPM = 400


BPD = 22000 GPM = 500


BPD = 24000 GPM = 600

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BPD to GPM


BPD = 26000 GPM = 700


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Convert Feet of Liquid to psig

To convert feet to psi To convert psi to feet

Feet of head = 40.000 psig = 345.000

sp. gr. = 0.700 sp. gr. = 0.819

Converted to PSI = 12.126 Converted to feet of head = 972.656

Feet of head = 200.000 psig = 100.000

sp. gr. = 0.765 sp. gr. = 0.819


Feet of head = 300.000 psig = 315.000

sp. gr. = 0.765 sp. gr. = 0.819


Feet of head = 400.000 psig = 245.000

sp. gr. = 0.765 sp. gr. = 0.819


Feet of head = 500.000 psig = 84.000

sp. gr. = 0.765 sp. gr. = 0.819


Feet of head = 600.000 psig = 175.000

sp. gr. = 0.765 sp. gr. = 0.765Converted to PSI = 198.787 Converted to feet of head = 528.203

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Aprox. Flow Through Orifice

To Aproximate the flow through an orifice

(water)

Q=AV

Q= The flow in cubic feet per second (ft3/sec.)

A= The area of the orifice in square feet (ft2)

V= The velocity of the liquid in feet per second (ft/sec.)

Q=AVK

h=V(2)/2g or V=su.rt 2gh or V=8.02 sq.rt.h

g=32.2 ft/sec(2)

h= Head across the orifice

High pressure side = 285 psig

Low pressure side = 116 psig

Differiential psig = 169.000 psig

sp. gr. = 0.523

Differiential head = 746.120 feet

Differiential head = 746.120 Feet of LiquidArea = 0.14 Square Inches

K factor = 0.62

Flow = 59.274 GPM's

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To Estimate Force of Imbalance

To estimate the force of imbalance

Weight of component = 30 Pounds

Speed = 3600 Rpm's

Balance tolerance 4w/n = 0.0333 Ounce inches

Balance tolerance 4w/n = 0.9451 Gram inches

50% for symmetrical weight = 0.4725 Gram inchesFor non symmetrical rotors the individual journal load

must be calculated

Acceptable weight of imbalance = 0.4725 Gram inches

Weight of imbalance in grams converted to pounds = 0.0010 Pound inches

Acceleration of gravity = 386 Inches per second per second

Radius of gyration of imbalance = 1 Inches

Velocity = 22619.5 Inches per minute

Velocity = 377.0 Inches per second

Acceleration = 142122.3 Inches per second per second

Force = 0.4 Pounds

Force should be less that 5% of component weight

mm per second 2.5 mm per second

convert to inches per second 0.098425 Inches per second

Balance quality grade

Vibration

velocity in Rotor types

G

mm per

second General examples

Crankshaft drives of large Diesel engines

Complete engines for trucks and locomotives

G 40 40

Crankshaft drives for engines of trucks and

locomotives

Parts of crushing machinery

Parts of agricultural machinery

Fly-wheels

Fans

Aircraft gas turbine rotors

Electrical armatures

Process plant machinery

Pump impellers

Machine-tool drives

Turbo compressors

Small electric armatures

Turbine-driven pumps

Grinding machine drives

Textile bobbins

Automotive turbochargers

Gyroscopes

Disk-drives

Spindles for high-precision applications

ISO Grade 2.5 at 3600 RPM's

Balance quality grades are standardized in ISO 1940.

G 100

G 16

G 6.3

100

16

6.3

G 2.5

G 1

G 0.4

The smaller the number, the smoother the operation

1

0.4

2.5

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To Estimate Force of Imbalance

Acceptable weight of imbalance = 8 kg

Acceleration of gravity = 980.44 centimeters per second per second

Radius of gyration = 1 centimeter

Rpm's = 3600 revolutions per minute

Velocity = 22619.4671 centimeters per minute

Velocity = 376.991118 centimeters per secondAcceleration = 142122.303 centimeters per second per second

Force = 11.596614 kilograms

Force = 25.6 pounds

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Flow and Critical

CP-12 flow and its affect on the first critical of the pump shaft

GPM's BPD Resultant Load After Weight of Total Load First Critical % of Motor

Radial Loading Balancing Impeller of Pump Shaft Speed

Away 80% CPM's 3560

0 0 505 101 35 136 2952 83% Acceptable

100 3429 370 74 35 109 3297 93% Bad

200 6857 340 68 35 103 3392 95% Bad

300 10286 308 62 35 97 3495 98% Really Bad

400 13714 274 55 35 90 3628 102% Really Bad

500 17143 235 47 35 82 3801 107% Bad

600 20571 192 38 35 73 4029 113% Acceptable

700 24000 145 29 35 64 4303 121% Acceptable

800 27429 92 18 35 53 4728 133% Acceptable

900 30857 32 6 35 41 5376 151% Acceptable

950 32571 0 0 35 35 5818 163% Acceptable

1000 34286 34 7 35 42 5311 149% Acceptable

1100 37714 108 22 35 57 4559 128% Acceptable

1200 41143 190 38 35 73 4029 113% Acceptable

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Indicator Reverse Alignment

Turbex, Inc. 281-485-8255 Pump # KC-1

Date = August 26, 2013

Time = 6:25 AM

Button to Button = 16

Front foot to 1st. Button = 11

Rear foot to front foot = 32

Movable to fixed = 0 Fixed to movable = 0

Left & right of fixed = 0 RIM 0 Left and right of movable = 0 RIM 0

Movable to fixed = -6 Fixed to movable = 20

If plus add shims TAN of

Front shim change = 15 Ver. 0.00063 Misalignment fixed end Bad

Rear shim change = 29 Hor. 0.00000 Misalignment fixed end Good

If plus move to the right 0.00050 Acceptable to 3600 RPM's

Front lateral move = 0 Ver. -0.00019 Misalignment movable end Good

Rear lateral move = 0 Hor. 0.00000 Misalignment movable end Good

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Rim and Face alignment

Turbex, Inc. 281-485-8255 Pump # P-106-A

Date = August 26, 2013

Flex plane seperation = 7 Time = 6:25 AM

Sweep = 4.5

Front foot to face = 20

Rear foot to face = 34

Movable to fixed = 8 Movable to fixed = -2

Left & right of fixed = 4 RIM 4 Left & right of fixed = -1 FACE -1

Movable to fixed = 0 Movable to fixed = 0

If plus add shims TAN of

Front shim change = 13 Ver. 0.00029 Misalignment face Good

Rear shim change = 19 Hor. 0.00000 Misalignment face Good

If plus move to the right 0.00050 Acceptable to 3600 RPM's

Front lateral move = 0 Ver. -0.00057 Misalignment offset Bad

Rear lateral move = 0 Hor. 0.00000 Misalignment offset Good

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