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~ KSB

KSB Aktiengesellschaft engages in the manufacture, marketing and sale of pumps and valves and ranks as a world leader in

this field. KSB's manufacturing programme covers an extensive range

of products for the water supply sector, power stations, marine and offshore applications, building services as well as process and environmental engineering.

KSB employs around 10.000 people worldwide and is repre­ sented in almost every country of the globe through more than 100 factories, agencies and representatives.

© Copyright by KSB

2

Contents Symbols, Units and Designations

Page 4

2

Design

4

2.1 2.2 2.3 2.4 2.5 2.6 2.6.1 2.6.2 2.7 2.8 2.9 2.10

Pump Capacity Pump Head System Head Speed Selecting the Pump Size Calculating the Power Consumption Pump Power Input Caiculating the Drive Rating System Characteristic (Piping Characteristic) Operating Point Parallel Operation of Centrifugal Pumps

4 4 4 4 6 6 6 6 6 7 7 7

3

Suction Characteristics

8

3.1 3.2

NPSH Required NPSH Available

8 8

4

Pressure Losses Pv

9

4.1 4.2 4.3

Head Losses H, in Straight Pipes

Pump Characteristic Curve

Page 8

General

8.1

National and International Standards for

8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9

Centrifugal Pumps Shaft Deflection Improving the NPSH Requirement Impeller Types Pump Types Pump Installation Arrangements Pump Sump Contiguration Suction Pipe Layout Shaft Couplings

22 24 24 25 26 27 28 28 30

9

Technical Data

31

9.1 9.2 9.3

Vapour pressure Po and Density p of Water Vapour pressure Po of Various Liquids

31 32

16

Density p of Various Liquids at Atmospheric Pressure g.4 Extract of Main Legal Units for Centrifugal Pumps 9.5 Conversion of British and U.S. Units 9.6 Graph for Calculating Flow Velocity v 9.7 Graph for Calculating Velocity Head v'/2 g 9.8 Graph for Calculating Velocity Head Differential I!. v'/2 g 9.9 Graph for Calculating Head Losses H, 9.10 Graph for Calculating Conversion Factors fa,w, fH,w and fTI,w for Viscous Liquids 9.11 Graph for Calculating Conversion Factors fo,l

5.1 Changing the Speed 5.2 Trimming the Impellers

16 16

9.12 Graph for Calculating Specific Speed nq Schedule for Calculating the Operating Point

6

Handling Viscous Liquids

17

7

Typical Selection Examples

Head Losses H v in Plastic Pipes Head Losses H v for Viscous Liquids

in Straight Pipes 4.4

Head Losses H v in Valves and Fittings

5

Changing the Pump Performance

9 11 11 13

and fH,z for Viscous Liquids

or Pump Size for Viscous Liquids

Selecting the Pump Size Calculating the Power Consumption Pump Power Input Calculating the Drive Rating Calculating the NPSH" Suction Lift from Open/Closed Tank Positive Suction Operation from Open/Closed Tank 7.3.3 Positive Suction Operation from Closed Tank

7.1 7.2 7.2.1 7.2.2 7.3 7.3.1 7.3.2

at Vapour Pressure

7.4 7.5 7.6 7.6.1 7.6.2

Changing the Speed Trimming the Impeller Handling Viscous Liquids

Calculating the Operating Point Establishing the Pump Size

22

33 34 35 37 38 39 40 41 42 43 44

18 18 19 19 19 19 19 20 21 21 21 21 21 . 22

3

fa f~

g

H

HA Hgeo

Ho

Hs geo Hz geo

H, H v.s ~H

K k

L n NPSH req

NPSH"

nq P p Pb

Po

p,

~Q

Q Q min

R Re U

v y Z

Conversion factor for flow rate

Conversion factor for efficiency m/s:2 Gravitational constant = 9.81 m/s 2 m Head m System head m Static head m Shut-off head m Static suction lift m Static positive suction head Head loss m Head loss - suction side m Differential head m 1 Coefficient mm Absolute roughness Length of pipe m llmin Speed NPSH required m m

NPSH available 1/min

Specific speed kW

Pump power input bar (N/m') Pressure bar (N/m') Barometric pressure bar (N/m 2 ) Vapour pressure of liquid bar (N/m 2) Pressure loss lis (m 3 /h) Differential capacity lis (m 3 /h)

CapacitylFlow rate lis (m 3 /h)

Minimum flow rate mm Radius 1 Reynolds number m Circumference mls Flow velocity mm Stroke llh Switching frequency Height differential between pump m suction and discharge nozzles Loss coefficient

I'

v

p

1 m 2/s kg/m 3 (kg/dm 3 ) 1 o

The head H of a pump is the useful mechanical energy trans­ mitted by the pump to the medium handled, related to the weight of the medium, expressed in m. It is independent of the density p of the medium handled, i.e. a centrifugal pump will generate the same head H for all fluids irrespective of the density p. The density p determines the pressure within the pump p=p·g·H and influences the pump power input P.

2.3 System Head The total head of the system HA is made up of the following (see Figs. 1 and 2): • H"a. Static head = height difference between the suction and discharge fluid levels. If the discharge pipe emerges above the liquid level, then Hgeo is referred to the centreline of the outflow section.

• Pa - Po, the pressure head difference between the suction p.g

and discharge fluid levels in closed tanks.

• ~H" the sum of all pressure head losses (pipe friction, friction in valves, fittings etc. in suction and discharge pipes). 2

The system head HA is thus: HA = Hoe,

Temperature factor Opening angle

for open tanks

e G geo K

s opt R sch

W Z

1,2,3 4

at outiet cross section of the systemlbranching off at operating point at discharge nozzle of pumplflowing through at inlet cross section of plant/branching off for cast iron geodetic tor plastic suction side, at suction nozzle of pump at best efficiency point radial for sulphuric acid for water for viscous liquids consecutive numbers, items

v

2-

v

2

In practice the difference between the velocity heads can be ignored, leaving for closed tan ks

Indices

B d

Pa - Pe

a a + -p.g + ~ + ~H,.

Pump efficiency Pipe friction coefficient Correction coefficient Kinematic viscosity Density

HA = Hgao

HA

a

2

• Va ;gV e , the difference in velocity heads in the tanks.

=

H geo

+p, -p, + ~H p.g

~"

+ ~Hv·

2.4 Speed With three-phase motor drives (asynchronous squirrel cage motor) the approximate pump speeds are as follows: No, of poles Frequency Aororenca speeds In curve documentallon In l/mln

al 50 Hl at 60 Hl

2900 3500

11450 1750

I1160 960

1725 875

1580 I 700

1"0 5aO

1415 500

In practice, however, motors usually run at slightly higher speeds which - upon consent of the customer - are taken into account by the pump manufacturer at the design stage (see section 7.4). Different speeds are possible using a speed adjustment device, gearbox or belt drive.

Hgeo

~It-----------,s. ======;-)---4

d

Hsgeo

•

Fig. 1 Pumping system with suction lift

Hgeo

P.

Fig. 2 Pumping system with positive sucllon

5

the operating point near Qopt (b.e.p.). For pumps handling viscous liquids see sections 6 and 7.6.2

The characteristic curves apply to the density p and kinematic viscosity v of water, unless stated otherwise.

2.6 Calculating the Power Consumption 2.6.1 Pump Power Input (see exampie in 7.2.1) The pump power input P of a centrifugal pump is the mechan­ ical energy at the pump coupling or pump shaft absorbed from the drive. It is determined using the following equation: p·g·Q·H. P ~ 1000. ~ tn kW with p in kg/dm 3 9 in m/s2 Q in lis H in m ~ between 0 and 1

== ,

~

~

~

~ ~

~ ~

I"

= = E

" =

\!S

100 q GPr 1411 180 180 eoIG13l14O

"'

"

57 ,

"" , ,

, , "

J"

•

• , •

=

~

The pump power input P in kW can also be directly read with sufficient accuracy off the characteristic curves (see 2.7) where the depsity p = 1000 kg/m'. The pump power input P must be cdnverted (see 7.2.1) for other densities p.

•.=

~

"

~

=

"'3,M:J:l

~

'"

u

="

=

"§; •,

-= " ,.= ~

Since it is possible that the system volume flow, and thus the operating point, will fluctuate, which could mean an increase in the pump power input P, it is standard practice to use the following safety margins when determining the motor size, unless the customer specifies otherwise: up to 7.5 kW approx. 20%

from 7.5 to 40 kWapprox. 15%

from 40 kW approx. 10%.

I""

I;:

~

2.6.2 Calculating the Drive Rating (see example under 7.2.2)

I;:

/9'W1112U

~

with p in kg/dm 3 Q in m3 /h H in m 367 conversion factor (constant)

"" ""

"

&2,5_

=

p·Q·H. P = 367. ~ In kW

Z20 180 ~

"

or another equation which is still used:

200

,.=

.

-

9101112131. In a plsstic pipe at 10°C waler temperalura; ploUed in lunctlon oillowvalocily v

1.1

Q

.~

: ~

60

Temperature t Fig. 15: Temperature factor lor calculallon 01 head losses in plastic pipes al water lemperatures between 0 arld 60 °C

Increments of 20 to 30 Ofo should be added for sewage or un­ treated water.

Thus, HYFI = 0.08 . 0.14 "'- = 0.53 m/100 m. 0.021·100m One qUite common viscous fluid is celluiose (pulp pumping), the viscosity of which depends on the fiow velocity. since the material in question is "non-NEwrONian"! Figures 17 a through 17 f offer reference values for the head losses H, per 100 m iength of straight steel pipe run plotted against capacity (H, = flO); nominal bore: 100, 150,200, 250, 300 and 350 mm) for conveying unbleached sulfite cellulose at 15 "C, 26 cSR

a

11

m10 I

300 f----- 1- 200

Pulp density in % bone dry

ON 100

7,

""

100

.0

r-- 50 40 :i 30

-

,5 3,0 A

--- ---

~ 20 .Q

~ 10 1----. I

-- ­

5

I--

5

3

Fig. 17a

300 200 m

100m

100

--

-

A

-_ ...

--

'" 30 ;:::;

j!! 10

I

~

I

-----

I-

~

--

2 1 20 30

Pulp density

in % bone dry

-._.

4

3

2 10

20 30

50

Fig. 17 b

100 200 m Rate of flow Q

200 --!!l.­ 100m

ON 200 --

-- f - - -­

~

500

_.'

_l-g 10 V -:::::

I-

----

.

A

~

I

1 2.S

Fig. 17 c

12

2.5- f ­

1.5_ f ­ A

- --­

"

.

100 200 m3 /h 5,00 Rate of flow Q

50

1000

350

2000

Pulp density in % bone dry

t

",",,7.~=

-:.6.~_

;,....5.0_ _5.5_ 5,0­ 4.5_ _4.0

__ 3.5

3.?-== A ~2,5-

2.?-==

5 4

3

1.5­ A

I­

2H---:b4-1"fH+-t±>-""""'I-H--+-:bH-Ft++++-t--I

1.5

1­ 20 30

,,! 100

f­

2.0_ f ­

"0

I

2 50

1= 1=

3.0 A A

'" 10 ~

3

30

l- I-

I

A

20

I­

I-­

,20

1.0 5.5 5.0 5.s 5.0 4.5 4.0 3.5

2.0

~

1 10

-

V

50 40 30

- -

I

--­

ON

3.0 A

~

100

Pulp d enSi~ in%b one ry

-

.Q

6.~_ 5.~_

5.04.5 4.0- f 3,5_ f -

1000

100

50 40 :i 30 ~ 20

6.~=

,

!

3 /h

in % bone dry

7,O----=--~

Fig. 17e

1.5

5

1000

A.Pulp density

f­

3

y

H

ON 300 f--

5 4

2.5

~ A A

I-

50 100 200 m3 /h 500 Rate of flow Q

,20

3.0

~

-g

100

7.0 5.5 50 5.5 5.0 4.5 4.0 3.5

-- -

50

'"

50

"0

-_ ... -

30

50 40 30

~ 10

:i 40

.Q 20

10 20 m3 /h Rate of flow Q

ON 150

--

20

m 100m

,

3 2

!

100

,

1

­

,.-

Fig.17d

f-----

2

A

\5

4

"

1 10

" "

--- --

~

r--

"0

2 1.5

4 3 2

5,5 ,0

100m

A

5

5

--!!l.­

--

200 m3 /h 500

Rate of flow Q

1000

Fig, 171

~

V 50

100

,

3

200 m /h 500

1000

2000

Rate of flow Q

Figs. 17a-f: sllow a plot oltha head losses Hv lor conveying sulphite cellulose a/various pulp densities at a temperalure 01 150 QC and a grinding grade 0126 QSR (piPe dlameter6 DN 100 10 DN 350) A-A= maximum velocity (2,44 or 3.05 m/s) in the discharge pipe loreconomical operation.

For an 18 % kaolin content, the head loss value will decrease by 12 %, and for a 26.5 % kaolin content, it will decrease by 16 %.

Tables 2 to 4 and Figs. 18 to 24 give details of the indivi­ dual loss coefficients ( and head losses Hv in valves and fitt­ ings for operation with water.

4.4 Head Losses Hy in Valves and Fittings 10

2

5

'1

II

-/- -I 1/

/ / / IV

/

IV

L -I

.;

IV

1/

) Y' ~

/ /

/

1/

/

I

7"-; 1/

0.2

~

\

"- r-­

.3

~

-

~

o o

0.4

~

f

_._.~

'.~

0.5

-

~tJ

-f-------_a Cl

with guide vane cascade

-,.~

---

t

Outside radiused

~ 0.4

,­

-'

-aoORK _

()

vv V

/

/ 1/ /1 0.1

~

'" 0.8 '13 iE

"

/

V IV

/ 1/ Vv

7I

I

\

c

v'~JG~. I/~

. _.

0.2 0.03 0.05

I

"-'

-"J~~

V V V V 1/ / / 1/ / /

/ /

..,,,

/

V IV vv Vv I I

/IV

1.2

/

' ....'?j

1/ II /

-/ Iv

/­ / 1

....

/

1-- ,Ltt

~

0.3

IV

V IV ,y,'t IV II 7,~ IV IV II V

I;

0.4

I

/7

V

~~~~I -j/

V

0.5

'/

/

~~., II/ V / 1/ f/~~" ~.,.. / / / O:::>'rl\ / 1/

/

4

,

,,"'/

I

~~

Inside radiused

0.8 Elbow radius RK Duct width aD

g.

•

1.2

-

.'.

,••

Fig. 20: Influence of rounding orr of concave and convex side on the 1055 coelflclent 01 elbows with quadrallc cr05S section

1.0 m 2.0 3.0

Head loss H, 10'

\\ .

5

,

Knee piece

-l45'

50'

Surface

~ .

I

(

90'

2

smoothl

rough

smoothl

,rOUgh

smoothl rough

0,25

0.35

0.50

0.70

1.15

1,30

~

JL~ r= ;

with sharp edges

rounded wllh straight bollom (= 0.7

spherical with Inward-rounded neck I; =O.g

Fig. 19: illustration of IllIings wllh relaled 105S coeffiCients I;

,-

60 0 74 900

\\-'r-- I­

JI~

CCI?

spherical

(=2.5104.9

1\-

--

I­

'\, [\

"­ ~

, " , I'

',- l- I-

0.5 Relative opening angle ('1'0- '1')/'1'0

9

i_

min

max

axial

min

max

non-return valves,

straight-seat

11

9

max min max max

8

7

min

max

6

5

slanted-seat valves

angle valves

valves, cast

valves, forged

4

swing-type valves PN 5;;: 2.5

PN '" 40 min max min max

3

2

1

Design 3 Loss coefficient (for DN =

min max

varves (dE = DN) cocks (dE = DN)

non-return valves,

(J)

"

.!.

.c

0

""'

""'>>

min max

round-body gate

(dE=DN)

min max

flat gate valves

Type of valve/fitting

Table 2: Loss coefficients (of valves and fittings (referred to the velocity of flow in the

1

11

12

5

4

3

2

6

14

13

15

7

17

16

10

9

8

19

18

Designs according to Table 2

The minimum and maximum values listed in Table 2 include figures taken from the most pertinent trade iilerature and apply to fully open valves and fittings under uniform conditions of flow. The losses attributable to flow disturbances in a length of pipe equalling ca. 12 x DN downstream of the valve or fitting are also included in those values (cf. VDIIVDE guideline 2173). Nonetheless, the actual values are subject to wide variance, depending on the conditions of inflow and outflow, the model in question, and the design objectives.

Inlet pipe fittings:

D'1

GOllA t t t +

Inlet edge

sharp , = 0.5 0.25 chamfered,

=

3 0.55 0.20 0.05

!"

,=

for"

=

... 'Of

75° 60° 45° 0.6 0.7 0.8

,=

Discharge pieces:

1 downstream of an adequate length of straight pipe with an approximately uniform velocity distribution in the outlet cross-section. , = 2 in the case of very unequal velocity distribution, e.g. immediately downstream of an elbow, a valve etc.

Table 3: Loss coefficients for fittings Elbows: Cast elbows goo, R = D + 100 mm, all nominal size, = 0.5 Pipe bends goo, R = 2 to 4 x D Nominal size DN

,

50 = 0.26

100 0.23

If the deflection angle only amounts to the above, values should be multiplied by

Loss coefficients of flow meters:

200 0.21

300 0.19

0.85 0.7

500 0.18

0.45 0.3

Knee pieces:

,

Short venturi tube a = 30 °

Standard orifice plate

ffit[[J

fJJDJ OI~O:l'l

, is related to the velocity v at diameter D.

Diameter

ratio diD

0.30 0.40 0.50 0.60 0.70 0.80

Combinations of elbows and pipe bends:

Aperture

ratio m = (diD)'

o.Og 0.16 0.25 0.36 0.49 0.64

The, value of the single goo elbow should not be doubled, but only be multiplied by the factors indicated to obtain the pressure loss of the combination elbows illustrated:

6 Short venturi tube , = 21 , = 300 85 Standard orifice plate

goo

Deflection angle ~

~

1.4

1.3

60° 0.7

45° 30° 0.35 0.2

15° 0.1

2 30

0.7 12

0.3 4.5

0.2

2

=

10

Water meters (volumetric meters) , In the case of domestic water meters, a max. pressure drop

of 1 bar is prescribed for the rated load, and in practice the

actual pressure loss is seldom below this figure.

1.6

1.8

Branch pieces: (Branch of equal bore)

a,

Expansion joints:

a

Bellows expansion joint with I without guide pipe , = Smooth bore pipe harp bend , Creased pipe harp bend , = Corrugated pipe harp bend , =

=

0.3/0.2 0.6 to 0.8 1.3 to 1.6 3.2 to 4

'd

The resistance coefficients " for the diverted flow or respectively for the main flow ad = a - a, relate to the velo­

city of the total flow in the nozzle.

On the basis of that definition, " andlor may take on

negative values, in which case they are indicative of pres­

sure loss. Not to be confused with reversible pressure

changes according to BERNOULLI's equation (cf. annota­

tion to Table 4).

'd

15

a, Q

= = =

(d ~50 Qd

~Qa

(, (d

0.17 0.68 -0.06

0.19 0.50 -0.04

0.09

-0.17

0.38 0.07

0.35 0.20

(= 16·­

0.48

k;

where d reference diameter (nominal diameter) of the valve or

fitting in em. 5

Table 4: Pressure change coefficients in transition piece for arrangements illustrated in Fig. 14 A coefficient f: in accordance with the values in the table below applies to each ot the illustrated shapes of transition pieces/ reducers. If the pressure rises across the transition piece in the direction of flow (divergent section), E is positive, and if the pressure drops (reducer), E is negative. Coefficients: Expansion

rn v£[t¢

diD = 0.5

(= (= 8° II for a = 15° (= = 20° (= III (= IV for 20° < a < 40° ( =

r= ct

'0100:24'

III

II

Form

5.1 Changing the Speed The same centrifugal pump has different characteristic curves for different speeds; these curves are interconnected by the similarity law. 11 the values for 0 1, H1 and P1 are known at speed nj, then the new values for n2 will be as follows:

IReduction

~ ~ Form I

Changing the Pump Performance

0.56 0.07 0.15 0.23 4.80 0.21

IV

0.6

0.7

0.8

0.9

0.41 0.05 0.11 0.17 2.01 0.10

0.26 0.03 0.07 0.11 0.88 0.05

0.13 0.02 0.03 0.05 0.34 0.02

0.04 0.01 0.01 0.02 0.11 0.01

A change in the speed also causes the operating point to shift (see 2.9). Fig. 22 plots three OH curves for the speeds n1, n2 and n3, each curve is intersected by the system curve HA at points B" B, and 8 3 respectively. The operating point will move along the system characteristic HA from 8 1 to 8 3 when the speed is changed as indicated.

B,

Note:

In the case of branch pieces as per Table 3 and transition

r

~ r

pieces as per Table 4, differentiation is made between irrevers­

ible pressure loss (= pressure reduction)

,/ /Hllnes

B Operating point

n Speed

P 'v'

P'=('T on the one hand and reversible pressure changes involving frictionless flow as per BERNOULLI's equation (fluid dynamics)

p, - p, = ~ (vl - v;) on the other. In the case of accelerated flow, e.g. through a pipe constriction, P2 - Pl negative. Conversely, it is positive in pipe expansions. By contrast, the pressure losses ascertained

by way of the loss coefficients ( are always negative, if the overall pressure change is calculated as the arithmetic sum of P.. and P2- Pl'

'-------------------;;;u"o~ Capacity Q Fig.22 Eltec\ of change in speed

5.2 Trimming the Impellers Permanently reducing the output of a centrifugal pump oper­ ating at constant speed (see Fig. 23) entails reducing the impeller diameter D. The characteristic curve booklets contain the pump curves of selected impeller diameters in mm. When trimming radial flow impellers (see 8.4) (trimming is not a geometrically similar reduction of an impeller since the outlet width normally remains constant), the relationship between 0, H and impeller diameter Dis:

In the case of water transport through valves and fittings, the loss coefficients ( is occasionally neglected in favour of the so-called k",-value:

- (0k; )' '1000 p

P,-

16

D2

~ 1· ~,~ ~D ~ D 1 • I~' -. 0, H,

(see 8.4), • specific speeds nq of 6 to 45 1/min (see 7.6.1 and 9.12), • kinematic viscosities V z of 1 to 4000 . 10-6 m2/s (kinematic viscosities below 22 . 10-6 m2 /s are normally disregarded).

H2

e--------------~

82 ..

I

~

I

Capacity Q Fig. 23 Influence of Impeller diameter

1,.~ft~~~i~i~I~~;

",.

10

6 Handling Viscous Liquids As the viscosity v of the medium handled increases (at con­ stant speed) the capacity Q, head H and efficiency ~ fall; at the same time the pump power input P rises. The best efficiency point shifts to smaller flow rates. The operating point Bw drops to Bz (see Fig. 24).

,~

1::f-H--f+I+++i-= :: 6;,,,~f,l:rl:l:rl:l:

r.~o>

I

~

I

Capacity Q Fig. 24 Change In operating point when handling viscous liquids (Z) end waler (W)

The standard operating point for water Bw with Q w• Hw and ~w (W = water) is converted to the viscous liquid operating point Bz with Qz, Hz and ~z (Z = viscous liqUid) using the conversion factors for viscous liquids fa, f H and fl] (see Figs. 25a and 25b).

" ... " ","

~.,J'--e'L'l'=~'"---c-"'~""­

Capacity QZ,Betr. QW,oplln

m'

I

h;;

Fig. 25a Determining the conversion factors fa,w, [H Wand ['l,W lor handling viscous liquids (enlarged version sae 9.1 0), II the operating pornt lor handling watar Is given

17

Density Temperature Kinematic viscosity

p, = 1.5 kg/dm 3

ts = 20°C

Vs = 3.8 ' 10-6 m 2/s (can be

disregarded. see 6) (p, and v, taken from standard reference tables)

The pump selected for this particular liquid is a CPK series

standardized chemical pump.

Technical data and characteristic curves for the CPK are given

in the characteristic curve booklet and selection booklet (Figs.

26 and 27 are extracts) .

• Selecting the size of the pump: Using the CPK/HPK characteristic curve booklet for 50 Hz the selection charts give the following pump selections for

the specified operating data:

1/min and

1/min.

CPK 65-250 at n = 2900 CPK 150-250 at n = 1450

The CPK 65-250 is selected for reasons of economy.

Fig. 25b Determining the conversion faclors fa,z and fH,Z lor handling viscous liquids {enlarged version see g,11}, If the operating pO,lnt lor handling viscous liquids IS given

10

U.S.gpm

20

30

10

200 -

40

I

Imp.g.p,~.

I

I

30

20

50 I 40 50

-­

,

200 300 400 500 I I, I , 200 300 400 500

'00 I '00

r-­ 40~315

100

I

1/ 40-250

32-250

-

m

L

-~

-.I.

i'.

50

3Z -ZOO

- --- - - -- -

1/

50-250

50-200

/ ..

- -- --- - - - - -

_.. ­

--- -

t'--­

------ ------

30

--

32-160

20

,......

"­

~5

- - ----------

2

c'

/ 2

4,

Fig. 26 CPK/HPK, selection chart n = 2900 1/mln

3

--

-

/

'0

4p 5.0

-----

"'­

/

l

60-160

I

­

125-315

I

~-

H

It

200

1/

/

A

1/

100

/

'v I~ "- f --

20

400 300

"125-250 /

/

100-200

-

5

100-250

80-200

I··

4

1

80-250

----

t--r--(

1/

/

/

/

rv

i'-- -~ / K.

K --- N

1/

--- ["'; -

1---

'J /

65-160

500

100-:~'5

11-_____..

50-160

"- J

'--

)._65-200

r--

r­

--­

1/

Q[/s

1

"

/ '-

T--­

I"< t',

j

65-250

-.......,

-

,......

_

t-- r­

10

/

-

-----

;--

32-125° C~

---- --- - -

/"0-160

-

---

'--

~-

-r--:

80-315

"'N 1/

f::::: k

i'-­

7

65-315

f

40-200

40

18

1/

50-315

-r-.

-

_ ..

I

I

!

1000

-

I"'"

---- r--.

i'-

I

!

-

+-­

--

H

I

--­

--- -­

80

2000

1000

2

30

40

50 ­

40

f--­

50

'00

14

• Pin value must be Checked (see selection booklet, section Technical Data).

Q

in lis

H

in m

P

in kW

or an alternative frequently used in practice:

If the operating point temporarily changes to higher flow rate, the motor rating must be increased accordingly, if necessary up to the maximum possible pump power consumption.

p,·Q·H 1.5·90·80 P = 367 .~ = 367.0.68 1) = 43.3 kW

A recheck of the Pin value then becomes important as a criterion for the bearing bracket.

with

p,

in kg/dm 3 in m3 /h in m in kW

Q

H

P

The pump power input P can also be established with sufficient

accuracy from Fig. 27.

P is interpolated as = 29 kW for water, the value for sulphuric

acid is:

P = 29 .f'.L-= 29· Pwater

~= 43.5 kW, 1

'} Efllciency 11 (from Fig. 27) interpolated

..,

""'"

....

U~,Gp~

1M GPM

.. ..

..,:oqo

~_.L_L.L 1~ L L

.

.

'"

..

7.3 Catculating the NPSH.. (see 3,2)

To achieve cavitation-free operation of the pump the limit of

maximum possible suction lift He gao, max. or the minimum required suction head Hz gao, min. must be adhered to.

!;:

~+

0

• ,

.. "" " .. .. .. " s

,

, '"

'"

'"

...

-­

.. '" ... ..

.,

~

'"

!;:

~

" '"

"

~

...

!l!

~

L

.: F

;

50 ;;:

L

-r~

. "t··

.. "'" .. ., ..., ..

..

~-,-3llO

.. '" .. ..

., II!

..

"

'"

" , 0

"

.

", '" '"

Fig. 27 Characlarlallc curvas CPK/HPK 65_250

..

"

.,"

;;:

7.3.1 Suction Lift from Open/Closed Tank Here the pump is above the liquid level (see Fig. 10).

Selected pump is a CPK 65-250, technical data see 7,1.

Calculation of Hs gao, max. is based on following system and pump data: = 1500 kg/m 3

p =1 bar=1·10'N/m'

Pb = 0,0038 bar = 0.0038'10' N/m'

Po (from reference table)

(60% sulphuric acid at 20 "C)

= 1.5 m (estimated from Fig. 13 for 10m suction

Hv.s pipe ON 100, inci. fitlings and valves) v, can be disregarded because negligible NPSH"q= 3.3 m (interpolated from Fig. 27 inci. 0.5 m safety margin) 19

~

,

~

p ~O

J

Po?"

'I

I

i

~_~-_C1==~_-",_=

t--

He geo, max =

H"",, m" = ~

Po,t,s,v,

/

Pe+Pb-PO Pe.g - Hv,s - NPSH r8Q

0+1·10'-0.0038·10' 1500.9.81 - 1.5 - 3.3

.

(ace. to 3.2 with NPSH req = NPSH av)

H,goo,m,,=

6.77 -1.5 - 3.3

1.5·10'-0.0038·10' 1500.9.81 -1.5-3.3

= 10.17 - 1.5 - 3.3 =5.37 m.

= 1.97 m.

With He geo, max = 5.37 m, NPSH av = NPSH raq = 3.3 m; therefore NPSHav ~ NPSH req requirements is satisfied.

With He geo, max = 1.97 m. NPSH sv = NPSH req = 3.3 m; therefore NPSH av ~ NPSH req requirement is satisfied.

7.3.2 Positive Suction Operation from Open/Closed Tank Here the pump is below the liquid level (see Fig. 11). Selected pump is a CPK 65-250, technical data see 7.1 to 7,3.1,

::o,ep::::e:..on-.::ta"n"k"----:c-;- Given: p, = 0 bar

~

, I

~

p.~o

I

I.::C"loo::s:::;eood-.::ta"n"k'-----,c-::-:---,-::--:-:c::-:-:-:-:------­ Given: p, + Pb = 1.5 bar = 1.5 . 10' N/m' I P.+Pb

i

i

j

~---=et==: ---==,

t-v.,po ,t~

H'Qeo

Datum lavel

Hzgeo, min = NPSH req

H, "0, ml' = 3.3 + 1.5 -

0+1·10'-0.0038·10' 1500.9.81

+ 3.3 - 6.77 = -1.97 m.

= 1.5

+ HV,8

.....

e--.-JtoII

-J

~+~-~ -

Ps'g

H, "0, m" = 3.3 + 1.5 -

1.5 ·10' - 0.0038·10' 1500.9.81

=3.3 + 1.5 -10.17 = -5.37 m. Negative heads -H zgeo ere suction lift heads +H aQeo of the same value. The minus sign in the result tells us that the centrifugal pump, with an open or closed tank. could draw roughly the absolute amounts as in example 7.3.1 where the requirement NPSH av ~ NPSH req is just about satisfied. This requirement would be more than satisfied in example 7.3.2 with a positive static suction head (as shown in the diagram).

20

I iIJl3::3­

0,

+ 1.5 - 0 =4.8 m.

= 3.3

~ 0 , . ~ = 240 . V;;.56 = 237 mm.

Turning the impeller down from 240 mm (0 , ) to 237 mm (0,) restores the original duly given in 7.4. It is, however, standard practice not to make such minor changes (less than 5 mm) to the impeller diameter.

From 4.8 m upwards (Hzgeo,mln)the condition NPSHav~NPSHreq is fulfilled.

7.6

7.4 Changing the Speed (see 5.1) The CPK 65-250 selected in 7.1 but with the following per­

Handling Viscous Liquids (see 6) Schedule on page 44.

formance data (present duty: index 1, new duly: index 2)

0, H,

25 lis (= 90 m'/h) 70 m . = 2900 1/min at n, and 0 , = 240 mm (impeller diameter) is driven by a 55 kW three-phase motor with a nominal speed (n,) of 2965 1/min. The higher speed shifts the operating point, without considering the system characteristic HA , as

7.6.1 Calculation the Operating Point The prodUct is a mineral oil with a kinematic viscosity Vz of 500 . 10- 6 m'ls and density pz = 0.897 kg/dm'.

We know the characteristic curve and operating data of a pump handling water, where:

0, = 2900 . 25 = 25.56 lis (= 92.02 m'/h)

Ow = 34 lis (= 122.4 m'/h) Hw = 18 m n ~ 1450 1/min

2965)') H, = ( 2900 . 70 = 73.2 m.

To obtain the new data for mineral oil, the pump data at the b.e.p. must also be calculated and the following additiona information must be known:

If this increase is not acceptable, the original duty can be restored by e.g. reducing the impeller diameter (see 7.5).

Capacity

Q Woot

Head Efficiency

Hw oot llw oot

Speed Kinematic viscosity

Vz

Density Gravitational constant

pz g

follows to:

2965

7.5 Trimming the Impeller (see 5.2) The unacceptably high pump output (see 7.4) caused by the higher motor speed is rectified as follows by trimming the

impeller (present duty: index 1, new duty: index 2).

n

31 1) lis 20 1) m 0.78 1) ­ 1/min 1450 500.10-6 m2 /s kgldm' 0.897 9.81 m/s 2

1) Irom Individual characteristic curve (aee Fig. 27)

4 points on the new characteristic curve can be established using the calculation chart below: nQ,W from graph in 9.12

27

1/min

~

0.78 0.83

-

0.49

-

M

from Fig. 258 or sect. 9.10,

page 41

ffl,W

0/00

t

from charact. curve booklet ~ for 4 points '1w on curve

"""-

Qz = Ow' fQ,w Hz

=

TJz = Tlw' f.."w

Pz=pz·g·Hz·Qz ~z·1000

2) if Hz

0 0 25

0.8 24.8 21.6

0

-

1.0 31

1.2 37.2

0.74

20 0.78

18.2 0.73

-

0

19.3

24.2

29

lis

=~

~

25'

') 18.5

m

0.36

16.6 0.38

15.1

0

0.36

-

8.7

9.3

10.7

kW

IX

> Hw, use Hz =

Hw

Hw· fHW·1.03 = Hw·fHW

~

lis m

Hw·fftY'

, H

HwBot •

•

These velues meen 4 pointe on OH z end Q"1z line plus :3 points on the QP z line ere establishsd, Plotted over Q (see Fig. 28)

Hz Btlr.

,. Q z Stir, Q w BII•. 0'0""

Q

Calculation in graphic form

2

Use the following calculation table to convert to operating data with water and thereby find the appropriate pump size. n selected n,.w 3) from graph in 9.12

1450 27

1/min 1/min

~ from Fig. 25b or

0.8 0.86

-

38.8

lis

23.3

m

fH,l

section 9.11, page 42

Q

_ Q z Selr

W,Belr -

H

where

H

H Wlhtr.

­

az

_ Hz 1

W,Belr -

3)

f

,

Selr

HZ

QZ,Betr = Qopi )

Hz, Betr

approx.

= HOpl

Calculation in graphic form

The definitive operating data when handling water are thus:

25,,_ _

Qw.•", = QW = 38.8 lis (= 139.7 m3 /h)

H

m

HW,Belr

20

Based on these data a suitable pump is seiected from the sales documents selection chart. Using the curve thus estab­ lished, follow section 7.6.1 to establish 4 points on the new characteristic curve.

Hw 15

H,

These 4 points can now be used to establish the curve to be expected for handling mineral oil, see Fig. 28.

1)

I "0

'1.

~ .J\' d.1Il~

>bo

I

~"~

~~ ~ ,

underneath

L

Alternative installation a b c

----- --with parallei axis above pump with belt drive and outboard bearing or jackshaft

underneath

or horizonlallnslallaUon

simpie speed variation

.

I

I

wet installation a) permanent b) portable

.if

I

FIQ.41 Examples 01 vertical mounting

27

Motor rating above 30

max. 10/h

kW

Start-up frequency is calculated using:

Z

3600 . Q w (Qm - Q w ) VN • Q m

,

-'

- , ... \

,~wrong

L

Inle( pipe

f-

'

"

..­

where Z

no. of starts per hour Q zu inlet flow in I/s Q

e-' Sump

Qe+Qs, m

2

'-

Q s capacity at switch-on pressure in I/s

~

"

Q, capacity at switch-off pressure in lis

VN useful volume of pump sump including possible flowback volume in I

pas. deflector

Fig. 43 Piping arrangement to prevent air entrainment

The maximum start-up frequency occurs when am = 2 x Ow. Le. when the capacity am is twice the incoming flow Q zu . The max. start-up frequency is therefore:

With dirty liquids, soiids must be prevented from being de­ posited and collecting in dead zones and on the floor. 450 walls, or better still 60 0 walls, help prevent this (see Fig. 42).

The medium handled must cover the suction pipe inlet to a suitable depth, otherwise rotation of the liquid could cause air-entraining vortices (hollow vortices) to form; starting with a funnel-shaped depression at the liquid surface, a tube­ shaped air cavity forms instantaneously, extending from the surface to the suction pipe. By ensuring that the medium handled always has a suitable level (see Figs. 44 and 45) or by taking measures to prevent vortices (see Figs. 46 to 48) this can be prevented. which is the more important, the higher the flow rate is.

~~),;"'.:~

-

0

!.---_.

----.J /

-Suction pipe to pump

Fig. 44 Arrangement of pipes in the suction tank (eump) 10 prevent vortices

-

Suction pipe

The minimum liquid cover 8 mln in m must be the velocity head plus a 0.1 m safety margin for non-uniform velocity distribution. The maximum flow velocity Vii! in the suction pipe or inlet pipe should not exceed 3 m/s; we recommend 1 to 2 m/s.

v' S

8 mIn = 2 9 +0.1

Flg.42 Inclined sump walls 10 prevent solids from being deposited and collecting

28

with v, flow velocity in mls

8 mIn minimum liquid cover in m.

~ 8°,6 0,5

0,4

-

This is preferred arrangement, -.>..~

0,3

,

--Jr--._. -1-7 f----/---I---I--I---Ic-+++-+-+-H-I----II----+--+ /' ~

0,2

rrti LJ~

r-+­

~

+-+­

..j..j~

~

+-1­

Curves are for ---/; ~ this suction pipe ~W~ arrangement -I-1-1­

0.1

5

100 Fig. 45 Liquid cover S

I

8S a function of the piping bore DlII and capacity

6

7 8 9 1000 2 Capacity Q -----­

Q

Fig. 45 shows the interdependence between liquid cover S, piping bore ON and capacity Q. The values obtained give sufficient protection against vortices. The graph can be used for the suelion pipe layout illustrated.

Figs. 46 and 47 show typical arrangements used to prevent air-entraining inlet vortices where the minimum liquid cover is either not available or cannot be ensured. Fig. 48 shows a speciai arrangement which Is frequently used - a round tank with a tangential inlet pipe which causes the contents to rotate.

r /"

(

Suction

'-.I......,.----,P'P' '--

D

-=....J

/

Fig. 46 Raft \0 prevent lormElUon 01 vorHeBS 10 pump

_

Bema Baffle Radial baffle

I

8affle

\ Axial b&ffle

Fig. 47 Use 0' sWlrl-prevenling bellies

) I

Suction pipe

T,"',""@ o to pump

II

I

U

Inlet

___

Flg.46 Use 01 bafflee in the lank 10 ensure disturbance-free flow 10 pump

29

• • • • •

Muff couplings, Serrated couplings, Split couplings (DIN 115), Face plate couplings (DIN 758, DIN 759), Flange couplings (DIN 760).

Flexible couplings to DIN 740 are elastic, slip-free connecting elenlOnts between drive and driven machine which accom­ modate ax-lal, radial and angular misalignment (Fig. 49) and damp shock loads. The flexibility is usualiy achieved by the deformation of damping and rubber-elastic spring elements whose life is governed to a large extent by the degree of misalignment. Fig. 50 shows the most common types of flexible couplings. Fig. 51 shows a spacer coupling between a pump and drive; its function is to permit removal olthe pump rotating assembly without disturbing the pump casing or drive (back-puli out design).

FIQ. 50 Typical couplings

---1

9JfP .

Fig. 49 Misalignment

30

-I

·,! ttl!} '

. l ""'·.11

Flg.51 Pump with spacer coupling

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

273.15 274.15 275.15 276.15 277.15 278.15 279.15 280.15 281.15 282.15 283.15 284.15 285.15 286.15 287.15 288.15 289.15 290.15 291.15 292.15 293.15 294.15 295.15 296.15 297.15 298.15 299.15 300.15 301.15 302.15 303.15 304.15 305.15 306.15 307.15 308.15 309.15 310.15 311.15 312.15 313.15 314.15 315.15 316.15 317.15 318.15 319.15 320.15 321.15 322.15 323.15 324.15 325.15 326.15 327.15 328.15 329.15 330.15 ij1.15 59 332.15 60 333.15

0.00611 0.00657 0.00706 0.00758 0.00813 0.00872 0.00935 0.01001 0.01072 0.01147 0.01227 0.01312 0.01401 0.01497 0.01597 0.01704 0.01817 0.01936 0.02062 0.02196 0.02337 0.02485 0.02642 0.02808 0.02982 0.03166 0.03360 0.03564 0.03778 0.04004 0.04241 0.04491 0.04753 0.05029 0.05318 0.05622 0.05940 0.06274 0.06624 0.06991 0.07375 0.07777 0.08198 0.08639 0.09100 0.09582 0.10086 0.10612 0.11162 0.11736 0.12335 0.12961 0.13613 0.14293 0.15002 0.15741 0.16511 0.17313 0.18147 0.19016 0.19920

0.9998 0.9999 0.9999 0.9999 1.0000 1.0000 1.0000 0.9999 0.9999 0.9998 0.9997 0.9997 0.9996 0.9994 0.9993 0.9992 0.9990 0.9988 0.9987 0.9985 0.9983 0.9981 0.9978 0.9976 0.9974 0.9971 0.9968 0.9966 0.9963 0.9960 0.9957 0.9954 0.9951 0.9947 0.9944 0.9940 0.9937 0.9933 0.9930 0.9927 0.9923 0.9919 0.9915 0.9911 0.9907 0.9902 0.9898 0.9894 0.9889 0.9884 0.9880 0.9876 0.9871 0.9866 0.9862 0.9857 0.9852 0.9846 0.9842 0.9837 0.9832

61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 102 104 106 108 110 112 114 116 118 120

334.15 335.15 336.15 337.15 338.15 339.15 340.15 341.15 342.15 343.15 344.15 345.15 346.15 347.15 348.15 349.15 350.15 351.15 352.15 353.15 354.15 355.15 356.15 357.15 358.15 359.15 360.15 361.15 362.15 363.15 364.15 365.15 366.15 367.15 368.15 369.15 370.15 371.15 372.15 373.15 375.15 377.15 379.15 381.15 383.15 385.15 387.15 389.15 391.15 393.15

0.2086 0.2184 0.2286 0.2391 0.2501 0.2615 0.2733 0.2856 0.2984 0.3116 0.3253 0.3396 0.3543 0.3696 0.3855 0.4019 0.4189 0.4365 0.4547 0.4736 0.4931 0.5133 0.5342 0.5557 0.5780 0.6011 0.6249 0.6495 0.6749 0.7011 0.7281 0.7561 0.7849 0.8146 0.8453 0.8769 0.9094 0.9430 0.9776 1.0133 1.0878 1.1668 1.2504 1.3390 1.4327 1.5316 1.6362 1.7465 1.8628 1.9854

0.9826 0.9821 0.9816 0.9811 0.9805 0.9799 0.9793 0.9788 0.9782 0.9777 0.9770 0.9765 0.9760 0.9753 0.9748 0.9741 0.9735 0.9729 0.9723 0.9716 0.9710 0.9704 0.9697 0.9691 0.9684 0.9678 0.9671 0.9665 0.9658 0.9652 0.9644 0.9638 0.9630 0.9624 0.9616 0.9610 0.9602 0.9596 0.9586 0.9581 0.9567 0.9552 0.9537 0.9522 0.9507 0.9491 0.9476 0.9460 0.9445 0.9429

122 124 126 128 130

395.15 397.15 399.15 401.15 403.15

2.1145 2.2504 2.3933 2.5435 2.7013

0.9412 0.9396 0.9379 0.9362 0.9346

132 134 136

405.15 407.15 409.15

2.8670 3.041 3.223

0.9328 0.9311 0.9294

138 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275 280 285 290 295 300 305 310 315 320 325 330 340 350 360 370 374.15

411.15 413.15 418.15 423.15 428.15 433.15 438.15 433.15 448.15 453.15 458.15 463.15 468.15 473.15 478.15 483.15 488.15 493.15 498.15 503.15 508.15 513.15 518.15 523.15 528.15 533.15 538.15 543.15 548.15 553.15 558.15 563.15 568.15 573.15 578.15 583.15 588.15 593.15 598.15 603.15 613.15 623.15 633.15 643.15 647.30

3.414 3.614 4.155 4.760 5.433 6.181 7.008 7.920 8.924 10.027 11.233 12.551 13.987 15.55 17.243 19.077 21.060 23.198 25.501 27.976 30.632 33.478 36.523 39.776 43.246 46.943 50.877 55.058 59.496 64.202 69.186 74.461 80.037 85.927 92.144 98.700 105.61 112.89 120.56 128.63 146.05 165.35 186.75 210.54 221.2

0.9276 0.9258 0.9214 0.9168 0.9121 0.9073 0.9024 0.8973 0.8921 0.8869 0.8815 0.8760 0.8704 0.8647 0.8588 0.8528 0.8467 0.8403 0.8339 0.8273 0.8205 0.8136 0.8065 0.7992 0.7916 0.7839 0.7759 0.7678 0.7593 0.7505 0.7415 0.7321 0.7223 0.7122 0.7017 0.6906 0.6791 0.6669 0.6541 0.6404 0.6102 0.5743 0.5275 0.4518 0.3154

31

x II

0

'i\

0

~

"i.

~

1;!

'-' w

w

0

~

ro

E w r-

I,j

"'=' x

~

fj u

«

x" z .~ 0

E E

«

'i1,

~ }j

.,. 0

u

>,

I,j

~

'-' w

~

~

x z

0

~

'-' w

~

~

'~"

'-' w

CO

N

~

'-' w

,§

~

d"

S

'iJ,

"i. '-' ~

~

9: x '-'

~

" ro

u

.~ 0

~

"""i. '-'

."

~

~

ro

u

u

«

°C

K

-50

223 228

5.517 6.574

0.00319 0.409 0.545

0.103

0.0127

0.707 0.890

7.776 9.129

0.718 0.932

0.179

0.0255

1.115

-35

233 238

-30 -25

243 248

1.195

0.294

-20 -15

253

-10 - 5

±O 5 10 15 20 25 30 35 40 45 50 55 60 65

273 278 283 288 293

10.65

14.23 16.31 18.59 21.10 23.76 26.86 30.16 33.76

298

47.07

0.0293 0.0516 0.0856 0.115

0.1542 0.196 0.246 0.306 0.377 0.462

1.902 2.363

0.469

2.909 3.549 4.294 0.0159 5157 6.149 0.0306 7.283 8.572 0.0568

0691

1.103

0.0044

1.50

2.201 0.0606

0.389 0.481

0.0245 0.0085

2.069

3.119 0.0996

0.0419 0.0156

2824

4.232 0.1578

0.589 0.716 0.864

3.765

5.609 0.2412

10.03

0.562

11.67 0.1008 13498 15.54 0.1722

0.681 0.817

17.81 20.33

0.2836

4.98

1.55

8.14

2.08

1.047

90 95 100

353 358 363 368 373

2.76

105 110 115

378 383 388

120 125 130 135 140

393 398 403

32

0.150

2.889 3.405

0.247 0.311

343 348

145 150

0.748

1.613 0.0354

0.6979

408 413 418 423

0.0883

1.379 1.672 2.017 2.423

0.050

1.039

04519

70 75 80 85

0.483

1.516

1.118

-

333 338

0.0149

12.34

303

323 328

>,

iii

"

Vapour pressure Po in bar

37.75 42.15

308 313 318

.,. 0

u

0

T

258 263 268

}j

ro a

1

-45 -40

'-'

:f:

'-' ~

~

~

'-'

"

:E

~

ro

~ ~

e

w

~

~

01

E a

'"€