2 Centrifugal Pumps ROTODYNAMIC Two

7/23/2019 2 Centrifugal Pumps ROTODYNAMIC Two

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Prof. Maher Higazy 1

ROTODYNAMICROTODYNAMIC

PUMPS-PUMPS- CONTIUOUSCONTIUOUS

FLOW PUMPSFLOW PUMPS

ByBy

Professor Dr Eng.Professor Dr Eng.Maher !ga"yMaher !ga"y




CENTRIFU#AL PUMPSCENTRIFU#AL PUMPS




CENTRIFU#AL PUMPSCENTRIFU#AL PUMPS

A$$or%!ng &o 'o( %!re$&!on !ns!%e &he !)*e++erA$$or%!ng &o 'o( %!re$&!on !ns!%e &he !)*e++erof &he ro&o%yna)!$ ',!% )a$h!nes &hey areof &he ro&o%yna)!$ ',!% )a$h!nes &hey are$+ass!e% &o &hree &y*es &hey are/$+ass!e% &o &hree &y*es &hey are/

0-A1!a+ 'o( )a$h!nes (here0-A1!a+ 'o( )a$h!nes (here

&he (or2!ng ',!% )o3es !ns-&he (or2!ng ',!% )o3es !ns-!%e &he !)*e++er !n a %!re$&!-!%e &he !)*e++er !n a %!re$&!-

on *ara++e+ &o &he !)*e++er a1!s.on *ara++e+ &o &he !)*e++er a1!s.

Therefore &he ',!% en&ers &heTherefore &he ',!% en&ers &he

!)*e++er a& a *o!n& of $er&a!n!)*e++er a& a *o!n& of $er&a!nra%!,s an% +ea3es !& a& a *o!n&ra%!,s an% +ea3es !& a& a *o!n&

of &he sa)e ra%!,s.of &he sa)e ra%!,s.




4-Ra%!a+ 'o( 5Cen&r!f,ga+6 )a$h!nes (here4-Ra%!a+ 'o( 5Cen&r!f,ga+6 )a$h!nes (here

&he (or2!ng ',!% )o3es !ns!%e &he !)*e++er !n&he (or2!ng ',!% )o3es !ns!%e &he !)*e++er !n

a %!re$&!on nor)a+ &o &he !)*e++er a1!s.a %!re$&!on nor)a+ &o &he !)*e++er a1!s.

Therefore &he ',!% en&ers &heTherefore &he ',!% en&ers &he

!)*e++er a& a *o!n& of $er&a!n!)*e++er a& a *o!n& of $er&a!n

ra%!,s an% +ea3es !& a& a *o!n&ra%!,s an% +ea3es !& a& a *o!n&

of %!7eren& ra%!,s.of %!7eren& ra%!,s.




8-M!1e% 'o( )a$h!nes (here &he (or2!ng8-M!1e% 'o( )a$h!nes (here &he (or2!ng',!% )o3es !ns!%e &he !)*e++er !n a %!re$&!on',!% )o3es !ns!%e &he !)*e++er !n a %!re$&!onne!&her nor)a+ nor *ara++e+ &o &he !)*e++erne!&her nor)a+ nor *ara++e+ &o &he !)*e++era1!s. Therefore &hea1!s. Therefore &he

',!% en&ers &he !)*e++er a& a',!% en&ers &he !)*e++er a& a

*o!n& of $er&a!n ra%!,s an% +ea3es*o!n& of $er&a!n ra%!,s an% +ea3es!& a& a *o!n& of %!7eren& ra%!,s.!& a& a *o!n& of %!7eren& ra%!,s.

The fo++o(!ng g,re !s aThe fo++o(!ng g,re !s a

%!agra))a&!$ s2e&$h for &hese%!agra))a&!$ s2e&$h for &hese

&hree &y*es of ro&o%yna)!$&hree &y*es of ro&o%yna)!$5$on&!n,o,s 'o(6 )a$h!ne5$on&!n,o,s 'o(6 )a$h!ne




CENTRIFU#AL PUMP




CENTRIFU#AL FORCE




Cen&r!f,ga+ P,)*Cen&r!f,ga+ P,)*

The genera+ $o)*onen&s 9o&h s&a&!onary an%The genera+ $o)*onen&s 9o&h s&a&!onary an%

ro&ary are %e*!$&e% !n F!g,re 9e+o( .ro&ary are %e*!$&e% !n F!g,re 9e+o( .

The )a!n $o)*onen&s are %!s$,sse% !n 9r!efThe )a!n $o)*onen&s are %!s$,sse% !n 9r!ef

9e+o(. F!g,re 9e+o( sho(s &hese *ar&s on a9e+o(. F!g,re 9e+o( sho(s &hese *ar&s on a

*ho&ogra*h of a *,)* !n &he e+%.*ho&ogra*h of a *,)* !n &he e+%.




#enera+ $o)*onen&s of Cen&r!f,ga+ P,)*




General components of Centrifugal Pump




Wor2!ng Me$han!s) of aWor2!ng Me$han!s) of aCen&r!f,ga+ P,)*Cen&r!f,ga+ P,)*

A $en&r!f,ga+ *,)* !s one of &he s!)*+es&A $en&r!f,ga+ *,)* !s one of &he s!)*+es&

*!e$es of e:,!*)en& !n any *ro$ess *+an& an%*!e$es of e:,!*)en& !n any *ro$ess *+an& an%

a& &he sa)e &!)e &he )os& sens!&!3e. I&sa& &he sa)e &!)e &he )os& sens!&!3e. I&s

*,r*ose !s &o $on3er& energy of a *r!)e )o3er*,r*ose !s &o $on3er& energy of a *r!)e )o3er

5an e+e$&r!$ )o&or or &,r9!ne6 rs& !n&o5an e+e$&r!$ )o&or or &,r9!ne6 rs& !n&o3e+o$!&y or 2!ne&!$ energy an% &hen !n&o3e+o$!&y or 2!ne&!$ energy an% &hen !n&o

*ress,re energy of a ',!% &ha& !s 9e!ng*ress,re energy of a ',!% &ha& !s 9e!ng

*,)*e%. The energy $hanges o$$,r 9y 3!r&,e*,)*e%. The energy $hanges o$$,r 9y 3!r&,e

of &(o )a!n *ar&s of &he *,)* &he !)*e++erof &(o )a!n *ar&s of &he *,)* &he !)*e++eran% &he 3o+,&e or %!7,ser.an% &he 3o+,&e or %!7,ser.




The !)*e++er !s &he ro&a&!ng *ar& &ha& $on3er&sThe !)*e++er !s &he ro&a&!ng *ar& &ha& $on3er&s

%r!3er energy !n&o &he 2!ne&!$ energy. The%r!3er energy !n&o &he 2!ne&!$ energy. The

3o+,&e or %!7,ser !s &he s&a&!onary *ar& &ha&3o+,&e or %!7,ser !s &he s&a&!onary *ar& &ha&

$on3er&s &he 2!ne&!$ energy !n&o *ress,re$on3er&s &he 2!ne&!$ energy !n&o *ress,re

energy.energy.

No&e/ A++ of &he for)s of energy !n3o+3e% !n aNo&e/ A++ of &he for)s of energy !n3o+3e% !n a

+!:,!% 'o( sys&e) are e1*resse% !n &er)s of+!:,!% 'o( sys&e) are e1*resse% !n &er)s of

)e&ers of +!:,!% !.e. hea%.)e&ers of +!:,!% !.e. hea%.




#enera&!on of Cen&r!f,ga+ For$e#enera&!on of Cen&r!f,ga+ For$e

The *ro$ess +!:,!% en&ers &he s,$&!on no""+e an%The *ro$ess +!:,!% en&ers &he s,$&!on no""+e an%&hen !n&o &he eye 5$en&re6 of a re3o+3!ng %e3!$e&hen !n&o &he eye 5$en&re6 of a re3o+3!ng %e3!$e2no(n as &he !)*e++er. When &he !)*e++er2no(n as &he !)*e++er. When &he !)*e++erro&a&es !& s*!ns &he +!:,!% s!&&!ng !n &he $a3!&!esro&a&es !& s*!ns &he +!:,!% s!&&!ng !n &he $a3!&!es9e&(een &he 3anes o,&(ar% an% *ro3!%es9e&(een &he 3anes o,&(ar% an% *ro3!%es

$en&r!f,ga+ a$$e+era&!on.$en&r!f,ga+ a$$e+era&!on.As +!:,!% +ea3es &he eye of &he !)*e++er a +o(-As +!:,!% +ea3es &he eye of &he !)*e++er a +o(-*ress,re area !s $rea&e% $a,s!ng )ore +!:,!% &o*ress,re area !s $rea&e% $a,s!ng )ore +!:,!% &o'o( &o(ar%s &he !n+e&. Be$a,se &he !)*e++er'o( &o(ar%s &he !n+e&. Be$a,se &he !)*e++er9+a%es are $,r3e% &he ',!% !s *,she% !n a9+a%es are $,r3e% &he ',!% !s *,she% !n a

&angen&!a+ an% ra%!a+ %!re$&!on 9y &he $en&r!f,ga+&angen&!a+ an% ra%!a+ %!re$&!on 9y &he $en&r!f,ga+for$e.for$e.F!g,re. 8 9e+o( %e*!$&s a s!%e $ross-se$&!on of aF!g,re. 8 9e+o( %e*!$&s a s!%e $ross-se$&!on of a$en&r!f,ga+ *,)* !n%!$a&!ng &he )o3e)en& of &he$en&r!f,ga+ *,)* !n%!$a&!ng &he )o3e)en& of &he+!:,!%.+!:,!%.




F!g,re 8 L!:,!% 'o( *a&h !ns!%e a $en&r!f,ga+F!g,re 8 L!:,!% 'o( *a&h !ns!%e a $en&r!f,ga+*,)**,)*

Con3ers!on of ;!ne&!$ Energy &o Press,re EnergyCon3ers!on of ;!ne&!$ Energy &o Press,re Energy




Pump RelationshipsPump Relationships

The 2ey !%ea !s &ha& &he energy $rea&e% 9y &heThe 2ey !%ea !s &ha& &he energy $rea&e% 9y &he$en&r!f,ga+ for$e !s$en&r!f,ga+ for$e !s kinetic energy kinetic energy . The a)o,n& of. The a)o,n& ofenergy g!3en &o &he +!:,!% !s *ro*or&!ona+ &o &heenergy g!3en &o &he +!:,!% !s *ro*or&!ona+ &o &hevelocityvelocity a& &he e%ge or 3ane &!* of &he !)*e++er. Thea& &he e%ge or 3ane &!* of &he !)*e++er. Thefas&er &he !)*e++er re3o+3es or &he 9!gger &hefas&er &he !)*e++er re3o+3es or &he 9!gger &he

!)*e++er !s &hen &he h!gher (!++ 9e &he 3e+o$!&y of &he!)*e++er !s &hen &he h!gher (!++ 9e &he 3e+o$!&y of &he+!:,!% a& &he 3ane &!* an% &he grea&er &he energy+!:,!% a& &he 3ane &!* an% &he grea&er &he energy!)*ar&e% &o &he +!:,!%.!)*ar&e% &o &he +!:,!%.

Th!s 2!ne&!$ energy of a +!:,!% $o)!ng o,& of anTh!s 2!ne&!$ energy of a +!:,!% $o)!ng o,& of an!)*e++er !s harnesse% 9y $rea&!ng a!)*e++er !s harnesse% 9y $rea&!ng a resistanceresistance &o &he&o &he

'o(. The rs& res!s&an$e !s $rea&e% 9y &he *,)*'o(. The rs& res!s&an$e !s $rea&e% 9y &he *,)*3o+,&e 5$as!ng6 &ha& $a&$hes &he +!:,!% an% s+o(s !&3o+,&e 5$as!ng6 &ha& $a&$hes &he +!:,!% an% s+o(s !&%o(n. In &he %!s$harge no""+e &he +!:,!% f,r&her%o(n. In &he %!s$harge no""+e &he +!:,!% f,r&her%e$e+era&es an% !&s 3e+o$!&y !s $on3er&e% &o *ress,re%e$e+era&es an% !&s 3e+o$!&y !s $on3er&e% &o *ress,rea$$or%!ng &o Berno,++!<s *r!n$!*+e.a$$or%!ng &o Berno,++!<s *r!n$!*+e.




(cont’d)(cont’d)

Therefore &he hea% 5*ress,re !n &er)s of he!gh&Therefore &he hea% 5*ress,re !n &er)s of he!gh&

of +!:,!%6 %e3e+o*e% !s a**ro1!)a&e+y e:,a+ &o &heof +!:,!%6 %e3e+o*e% !s a**ro1!)a&e+y e:,a+ &o &he

3e+o$!&y energy a& &he *er!*hery of &he !)*e++er3e+o$!&y energy a& &he *er!*hery of &he !)*e++er

e1*resse% 9y &he fo++o(!ng (e++-2no(n for),+a/e1*resse% 9y &he fo++o(!ng (e++-2no(n for),+a/

H=VH=V 22 /2g /2g

wherewhere !s &he &o&a+ hea% %e3e+o*e% !n !s &he &o&a+ hea% %e3e+o*e% !n mm

V V !s &he s*ee% a& &he *er!*hery of &he !)*e++er!s &he s*ee% a& &he *er!*hery of &he !)*e++er!n!n m/sm/s

gg !s &he a$$e+era&!on %,e &o gra3!&y !n!s &he a$$e+era&!on %,e &o gra3!&y !n m/sm/s22




A han%y for),+a for *er!*hera+ 3e+o$!&y !s/A han%y for),+a for *er!*hera+ 3e+o$!&y !s/

V=ND/ 754V=ND/ 754

wherewhere N is the rotational speed in rpmN is the rotational speed in rpm

D is the impeller diameter in mD is the impeller diameter in m

This head can also e calc!lated "rom the readingsThis head can also e calc!lated "rom the readings

on the press!re ga!ges attached to the s!ctionon the press!re ga!ges attached to the s!ction

and discharge lines# $!mp c!rves relate %ow rateand discharge lines# $!mp c!rves relate %ow rateand press!re &head' developed y the p!mp atand press!re &head' developed y the p!mp at

di(erent impeller si)es and rotational speeds#di(erent impeller si)es and rotational speeds#




The $en&r!f,ga+ *,)* o*era&!on sho,+%The $en&r!f,ga+ *,)* o*era&!on sho,+%

$onfor) &o &he *,)* $,r3es s,**+!e% 9y &he$onfor) &o &he *,)* $,r3es s,**+!e% 9y &he

)an,fa$&,rer. In or%er &o rea% an%)an,fa$&,rer. In or%er &o rea% an%

,n%ers&an% &he *,)* $,r3es !& !s 3ery,n%ers&an% &he *,)* $,r3es !& !s 3ery

!)*or&an& &o %e3e+o* a $+ear ,n%ers&an%!ng of!)*or&an& &o %e3e+o* a $+ear ,n%ers&an%!ng of&he &er)s ,se% !n &he $,r3es. Th!s &o*!$ (!++&he &er)s ,se% !n &he $,r3es. Th!s &o*!$ (!++

9e $o3ere% +a&er.9e $o3ere% +a&er.

One fa$& &ha& ),s& a+(ays 9e re)e)9ere%/One fa$& &ha& ),s& a+(ays 9e re)e)9ere%/

A *,)* %oes no& $rea&e *ress,re !& on+yA *,)* %oes no& $rea&e *ress,re !& on+y*ro3!%es 'o(. Press,re !s a =,s& an !n%!$a&!on*ro3!%es 'o(. Press,re !s a =,s& an !n%!$a&!on

of &he a)o,n& of res!s&an$e &o 'o(.of &he a)o,n& of res!s&an$e &o 'o(.




General Component ofGeneral Component of Centrifugal PumpCentrifugal Pump

A $en&r!f,ga+ *,)* has &(o )a!n $o)*onen&s/A $en&r!f,ga+ *,)* has &(o )a!n $o)*onen&s/

0-A s&a&!onary $o)*onen& $o)*r!se% of a0-A s&a&!onary $o)*onen& $o)*r!se% of a

$as!ng $as!ng $o3er an% 9ear!ngs.$as!ng $as!ng $o3er an% 9ear!ngs.

4-A ro&a&!ng $o)*onen& $o)*r!se% of an4-A ro&a&!ng $o)*onen& $o)*r!se% of an

!)*e++er an% a shaf&!)*e++er an% a shaf&




S&a&!onary Co)*onen&sS&a&!onary Co)*onen&s5Cas!ng65Cas!ng6

Cas!ngs are genera++y of &(o &y*es/ 3o+,&e an%Cas!ngs are genera++y of &(o &y*es/ 3o+,&e an%

$!r$,+ar. The !)*e++ers are &&e% !ns!%e &he$!r$,+ar. The !)*e++ers are &&e% !ns!%e &he

$as!ngs.$as!ngs.

0.0. Vol!te casingsVol!te casings// 9,!+% a h!gher hea%>9,!+% a h!gher hea%> circ!larcirc!lar

casingscasings are ,se% for +o( hea% an% h!gh $a*a$!&y.are ,se% for +o( hea% an% h!gh $a*a$!&y.

AA vol!tevol!te !s a $,r3e% f,nne+ !n$reas!ng !n area &o!s a $,r3e% f,nne+ !n$reas!ng !n area &o

&he %!s$harge *or& as sho(n !n &he fo++o(!ng&he %!s$harge *or& as sho(n !n &he fo++o(!ng

g,re .g,re .

As &he area of &he $ross-se$&!on !n$reases &heAs &he area of &he $ross-se$&!on !n$reases &he3o+,&e re%,$es &he s*ee% of &he +!:,!% an%3o+,&e re%,$es &he s*ee% of &he +!:,!% an%

!n$reases &he *ress,re of &he +!:,!%.!n$reases &he *ress,re of &he +!:,!%.




C,&-a(ay of a *,)* sho(!ng 3o+,&e $as!ng




One of &heOne of &he main p!rposes o" a vol!te casingmain p!rposes o" a vol!te casing !s!s

&o he+* 9a+an$e &he hy%ra,+!$ *ress,re on &he&o he+* 9a+an$e &he hy%ra,+!$ *ress,re on &he

shaf& of &he *,)*. o(e3er &h!s o$$,rs 9es&shaf& of &he *,)*. o(e3er &h!s o$$,rs 9es&

a& &he )an,fa$&,rer?s re$o))en%e% $a*a$!&y.a& &he )an,fa$&,rer?s re$o))en%e% $a*a$!&y.

R,nn!ng 3o+,&e-s&y+e *,)*s a& a +o(erR,nn!ng 3o+,&e-s&y+e *,)*s a& a +o(er$a*a$!&y &han &he )an,fa$&,rer re$o))en%s$a*a$!&y &han &he )an,fa$&,rer re$o))en%s

$an *,& +a&era+ s&ress on &he shaf& of &he$an *,& +a&era+ s&ress on &he shaf& of &he

*,)* !n$reas!ng (ear-an%-&ear on &he sea+s*,)* !n$reas!ng (ear-an%-&ear on &he sea+s

an% 9ear!ngs an% on &he shaf& !&se+f. Do,9+e-an% 9ear!ngs an% on &he shaf& !&se+f. Do,9+e-3o+,&e $as!ngs are ,se% (hen &he ra%!a+3o+,&e $as!ngs are ,se% (hen &he ra%!a+

&hr,s&s 9e$o)e s!gn!$an& a& re%,$e%&hr,s&s 9e$o)e s!gn!$an& a& re%,$e%

$a*a$!&!es.$a*a$!&!es.




C!r$,+ar $as!ng 5D!7,serC!r$,+ar $as!ng 5D!7,ser$as!ng6/$as!ng6/

C!r$,+ar $as!ng-D!7,ser $as!ng> ha3eC!r$,+ar $as!ng-D!7,ser $as!ng> ha3e

s&a&!onary %!7,s!on 3anes s,rro,n%!ng &hes&a&!onary %!7,s!on 3anes s,rro,n%!ng &he

!)*e++er *er!*hery &ha& $on3er& 3e+o$!&y!)*e++er *er!*hery &ha& $on3er& 3e+o$!&y

energy &o *ress,re energy. Con3en&!ona++yenergy &o *ress,re energy. Con3en&!ona++y

&he %!7,sers are a**+!e% &o ),+&!-s&age&he %!7,sers are a**+!e% &o ),+&!-s&age*,)*s. The $as!ngs $an 9e %es!gne% e!&her as*,)*s. The $as!ngs $an 9e %es!gne% e!&her as

so+!% $as!ngs or s*+!& $as!ngs.so+!% $as!ngs or s*+!& $as!ngs.




So+!% $as!ngSo+!% $as!ng

So+!% $as!ng !)*+!es a %es!gn !n (h!$h &heSo+!% $as!ng !)*+!es a %es!gn !n (h!$h &he

en&!re $as!ng !n$+,%!ng &he %!s$harge no""+e !sen&!re $as!ng !n$+,%!ng &he %!s$harge no""+e !s

a++ $on&a!ne% !n one $as&!ng or fa9r!$a&e%a++ $on&a!ne% !n one $as&!ng or fa9r!$a&e%

*!e$e. S*+!& $as!ng !)*+!es &(o or )ore *ar&s*!e$e. S*+!& $as!ng !)*+!es &(o or )ore *ar&s

are fas&ene% &oge&her. When &he $as!ng *ar&sare fas&ene% &oge&her. When &he $as!ng *ar&sare %!3!%e% 9y hor!"on&a+ *+ane &he $as!ng !sare %!3!%e% 9y hor!"on&a+ *+ane &he $as!ng !s

%es$r!9e% as hor!"on&a++y s*+!& or a1!a++y s*+!&%es$r!9e% as hor!"on&a++y s*+!& or a1!a++y s*+!&

$as!ng. When &he s*+!& !s !n a 3er&!$a+ *+ane$as!ng. When &he s*+!& !s !n a 3er&!$a+ *+ane

*er*en%!$,+ar &o &he ro&a&!on a1!s &he $as!ng*er*en%!$,+ar &o &he ro&a&!on a1!s &he $as!ng!s %es$r!9e% as 3er&!$a++y s*+!& or ra%!a++y s*+!&!s %es$r!9e% as 3er&!$a++y s*+!& or ra%!a++y s*+!&

$as!ng. Cas!ng Wear r!ngs a$& as &he sea+$as!ng. Cas!ng Wear r!ngs a$& as &he sea+

9e&(een &he $as!ng an% &he !)*e++er.9e&(een &he $as!ng an% &he !)*e++er.




So+!% Cas!ngSo+!% Cas!ng




S,$&!on an% D!s$harge No""+eS,$&!on an% D!s$harge No""+e

The s,$&!on an% %!s$harge no""+es are *ar& ofThe s,$&!on an% %!s$harge no""+es are *ar& of&he $as!ngs !&se+f. They $o))on+y ha3e &he&he $as!ngs !&se+f. They $o))on+y ha3e &hefo++o(!ng $ong,ra&!ons.fo++o(!ng $ong,ra&!ons.

0.0. *nd s!ction/Top discharge*nd s!ction/Top discharge - The s,$&!on- The s,$&!onno""+e !s +o$a&e% a& &he en% of an% $on$en&r!$no""+e !s +o$a&e% a& &he en% of an% $on$en&r!$&o &he shaf& (h!+e &he %!s$harge no""+e !s&o &he shaf& (h!+e &he %!s$harge no""+e !s+o$a&e% a& &he &o* of &he $ase *er*en%!$,+ar+o$a&e% a& &he &o* of &he $ase *er*en%!$,+ar&o &he shaf&. Th!s *,)* !s a+(ays of an&o &he shaf&. Th!s *,)* !s a+(ays of ano3erh,ng &y*e an% &y*!$a++y has +o(er NPSro3erh,ng &y*e an% &y*!$a++y has +o(er NPSr9e$a,se &he +!:,!% fee%s %!re$&+y !n&o &he9e$a,se &he +!:,!% fee%s %!re$&+y !n&o &he!)*e++er eye.!)*e++er eye.




4.4. Top s!ction Top discharge no))leTop s!ction Top discharge no))le -The-The

s,$&!on an% %!s$harge no""+es are +o$a&e% a&s,$&!on an% %!s$harge no""+es are +o$a&e% a&

&he &o* of &he $ase *er*en%!$,+ar &o &he shaf&.&he &o* of &he $ase *er*en%!$,+ar &o &he shaf&.

Th!s *,)* $an e!&her 9e an o3erh,ng &y*e orTh!s *,)* $an e!&her 9e an o3erh,ng &y*e or

9e&(een-9ear!ng &y*e 9,& !s a+(ays a ra%!a++y9e&(een-9ear!ng &y*e 9,& !s a+(ays a ra%!a++ys*+!& $ase *,)*.s*+!& $ase *,)*.




S,$&!on an% D!s$harge No""+e Lo$a&!onsS,$&!on an% D!s$harge No""+e Lo$a&!ons




+ide s!ction / +ide discharge+ide s!ction / +ide dischargeno))lesno))les

8. +ide s!ction / +ide discharge no))les - hesuction and discharge nozzles are located at thesides of the case perpendicular to the shaft. hispump can ha!e either an a"ially or radially splitcase type.

Sea+ Cha)9er an% S&,@ng Bo1/ #eal cham$erand #tu%ng $o" $oth refer to a cham$er& eitherintegral 'ith or separate from the pump casehousing that forms the region $et'een the shaftand casing 'here sealing media are installed. henthe sealing is achie!ed $y means of a mechanicalseal& the cham$er is commonly referred to as a #ealCham$er.




Par&s of a s!)*+e Sea+ Cha)9er




When &he sea+!ng !s a$h!e3e% 9y )eans of *a$2!ngWhen &he sea+!ng !s a$h!e3e% 9y )eans of *a$2!ng

&he $ha)9er !s referre% &o as a S&,@ng Bo1. Bo&h&he $ha)9er !s referre% &o as a S&,@ng Bo1. Bo&h&he sea+ $ha)9er an% &he s&,@ng 9o1 ha3e &he&he sea+ $ha)9er an% &he s&,@ng 9o1 ha3e &he*r!)ary f,n$&!on of *ro&e$&!ng &he *,)* aga!ns&*r!)ary f,n$&!on of *ro&e$&!ng &he *,)* aga!ns&+ea2age a& &he *o!n& (here &he shaf& *asses o,&+ea2age a& &he *o!n& (here &he shaf& *asses o,&&hro,gh &he *,)* *ress,re $as!ng.&hro,gh &he *,)* *ress,re $as!ng.

When &he *ress,re a& &he 9o&&o) of &he $ha)9er !sWhen &he *ress,re a& &he 9o&&o) of &he $ha)9er !s

9e+o( a&)os*her!$ !& *re3en&s a!r +ea2age !n&o &he9e+o( a&)os*her!$ !& *re3en&s a!r +ea2age !n&o &he*,)*. When &he *ress,re !s a9o3e a&)os*her!$ &he*,)*. When &he *ress,re !s a9o3e a&)os*her!$ &he$ha)9ers *re3en& +!:,!% +ea2age o,& of &he *,)*.$ha)9ers *re3en& +!:,!% +ea2age o,& of &he *,)*.

The sea+ $ha)9ers an% s&,@ng 9o1es are a+soThe sea+ $ha)9ers an% s&,@ng 9o1es are a+so*ro3!%e% (!&h $oo+!ng or hea&!ng arrange)en& for*ro3!%e% (!&h $oo+!ng or hea&!ng arrange)en& for*ro*er &e)*era&,re $on&ro+. The g,re 9e+o(*ro*er &e)*era&,re $on&ro+. The g,re 9e+o(

%e*!$&s an e1&erna++y )o,n&e% sea+ $ha)9er an% !&s%e*!$&s an e1&erna++y )o,n&e% sea+ $ha)9er an% !&s*ar&s.*ar&s.




#+an%/ The g+an% !s a 3ery !)*or&an& *ar& of &he sea+#+an%/ The g+an% !s a 3ery !)*or&an& *ar& of &he sea+$ha)9er or &he s&,@ng 9o1. I& g!3es &he *a$2!ngs or$ha)9er or &he s&,@ng 9o1. I& g!3es &he *a$2!ngs or&he )e$han!$a+ sea+ &he %es!re% & on &he shaf&&he )e$han!$a+ sea+ &he %es!re% & on &he shaf&s+ee3e. I& $an 9e eas!+y a%=,s&e% !n a1!a+ %!re$&!on.s+ee3e. I& $an 9e eas!+y a%=,s&e% !n a1!a+ %!re$&!on.The g+an% $o)*r!ses of &he sea+ ',sh :,en$hThe g+an% $o)*r!ses of &he sea+ ',sh :,en$h$oo+!ng %ra!n an% 3en& $onne$&!on *or&s as *er &he$oo+!ng %ra!n an% 3en& $onne$&!on *or&s as *er &hes&an%ar% $o%es +!2e API 4.s&an%ar% $o%es +!2e API 4.

Throa& B,sh!ng/ The 9o&&o) or !ns!%e en% of &heThroa& B,sh!ng/ The 9o&&o) or !ns!%e en% of &he$ha)9er !s *ro3!%e% (!&h a s&a&!onary %e3!$e $a++e%$ha)9er !s *ro3!%e% (!&h a s&a&!onary %e3!$e $a++e%&hroa& 9,sh!ng &ha& for)s a res&r!$&!3e $+ose&hroa& 9,sh!ng &ha& for)s a res&r!$&!3e $+ose$+earan$e aro,n% &he s+ee3e 5or shaf&6 9e&(een &he$+earan$e aro,n% &he s+ee3e 5or shaf&6 9e&(een &hesea+ an% &he !)*e++er.sea+ an% &he !)*e++er.

Thro&&+e 9,sh!ng refers &o a %e3!$e &ha& for)s aThro&&+e 9,sh!ng refers &o a %e3!$e &ha& for)s ares&r!$&!3e $+ose $+earan$e aro,n% &he s+ee3e 5orres&r!$&!3e $+ose $+earan$e aro,n% &he s+ee3e 5orshaf&6 a& &he o,&9oar% en% of a )e$han!$a+ sea+shaf&6 a& &he o,&9oar% en% of a )e$han!$a+ sea+g+an%.g+an%.




In&erna+ $!r$,+a&!ng %e3!$e refers &o %e3!$e +o$a&e%In&erna+ $!r$,+a&!ng %e3!$e refers &o %e3!$e +o$a&e%

!n &he sea+ $ha)9er &o $!r$,+a&e sea+ $ha)9er ',!%!n &he sea+ $ha)9er &o $!r$,+a&e sea+ $ha)9er ',!%&hro,gh a $oo+er or 9arr!er9,7er ',!% reser3o!r.&hro,gh a $oo+er or 9arr!er9,7er ',!% reser3o!r.Us,a++y !& !s referre% &o as a *,)*!ng r!ng.Us,a++y !& !s referre% &o as a *,)*!ng r!ng.

Bear!ng 9ra$2e&/ The 9ear!ng 9ra$2e& en$+oses &heBear!ng 9ra$2e&/ The 9ear!ng 9ra$2e& en$+oses &he9ear!ngs )o,n&e% on &he shaf&. The 9ear!ngs 2ee*9ear!ngs )o,n&e% on &he shaf&. The 9ear!ngs 2ee*&he shaf& or ro&or !n $orre$& a+!gn)en& (!&h &he&he shaf& or ro&or !n $orre$& a+!gn)en& (!&h &he

s&a&!onary *ar&s ,n%er &he a$&!on of ra%!a+ an%s&a&!onary *ar&s ,n%er &he a$&!on of ra%!a+ an%&rans3erse +oa%s. The 9ear!ng 9ra$2e& a+so&rans3erse +oa%s. The 9ear!ng 9ra$2e& a+so!n$+,%es an o!+ reser3o!r for +,9r!$a&!on $ons&an&!n$+,%es an o!+ reser3o!r for +,9r!$a&!on $ons&an&+e3e+ of o!+ =a$2e& for $oo+!ng 9y $!r$,+a&!ng+e3e+ of o!+ =a$2e& for $oo+!ng 9y $!r$,+a&!ng$oo+!ng (a&er.$oo+!ng (a&er.

Sea+!ng 9e&(een &he 9ear!ng 9ra$2e& an% &he shaf&Sea+!ng 9e&(een &he 9ear!ng 9ra$2e& an% &he shaf&!s a$h!e3e% !n &he fo++o(!ng (ays/!s a$h!e3e% !n &he fo++o(!ng (ays/L!* sea+s - La9yr!n&h r!ngs -Bear!ng !so+a&orsL!* sea+s - La9yr!n&h r!ngs -Bear!ng !so+a&ors




L!* sea+s/ Th!s !s an asse)9+y $ons!s&!ng of a r,99!ngL!* sea+s/ Th!s !s an asse)9+y $ons!s&!ng of a r,99!nge+e)en& he+% !n *+a$e 9y s*r!ng. The sea+ (or2s ase+e)en& he+% !n *+a$e 9y s*r!ng. The sea+ (or2s as

an o!+ +) !s genera&e% 9e&(een &he +!* of &he sea+an o!+ +) !s genera&e% 9e&(een &he +!* of &he sea+an% &he shaf&. Any %a)age &o &he shaf& (here &hean% &he shaf&. Any %a)age &o &he shaf& (here &hesea+ r,ns (!++ $a,se +ea2age 9e$a,se &he o*&!),) o!+sea+ r,ns (!++ $a,se +ea2age 9e$a,se &he o*&!),) o!++) &h!$2ness (!++ 9e e1$ee%e% +o$a++y. So shaf&+) &h!$2ness (!++ 9e e1$ee%e% +o$a++y. So shaf&n!sh !s es*e$!a++y !)*or&an& as +ea2age (!++ o$$,r !fn!sh !s es*e$!a++y !)*or&an& as +ea2age (!++ o$$,r !fan !rreg,+ar s,rfa$e !s *resen&. The r,99!ng *ro3!%esan !rreg,+ar s,rfa$e !s *resen&. The r,99!ng *ro3!%es&he sea+!ng a$&!on so $an no& 9e ,se% a& h!gh s*ee%s&he sea+!ng a$&!on so $an no& 9e ,se% a& h!gh s*ee%sas &o )a!n&a!n o!+ +) &h!$2ness &he sea+ ),s& fo++o(as &o )a!n&a!n o!+ +) &h!$2ness &he sea+ ),s& fo++o(any shaf& )o3e)en&. Th!s 9e$o)es %!@$,+& (henany shaf& )o3e)en&. Th!s 9e$o)es %!@$,+& (hen&he shaf& !s s,9=e$& &o e$$en&r!$ r,nn!ng or 3!9ra&!on&he shaf& !s s,9=e$& &o e$$en&r!$ r,nn!ng or 3!9ra&!ona& h!gh s*ee%s. Ty*!$a++y &hese sea+s (!++ o*era&e !na& h!gh s*ee%s. Ty*!$a++y &hese sea+s (!++ o*era&e !n

&he reg!on of 0 )s as &he sea+s are a7e$&e% 9y&he reg!on of 0 )s as &he sea+s are a7e$&e% 9yfr!$&!on.fr!$&!on.




L!* sea+s





La9yr!n&h r!ngs/ a$yrinth seals operate 'ith positi!eclearance and pro!ide sealing $y !irtue of a lengthy&tortuous gap path. hey are used in high-speedapplications 'ith either oil or grease. #ealing depends onthe form of the la$yrinth gap and the length of the

lea*age path. Rings on the shaft and groo!es in thehousing pro!ide the $asic la$yrinth. +t least three gro!esshould $e used to pro!ide ade,uate sealing clearances!ary $et'een ./0 to 1. mm& depending on the speedand temperature the seal is operating. More e%cientforms of la$yrinth seal use alternating teeth of alternatingserrations. he e%ciency of a la$yrinth seal increases inin!erse proportion to& so smaller gaps produce lesslea*age $ut the gap has to $e large enough to a!oidcontact. Contact could $e tolerated 'hen the material incontact su$limates pre!enting damage.




a$yrinth rings





Bear!ng !so+a&ors/ + $earing isolator is a non-contact& non-'earing& permanent $earing protectionde!ice. 2t has a rotor and a stator& and the t'o areunitized& so that they don’t separate from one

another 'hile in use. ypically& the rotor turns 'ith arotating shaft& 'hile the stator is pressed into a$earing housing. he t'o components interact to*eep contamination out of the $earing enclosure

and the lu$ricant in.




4. Ro&a&!ng Co)*onen&s4. Ro&a&!ng Co)*onen&s5I)*e++er65I)*e++er6

he impeller is the main rotating part that pro!idesthe centrifugal acceleration to the 3uid. hey areoften classi4ed in many 'ays.

,ased on ma-or direction o" %ow in re"erenceto the a.is o" rotation

Radial 3o'+"ial 3o'Mi"ed 3o'

,ased on s!ction type

#ingle-suction5 i,uid inlet on one side.6ou$le-suction5 i,uid inlet to the impeller

symmetrically from $oth sides.





,ased on mechanical constr!ction

Closed5 #hrouds or side'all enclosing the !anes.

7pen5 8o shrouds or 'all to enclose the !anes.

#emi-open or !orte" type.




Closed type 2mpeller




7pen type impellers




Par&s of a C+ose% I)*e++er




Closed impellers re,uire 'ear rings and these 'earrings present another maintenance pro$lem. 7pen andsemi-open impellers are less li*ely to clog& $ut needmanual ad9ustment to the !olute or $ac*-plate to getthe proper impeller setting and pre!ent internal re-

circulation. :orte" pump impellers are great for solidsand ;stringy; materials $ut they are up to 0< lesse%cient than con!entional designs. he num$er ofimpellers determines the num$er of stages of thepump. + single stage pump has one impeller only and is

$est for lo' head ser!ice. + t'o-stage pump has t'oimpellers in series for medium head ser!ice. + multi-stage pump has three or more impellers in series forhigh head ser!ice




Wear r!ngs/ ear ring pro!ides an easily andeconomically rene'a$le lea*age 9oint $et'een theimpeller and the casing. 2f the clearance $ecomes toolarge the pump e%ciency 'ill $e lo'ered causing heatand !i$ration pro$lems. Most manufacturers re,uire that

you disassem$le the pump to chec* the 'ear ringclearance and replace the rings 'hen this clearancedou$les.

Shaf&/ he $asic purpose of a centrifugal pump shaft isto transmit the tor,ues encountered 'hen starting and

during operation 'hile supporting the impeller and otherrotating parts. 2t must do this 9o$ 'ith a de3ection lessthan the minimum clearance $et'een the rotating andstationary parts.




Shaf& S+ee3e/ Pump shafts are usually protectedfrom erosion& corrosion& and 'ear at the sealcham$ers& lea*age 9oints& internal $earings& and inthe 'ater'ays $y rene'a$le slee!es. =nless

other'ise speci4ed& a shaft slee!e of 'ear&corrosion& and erosion resistant material shall $epro!ided to protect the shaft. he slee!e shall $esealed at one end. he shaft slee!e assem$ly shalle"tend $eyond the outer face of the seal gland

plate. (ea*age $et'een the shaft and the slee!eshould not $e confused 'ith lea*age through themechanical seal).




+ !ie' of a shaft slee!e




P=MP #H+> ? 2MP@@R AP@#




Co,*+!ng/ Couplings can compensate for a"ial gro'th ofthe shaft and transmit tor,ue to the impeller. #haftcouplings can $e $roadly classi4ed into t'o groups5 rigidand 3e"i$le. Rigid couplings are used in applications'here there is a$solutely no possi$ility or room for anymisalignment. >le"i$le shaft couplings are more prone toselection& installation and maintenance errors. >le"i$le

shaft couplings can $e di!ided into t'o $asic groups5elastomeric and non-elastomeric5

*lastomeric co!plings use either ru$$er or polymerelements to achie!e 3e"i$ility. hese elements can either$e in shear or in compression. ire and ru$$er slee!e

designs are elastomer in shear couplings 9a' and pin and$ushing designs are elastomer in compression couplings.




Nonelastomeric co!plings use metallic elementsto o$tain 3e"i$ility. hese can $e one of t'o types5lu$ricated or nonlu$ricated. u$ricated designsaccommodate misalignment $y the sliding action oftheir components& hence the need for lu$rication.

he non-lu$ricated designs accommodatemisalignment through 3e"ing. Gear& grid and chaincouplings are e"amples of non-elastomeric&lu$ricated couplings. 6isc and diaphragm couplings

are non-elastomeric and nonlu$ricated.




Coupling




A,1!+!ary Co)*onen&s/ +u"iliary components generallyinclude the follo'ing piping systems for the follo'ingser!ices5

#eal 3ushing & cooling & ,uenching systems

#eal drains and !ents

Bearing lu$rication & cooling systems#eal cham$er or stu%ng $o" cooling& heating systems

Pump pedestal cooling systems

+u"iliary piping systems include tu$ing& piping& isolating!al!es& control !al!es& relief !al!es& temperature gaugesand thermocouples& pressure gauges& sight 3o' indicators&ori4ces& seal 3ush coolers& dual seal $arrier$uDer 3uidreser!oirs& and all related !ents and drains. +P2E1 and+P2 EF/ pro!ide guidelines for all au"iliary connections.




6e4nition of 2mportant terms6e4nition of 2mportant terms

he *ey performance parameters of centrifugalpumps are capacity& head& BHP (Bra*e horsepo'er)& B@P (Best e%ciency point) and speci4cspeed. he pump cur!es pro!ide the operating'indo' 'ithin 'hich these parameters can $e

!aried for satisfactory pump operation.Ca*a$!&y/ Capacity means the 3o' rate 'ith 'hichli,uid is mo!ed or pushed $y the pump to thedesired point in the process. 2t is commonlymeasured in either gallons per minute (gpm) or

cu$ic meters per hour (mhr). he capacity usuallychanges 'ith the changes in operation of theprocess. The




$a*a$!&y %e*en%s on a n,)9er of fa$&ors +!2e/

Process li,uid characteristics i.e. density& !iscosity

#ize of the pump and its inlet and outlet sections

2mpeller size

2mpeller rotational speed RPM

Pump suction and discharge temperature and pressure

conditions>or a pump 'ith a particular impeller running at a certainspeed in a li,uid& the only items on the list a$o!e thatcan change the amount 3o'ing through the pump arethe pressures at the pump inlet and outlet. he eDect on

the 3o' through a pump $y changing the outletpressures is graphed on a pump cur!e.





+s li,uids are essentially incompressi$le& the capacity isdirectly related 'ith the !elocity of 3o' in the suctionpipe.ea%/ he pressure at any point in a li,uid can $ethought of as $eing caused $y a !ertical column of the

li,uid due to its 'eight. he height of this column is calledthe static head and is e"pressed in terms of feet of li,uid. he same head term is used to measure the *ineticenergy created $y the pump. 2n other 'ords& head is ameasurement of the he height of a li,uid column that thepump could create from the *inetic energy imparted tothe li,uid. 2magine a pipe shooting a 9et of 'ater straightup into the air& the height the 'ater goes up 'ould $e thehead. he head is not e,ui!alent to pressure. Head is aterm that has units of a length and pressure has units offorce per unit area or pound per s,uare inch.




The )a!n reason for ,s!ng hea% !ns&ea% of*ress,re to measure a centrifugal pumps energyis that the pressure from a pump 'ill change if thespeci4c gra!ity ('eight) of the li,uid changes& $utthe head 'ill not change. #ince any gi!en

centrifugal pump can mo!e a lot of diDerent 3uids&'ith diDerent speci4c gra!ities& it is simpler todiscuss the pumps head and forget a$out thepressure. #o a centrifugal pump’s performance onany 8e'tonian 3uid& 'hether its hea!y (sulfuric

acid) or light (gasoline) is descri$ed $y using theterm Ihead’. he pump performance cur!es aremostly descri$ed in terms of head.




Press,re &o ea% Con3ers!on for),+a/ he statichead corresponding to any speci4c pressure is dependentupon the 'eight of the li,uid according to the follo'ingformula5

P J ρ g h

8e'tonian li,uids ha!e speci4c gra!ities typically rangingfrom .0 (light& li*e light hydrocar$ons) to 1.F (hea!y& li*econcentrated sulfuric acid). ater is a $enchmar*& ha!inga speci4c gra!ity of 1.. his formula helps in con!ertingpump gauge pressures to head for reading the pumpcur!es. he !arious head terms are discussed $elo'.




No&e5 he #u$scripts’ refers to suction conditions andId’ refers to dischargeconditions.

S&a&!$ S,$&!on ea% h+/ Head resulting from ele!ation

of the li,uid relati!e to the pump centre line. 2f the li,uidle!el is a$o!e pump centerline& h+ is positi!e. 2f the li,uidle!el is $elo' pump centerline& h+ is negati!e. 8egati!e h+ condition is commonly denoted as a Ksuction liftL conditionS&a&!$ D!s$harge ea% hd / 2t is the !ertical distance in

feet $et'een the pump centerline and the point of freedischarge or the surface of the li,uid in the discharge tan*.Fr!$&!on ea% h" / he head re,uired to o!ercome theresistance to 3o' in the pipe and 4ttings. 2t is dependentupon the size& condition and type of pipe& num$er and typeof pipe4ttings& 3o' rate& and nature of the li,uid.




Po(er an% E@$!en$yPo(er an% E@$!en$y

Bra2e orse Po(er 5,H$6/ he 'or*performed $y a pump is a function of the totalhead and the 'eight of the li,uid pumped in agi!en time period. Pump input or $ra*e

horsepo'er (BHP) is the actual horsepo'erdeli!ered to the pump shaft. Pump output orhydraulic or 'ater horsepo'er (WHP) is theli,uid horsepo'er deli!ered $y the pump.

hese t'o terms are de4ned $y the follo'ingformulas. shaft at available Power

fluid to put Power int=η

3)cos( ×××

×××=

ϕ

ρ η

I Volts

H Q g




Bes& E@$!en$y Po!n& 5,*$6/ he H& 8P#Hr&e%ciency& and BHP all !ary 'ith 3o' rate& .

Bes&E@$!en$y Po!n& 5,*$6 is the capacity at ma"imumimpeller diameter at 'hich the e%ciency is highest. +llpoints to the right or left of B@P ha!e a lo'er e%ciency.BEP as a )eas,re of o*&!),) energy

$on3ers!on/ hen sizing and selecting centrifugalpumps for a gi!en application the pump e%ciency atdesign should $e ta*en into consideration. hee%ciency of centrifugal pumps is stated as apercentage and represents a unit of measuredescri$ing the change of centrifugal force (e"pressed

as the !elocity of the 3uid) into pressure energy.




he BEP ($est e%ciency point) is the area on the cur!e'here the change of !elocity energy into pressure

energy at a gi!en gallon per minute is optimum inessence& the point 'here the pump is most e%cient.

,*$ as a )eas,re of )e$han!$a++y s&a9+eo*era&!on/ he impeller is su$9ect to non-symmetrical

forces 'hen operating to the right or left of the BEP. hese forces manifest themsel!es in manymechanically unsta$le conditions li*e !i$ration&e"cessi!e hydraulic thrust& temperature rise& anderosion and separation ca!itation. hus the operationof a centrifugal pump should not $e outside the

furthest left or right e%ciency cur!es pu$lished $y themanufacturer.




Performance in these areas induces premature $earing andmechanical seal failures due to shaft de3ection& and anincrease in temperature of the process 3uid in the pump

casing causing seizure of close tolerance parts andca!itation.

,*$ as an !)*or&an& *ara)e&er !n $a+$,+a&!ons/ BEP isan important parameter in that many parametriccalculations such as speci4c speed& suction speci4c speed&hydrodynamic size& !iscosity correction& head rise toshutoD& etc. are $ased on capacity at BEP. Many usersprefer that pumps operate 'ithin F< to 11< of BEP foroptimum performance. +P2 E1 speci4es that pumps shallha!e a preferred operating region of N-1/< of $este%ciency capacity of the furnished impeller. Rated capacity

shall $e 'ithin the region of F-11< of $est e%ciencycapacity of the furnished impeller.




Re+a&!onsh!* 9e&(een 'o( an% 3!9ra&!on

S ! S % S !S*e$!$ S*ee% S*e$!$




S*e$!$ S*ee% S*e$!$S*e$!$ S*ee% S*e$!$s*ee% Ca+$,+a&!ons*ee% Ca+$,+a&!on

S*e$!$ S*ee% / #peci4c speed as a measure of thegeometric similarity of pumps #peci4c speed (8s) is anon-dimensional design inde" that identi4es thegeometric similarity of pumps. 2t is used to classifypump impellers as to their type and proportions.

Pumps of the same 8s $ut of diDerent size areconsidered to $e geometrically similar& one pump$eing a size- factor of the other.S*e$!$ s*ee% Ca+$,+a&!on he follo'ing formula is used to determine speci4c

speed5where: N is the rotational speed in rpmQ is the fow at BEP in m3 /hr H is the head at Q in m N0.

0.

H

QNN

s

⋅

=




#peci4c speed as a measure of the shape or class ofthe impellers




S*e$!$ s*ee% as a )eas,re of &he sha*e orS*e$!$ s*ee% as a )eas,re of &he sha*e or$+ass of &he !)*e++ers$+ass of &he !)*e++ers

he speci4c speed determines the general shape orclass of the impellers. +s the speci4c speed increases&the ratio of the impeller outlet diameter& 6/& to theinlet or eye diameter& 61& decreases. his ratio$ecomes 1. for a true a"ial 3o' impeller.

Radial 3o' impellers de!elop head principally throughcentrifugal force. Radial impellers are generally lo'3o' high head designs. Pumps of higher speci4cspeeds de!elop head partly $y centrifugal force andpartly $y a"ial force. + higher speci4c speed indicatesa pump design 'ith head generation more $y a"ial

forces and less $y centrifugal forces. +n a"ial 3o' orpropeller pump 'ith a speci4c speed of 1& orgreater generates its head e"clusi!ely through a"ialforces.




+"ial 3o' impellers are high 3o' lo' head designs.#peci4c speed identi4es the appro"imate accepta$leratio of the impeller eye diameter (D1) to the impellerma"imum diameter (D2) in designing a good impeller.

8s5 0 to 0 D1D2 O 1.0 - radial 3o' pump8s5 0 to 1 D1D2 1.0 - mi"ed 3o' pump

8s5 1 to 10 D1D2 J 1 - a"ial 3o' pump

#peci4c speed is also used in designing a ne' pump$y size- factoring a smaller pump of the same speci4c

speed. he performance and construction of thesmaller pump are used to predict the performanceand model the construction of the ne' pump.




S,$&!on s*e$!$ s*ee% 5Nss6S,$&!on s*e$!$ s*ee% 5Nss6

#uction speci4c speed (8ss) is adimensionless num$er or inde" thatde4nes the suction characteristics of a

pump. 2t is calculated from the sameformula as 8s $y su$stituting H $y8P#Hr. 2n multi-stage pump the 8P#Hr

is $ased on the 4rst stage impeller.




S*e$!$ s*ee% as a )eas,re of &he safeS*e$!$ s*ee% as a )eas,re of &he safeo*era&!ng rangeo*era&!ng range

8s are commonly used as a $asis for estimating thesafe operating range of capacity for a pump. hehigher the 8ss is& the narro'er is its safe operatingrange from its BEP. he num$ers range $et'een

& and /&. Most users prefer that theirpumps ha!e 8ss in the range of F to 11 foroptimum and trou$le- free operation.



Than2

Yo, for

A&&en&!on

Date post:	18-Feb-2018
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2 Centrifugal Pumps ROTODYNAMIC Two

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