SIST-TP CEN/TR 13930:2009

SLOVENSKI STANDARD
SIST-TP CEN/TR 13930:2009
01-april-2009
1DGRPHãþD
SIST CR 13930:2001
&HQWULIXJDOQHþUSDONH1DþUWRYDQMHGRYRGRY3ULSRURþLOD]DYJUDGQMRþUSDON
Rotodynamic pumps - Design of pump intakes - Recommendations for installation of
pumps
Kreiselpumpen - Gestaltung der Einlaufbauten - Empfehlungen zur Installation der
Pumpen
Pompes rotodynamiques - Conception des ouvrages d'aspiration - Recommandations
d'installation des pompes
Ta slovenski standard je istoveten z: CEN/TR 13930:2009
ICS:
23.080 ýUSDONH Pumps
SIST-TP CEN/TR 13930:2009 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 13930:2009

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SIST-TP CEN/TR 13930:2009
TECHNICAL REPORT
CEN/TR 13930
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
January 2009
ICS 23.080 Supersedes CR 13930:2000
English Version
Rotodynamic pumps - Design of pump intakes -
Recommendations for installation of pumps
Pompes rotodynamiques - Conception des ouvrages Kreiselpumpen - Gestaltung der Einlaufbauten -
d'aspiration - Recommandations d'installation des pompes Empfehlungen zur Installation der Pumpen
This Technical Report was approved by CEN on 13 October 2008. It has been drawn up by the Technical Committee CEN/TC 197.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 13930:2009: E
worldwide for CEN national Members.

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Contents Page
Foreword . 3
Introduction . 4
1 Scope . 5
2 General . 5
2.1 Factors which influence the operation of the plant . 5
2.2 General design principles for a pumping plant . 6
3 Plant with vertical suction inlet . 7
3.1 General arrangements . 7
3.2 Diameter (D) at the entrance of the bellmouth or the tapered suction. 9
3.3 Distance (C) between the bellmouth or the tapered suction inlet and floor . 10
3.4 Distances between suction inlet axis and walls . 11
3.4.1 Distance (L) between suction inlet axis and side walls . 11
3.4.2 Distance (E) between suction inlet axis and rear wall . 11
3.5 Submergence (S) . 11
3.5.1 Conditions to be satisfied for the determination of submergence . 11
3.5.2 Determination of submergence (S) . 12
3.6 Strainer . 12
3.7 Feed intake - Pump environment . 13
3.7.1 Feed intake . 13
3.7.2 Immediate environment of the pump . 20
3
3.8 Case of pumping plant with vertical suction inlet and flow rate less than 50 m /h . 23
4 Plant with intake with top suction inlet . 23
5 Plant with intake with floor suction inlet . 24
5.1 Bellmouth . 25
5.2 Submergence of horizontal plate . 25
5.3 Special anti-vortex devices . 25
6 Plant with intake with wall suction inlet . 25
6.1 Shape and position of suction inlet . 25
6.2 Submergence . 27
6.3 Special anti-vortex devices . 27
Bibliography . 29

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Foreword
This document (CEN/TR 13930:2009) has been prepared by Technical Committee CEN/TC 197 “Pumps”, the
secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes CR 13930:2000.
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Introduction
In addition to the risks of cavitation that may exist at the intake of any pump depending on the NPSH available,
pumping from a sump poses specific problems.
In fact, if the water passes from a flow state with an exposed surface to flow under pressure, significant swirling
movements may occur and sometimes be amplified, thus creating a sort of funnel or vortex which opens out into
the exposed surface of the sump with a risk of air being entrained or creating a swirling chimney, or whirl between
the bottom and the intake producing degassing or vaporisation of the liquid in the entrance of the pump (see
Figures 1a) and 1b) below).
These phenomena, which are generally unsteady, can have unwanted effects on the plant:
 undesirable vibration of various pump components;
 increased risk of cavitation;
 drop in efficiency;
 reduction in flow rate and/or head;
 risk of floating bodies being sucked in;
 intense and irregular noise.
Compliance with the recommendations in this document makes it possible, in most commonly encountered
industrial applications, to avoid or at least limit the phenomena mentioned above.

1a) Vortex causing entrainment of air in suction piping 1b) Chimney or whirl between the floor and the
suction inlet
Figure 1 — Types of possible disturbances
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1 Scope
1.1 This technical Report contains recommendations for the design of pump intakes and the installation of
pumps.
As far as possible, these recommendations should be adhered to in order to obtain correct operation of the plant.
These recommendations are applicable regardless of the flow rate of the plant:
 plant which works with clear water (or relatively unclouded) and relatively non-aerated water or any other liquid
having physical and chemical properties which are similar to those of water;
NOTE This document nevertheless contains several general recommendations for operation with cloudy (or very cloudy)
water.
 pumping plant which has its own floor.
1.2 This document deals with various intake configurations:
 Clause 3 contains recommendations which apply to intakes with vertical suction inlet;
 Clause 4 contains recommendations applicable to intakes with top suction inlet;
 Clause 5 contains recommendations applicable to intakes with floor suction inlet;
 Clause 6 contains recommendations applicable to intakes with side-wall suction inlet.
2 General
2.1 Factors which influence the operation of the plant
The following factors have an effect on the operation of the plant:
a) Characteristics and position of the suction inlet:
 arrangements of the suction inlet (vertical with bellmouth or tapered suction, top, floor or side-wall
intake);
 presence or absence of a bellmouth or tapered suction;
 distance between suction inlet and floor;
 distance between suction inlet and side-walls;
 submergence (level of liquid relative to suction inlet);
 strainer.
b) Inflow of liquid to the intake:
 inflow velocity of the liquid;
 shapes and dimensions of inflow;
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 position of inflow.
c) Environment of the pump in the plant:
 velocity of liquid close to the pump;
 shapes and dimensions of the plant;
 special devices (gratings), anti-vortex device;
 relative positions of pumps to each other and in the plant.
Clauses 3 to 6 below contain recommendations concerning the determining factors for each arrangement of the
suction inlet.
NOTE If the liquid is charged with solid particles in suspension, the following recommendations may be amended. Prevent
the velocity of the fluid falling below a value which allows the deposition of solid materials. A minimum value of 0,7 m/s close to
the suction inlet is currently admitted.
2.2 General design principles for a pumping plant
In order for the pump to be fed under the best possible conditions, effort should be made to obtain a permanent,
uniform and even flow in the suction pipe. To achieve this, it is necessary to:
 supply the suction pipe for each pump with a balanced flow which is free from swirl;
 ensure that the water accelerates gradually along the intake; any deceleration generates flow instabilities;
 avoid any entrainment of air by suction (vortex) or by churning (weir).
Ensure that these conditions are adhered to as closely as possible regardless of the operating conditions of the
plant (one or more pump(s) working, one or more intake sluice(s) or filter(s) in service, high water level or low water
level, etc.).
The stipulations in the following clauses are aimed at achieving this. In those, inevitably numerous, situations that
are not dealt with in this document, the plant designer should adopt the following principles:
a) in water inflows intakes, stay within moderate velocities which allow gradual acceleration: examples of such
velocities are those of the order of 0,3 m/s in the approach channel, 0,5 m/s in the strainer, 1,5 m/s in the
bellmouth or tapered suction, and 4 m/s in the suction pipe;
b) avoid excessively large chambers and dead zones which generate overall swirl in the flow and vortices as well
as the deposition of solids if the water contains substances in suspension;
c) prevent separation by avoiding sudden widening and excessively divergent angles by preferring shaped forms
for pillars, low walls, bellmouth or tapered suction, etc;
d) avoid sudden changes in direction caused, for instance, by lateral feed and excessively sloping falls;
e) eliminate any obstacle which might interfere with flow over a sufficient distance (of the order of 10 times the
diameter D at the entrance to the bellmouth or tapered suction) before the suction pipe;
f) avoid any asymmetry in the mode of operation as well as in the design of structures;
g) at the entrance to the suction pipe, ensure an adequate submergence for the minimum working level and
increase the submergence recommended below in this standard significantly if flow conditions are mediocre;
h) if a chamber is fed with water by an overflow, ensure that the later does not entrain air and provide a baffle
device.
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It is far preferable to design a plant which is intrinsically problem-free from the outset rather than to rely on baffles
or anti-vortex accessories which are often only a palliative offering efficiency which is difficult to predict.
In difficult cases and if the importance of the plant justifies it, it is recommended to use a reduced model to check
whether there is any need to improve the arrangements made.
3 Plant with vertical suction inlet
3.1 General arrangements
In these configurations the presence of a bellmouth is necessary but alternatively, the bellmouth may be replaced
by a tapered suction.
Installations with a vertical suction are shown diagrammatically in Figures 2 and 3.
a) The pump design may be:
 axial flow without exceeding the outside diameter of the bellmouth or tapered suction greatest
diameter;
 centrifugal or mixed flow with bellmouth possibly wider than diameter of the bellmouth or tapered
suction greatest diameter.
b) The position of the pump on the piping can be:
 horizontal or vertical;
 immersed or not immersed.


Figure 2 — Vertical suction inlet with bellmouth - Normal configuration

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a a a
) ) )
3a) Centrifugal impeller 3b) Mixed-flow impeller 3c) Axial flow impeller
a) The number of stages is stated for a) The number of stages is stated for a) The number of stages is stated for
information only information only information only

3d) Non-immersed horizontal pump 3e) Non immersed vertical pump 3f) Non immersed vertical pump

3g) Immersed vertical pump
Figure 3 — Vertical suction inlet with bellmouth (or with tapered suction) -
Example of possible configurations
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3.2 Diameter (D) at the entrance of the bellmouth or the tapered suction
Figure 4 shows typical profile of bellmouth.

Figure 4 — Bellmouth
The diameter D at the entrance to the bellmouth is a result of the bellmouth profile, which is generally a quarter
ellipse of which the short and long axes have the values 2a and 2b respectively.
If D is the diameter of the piping at the entrance to the impeller of the pump, the value of D is generally between
o
1,4 D and 1,8 D inclusive, the most common values are between 1,5 D and 1,6 D inclusive.
o o o o
It is this value which is used as a reference for the recommendations given in sub-clause 3.3 and so on.
As an alternative of a suction by bellmouth, Figure 5 illustrates typical profile of tapered suction.

Figure 5 — Alternative with tapered suction
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