Technical specifications for centrifugal pumps - Class I (ISO 9905:1994)

Consist of a basic text covering general requirements. The technical requirements refer only to the pump unit. Includes design features concerned with installation, maintenance and safety of such pumps, including baseplate, coupling and auxiliary piping. The selection of the class to be used is made in accordance with the technical requirements for the application for which the pump is intended. The class chosen is to be agreed between purchaser and manufacturer/supplier.

Kreiselpumpen technische Anforderungen - Klasse I (ISO 9905:1994)

Diese Internationale Norm gilt für die Anforderungen der Klasse I (höchste Anforderung) für Kreiselpumpen, die in verschiedenen Industrien eingesetzt werden. Sie umfaßt einen Grundtext, der die allgemeinen Anforderungen festlegt. Die technischen Anforderungen gelten nur für das Pumpenaggregat. Speicherpumpen sind in dieser Internationalen Norm nicht erfaßt. Hierfür wird eine separate Norm von IEC herausgegeben.

Spécifications techniques pour pompes centrifuges - Classe I (ISO 9905:1994)

La CEI 60633:1998+A1:2009 s'applique au transport d'énergie en courant continu à haute tension (CCHT) et spécialement aux sous-stations de conversion de CCHT dans lesquelles des convertisseurs électroniques de puissance sont utilisés pour la conversion du courant alternatif en courant continu ou vice versa.
Cette version consolidée comprend la seconde édition (1998) et son amendement 1 (2009). Il n'est donc pas nécessaire de commander les amendements avec cette publication.

Technical specifications for centrifugal pumps - Class I (ISO 9905:1994)

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SIST EN ISO 9905:2000
Technical specifications for centrifugal pumps - Class I (ISO 9905:1994)
Technical specifications for centrifugal pumps - Class I (ISO 9905:1994)
Kreiselpumpen technische Anforderungen - Klasse I (ISO 9905:1994)
Spécifications techniques pour pompes centrifuges - Classe I (ISO 9905:1994)
Ta slovenski standard je istoveten z: EN ISO 9905:1997
23.080 ýUSDONH Pumps
SIST EN ISO 9905:2000 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 9905:2000
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SIST EN ISO 9905:2000
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SIST EN ISO 9905:2000
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SIST EN ISO 9905:2000
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SIST EN ISO 9905:2000
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SIST EN ISO 9905:2000
First edition
Technical specifications for centrifugal
- Class I
Spbcifications techniques pour pompes centrifuges - Classe I
Reference number
IS0 9905:1994(E)
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SIST EN ISO 9905:2000
IS0 9905: 1994(E)

1 Scope ..............................................................................................

2 Normative references .....................................................................

3 Definitions .......................................................................................

4 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

....................................................... 26
6 Shop inspection and tests
.......................................................... 29
7 Preparation for dispatch

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8 Responsibilities

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

A Centrifugal pump - Data sheet
. . . . . . . . . . . . . . . . . . . . . . . . . . . 36
B External forces and moments on branches

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C Enquiry, proposal, purchase order
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D Documentation after purchase order
. . . . . . . . . . ..e.................................................... 46
E Peak displacement
F Examples of seal arrangements
............................................... 49
G Piping arrangements for seals
........................... 67
H Code for identification of fluid connections
J Materials and material specifications for centrifugal pump parts

K Check-list ................................................................................

L Bibliography
0 IS0 1994

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced

or utilized in any form or by any means, electronic or mechanical, including photocopying and

microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
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SIST EN ISO 9905:2000
0 IS0
IS0 9905: 1994(E)
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 9905 was prepared by Technical Committee
lSO/TC 115, Pumps, Subcommittee SC 1, Dimensions and technical
specifications of pumps.
Annexes A, B, C and D form an integral part of this International Standard.
Annexes E, F, G, H, J, K and L are for information only.
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SIST EN ISO 9905:2000
63 IS0
IS0 9905: 1994(E)
This International Standard is the second of a set dealing with technical
specifications of centrifugal pumps; the specifications are designated as
Classes I, II and III. Class I (this International Standard) comprises the most
severe and Class III (see IS0 9908) the least severe requirements. For
requirements for Class II centrifugal pumps, see IS0 5199.
The selection of the class to be used is made in accordance with the
technical requirements for the application for which the pump is intended.
The class chosen is to be agreed between purchaser and
The safety requirements of the field of application are furthermore to be
taken into account.
However, it is not possible to standardize the class of technical require-
ments for centrifugal pumps for a certain field of application, because each
field of application comprises different requirements. All classes (I, II and
III) can be used in accordance with the different requirements of the pump
application, e.g. for an oil refinery plant, chemical plant or power plant. It
may happen that pumps built in accordance with classes I, II and III may
work beside each other in one plant.
Conditions covering specific applications or industrial requirements are
dealt with in separate standards.
Criteria for the selection of a pump of the class required for a certain ap-
plication may be based on:
- reliability,
- operating conditions,
- environmental conditions,
- local ambient conditions.
Throughout this International Standard, text written in bold letters indi-
cates where a decision may be required by purchaser, or where agree-
ment is required between purchaser and manufacturer/supplier.
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SIST EN ISO 9905:2000
IS0 9905: 1994(E)
Technical specifications for centrifugal pumps -
Class I
based on this International Standard are encouraged
1 Scope
to investigate the possibility of applying the most re-
cent editions of the standards indicated below.
1.1 This International Standard covers the Class I
Members of IEC and IS0 maintain registers of cur-
(most severe) requirements for centrifugal pumps
rently valid International Standards.
used in various industries. It consists of a basic text
covering general requirements. The technical require-
I SO 7-l : 1982, Pipe threads where pressure-tight
ments refer only to the pump unit.
joints are made on the threads - Part 1: Designation,
dimensions and tolerances.
Storage pumps are not included in this International
Standard. A separate standard will be issued by IEC.
IS0 76: 1987, Rolling bearings - Static load ratings.

1.2 This International Standard includes design fea- IS0 185: 1988, Grey cast iron - Classification.

tures concerned with installation, maintenance and
IS0 228-l : 1982, Pipe threads where pressure-tight
safety of such pumps, including baseplate, coupling
joints are not made on the threads - Part 1: Desig-
and auxiliary piping.
nation, dimensions and tolerances.
1.3 Where this International Standard specification
IS0 281 :I 990, Rolling bearings - Dynamic load
has been called for:
ratings and rating life.
a) and requires a specific design feature, alternative
IS0 427:1983, Wrought copper-tin alloys - Chemical
designs may be offered which meet the intent of
composition and forms of wrought products.
this International Standard, provided that the al-
ternative is described in detail;
IS0 544: 1989, Filler materials for manual welding -
Size requirements.
b) pumps not complying with all requirements of this
International Standard may be offered for con-
IS0 1940-l : 1986, Mechanical vibration - Balance
sideration, provided that all deviations are stated.
quality requirements of rigid rotors - Part 1: Deter-
mina tion of permissible residual unbalance.
IS0 2372: 1974, Mechanical vibration of machines
with operating speeds from 10 to 200 rev/s - Basis
for specifying evaluation standards.
2 Normative references
IS0 2548:1973, Centrifugal, mixed flow and axial
The following standards contain provisions which,
- Code for acceptance tests - Class C (It is
through reference in this text, constitute provisions
planned to combine IS0 2548 with IS0 3555 during
of this International Standard. At the time of publica-
their next revision to create a new lntema tional Stan-
tion, the editions indicated were valid. All standards
are subject to revision, and parties to agreements
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SIST EN ISO 9905:2000
0 IS0
IS0 9905: 1994(E)
3.3 operating conditions: All operating parameters
IS0 2858: 1975, End-suction centrifugal pumps (rating
(for example temperature, pressure) determined by a
16 bar) - Designation, nominal duty point and di-
given application and pumped liquid.
These parameters will influence the type of con-
IS0 3069: 1974, End suction centrifugal pumps - Di-
struction materials.
mensions of cavities for mechanical seals and for soft
3.4 allowable operating range: Flow range, de-

IS0 3274:1975, Instruments for the measurement of fined by the manufacturer/supplier, at the specified

surface roughness by the profile method - Contact operating conditions using the impeller supplied, as

(stylus) instruments of consecutive profile transfor- limited by cavitation, heating, vibration, noise, shaft

ma tion deflection and other similar criteria; range whose up-
- Contact profile meters, system M.
per and lower limits are denoted by maximum and
IS0 3506: 1979, Corrosion-resistant stainless steel
minimum continuous flow, respectively.
fasteners - Specifications.
3.5 maximum allowable casing working
IS0 3555:1977, Centrifugal, mixed flow and axial
pressure: Greatest outlet pressure at the specified
- Code for acceptance tests - Class B (It is
operating temperature for which the pump casing is
planned to combine IS0 3555 with IS0 2548 during
their next revision to create a new lnterna tional Stan-
3.6 basic design pressure: Pressure derived from
the permitted stress at 20 “C of the material used for
IS0 374411981, Acoustics - Determination of sound
the pressure-containing parts.
power levels of noise sources - Engineering meth-
ods for free-field conditions over a reflecting plane.
3.7 maximum outlet working pressure: Sum of
the maximum inlet pressure plus maximum differen-
IS0 374611979, Acoustics - Determination of sound
tial pressure at rated conditions using the supplied
power levels of noise sources - Survey method.
IS0 3755:1991, Cast carbon steels for general engin-
3.8 rated outlet pressure: Outlet pressure of the
eering purposes.
pump at the guarantee point with rated flow, rated
speed, rated inlet pressure and density.
IS0 4863:1984, Resilient shaft couplings - Infor-
mation to be supplied by users and manufacturers.
3.9 maximum inlet pressure: Highest inlet press-
IS0 7005-I :I 992, Metallic flanges - Part 1: Steel
ure to which the pump is subjected during operation.
Inlet pressure for the
3.10 rated inlet pressure:
IS0 7005-2: 1988, Metallic flanges - Part 2: Cast iron
e point.
opera ting conditions at the gu arante
3.11 maximum allowable temperature: Highest
IS0 7005-3:1988, Metallic flanges - Part 3: Copper
allowable continuous temperature for which the
alloy and composite flanges.
equipment (or any part to which the term refers) is
suitab e when handling the specified operating fluid
specified operating pressure.
at the
3 Definitions
3.12 rated power input: Power required by the
at the rated conditions.
For the purposes of this International Standard, the
following definitions apply.
3.13 maximum dynamic sealing pressure: High-
est pressure expected at the shaft seals during any
31 . normal conditions: Conditions at which usua
specified operating condition and during startup and
operation is expected.
3.2 rated conditions: Specified guarantee-point op
NOTE 1 Pn determining this pressure, consideration
erating conditions, including flowrate, head, power,
should be given to the maximum inlet pressure, circulation
efficiency, net positive suction head, suction press-
or injection (flush) pressure and the effect of internal clear-
ure, temperature, density, viscosity and speed. ance changes.
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SIST EN ISO 9905:2000
IS0 9905: 1994(E)
3.14 minimum permitted flow
is rotated manually in its bearings in the horizontal
(1) for stable flow: Lowest flowrate at which the
The radial face is that which determines the alignment
pump can operate without exceeding the noise and
of a seal component.
vibration limits imposed by this International Standard.
(2) for thermal flow: Lowest flowrate at which the
3.24 shaft deflection: Displacement of a shaft from
pump can operate and still maintain the temperature
its geometric centre in response to the radial hydraulic
of the pumped liquid below that at which net positive
forces acting on the impeller.
ing caused by impeller unbalance or shaft runout.
3.15 corrosion allowance: That portion of the wall
thickness of the parts wetted by the pumped liquid in
3.25 circulation (flush): Return of pumped liquid
excess of the theoretical thickness required to with-
from a high pressure area to seal cavity, by external
stand the pressure limits given in and
piping or internal passage, to remove heat generated
at the seal or to maintain positive pressure in the seal
3.16 maximum allowable continuous speed:
cavity or treated to improve the working environment
Highest speed at which the manufacturer will permit
for the seal.
continuous operation.
NOTE 4 In some cases it may be desirable to circulate
from the seal cavity to a lower pressure area (for example,
3.17 rated speed: Number of revolutions of the
the inlet).
pump per unit time required to meet the rated con-
3.26 injection (flush): Introduction of an appropriate
NOTE 2 Induction motors will operate at a speed that is
(clean, compatible, etc.) liquid into the seal cavity from
a function of the load imposed.
an external source and then into the pumped liquid.
3.18 trip speed: Speed at which the independent
3.27 quenching: Continuous or intermittent intro-
emergency overspeed device operates to shut down
duction of an appropriate (clean, compatible, etc.) fluid
a prime mover.
on the atmospheric side of the main shaft seal to ex-
clude air or moisture, to prevent or clear deposits (in-

3.19 first critical speed: Speed of rotation at which cluding ice), lubricate an auxiliary seal, snuff out fire,

the lowest lateral natural frequency of vibration of the dilute, heat or cool leakage.

rotating parts corresponds to the frequency of ro-
3.28 barrier liquid (buffer): An appropriate (clean,
compatible, etc.) liquid inserted between two seals
(mechanical seal and/or soft packing).
3.20 design radial load: Maximum hydraulic radial
forces on the largest impeller (diameter and width)
NOTE 5 The barrier liquid pressure depends on the seal
operating within the manufacturer’s specified range
arrangement. The barrier liquid may be used to prevent air
on its maximum speed curve using the design liquid
entering the pump. The barrier liquid is normally easier to
(normally 1 000 kg/m3).
seal than the pumped liquid and/or creates less hazard if
leakage occurs.
3.21 maximum radial load: Maximum hydraulic ra-
dial forces on the largest impeller (diameter and
3.29 throttle bush (safety bush): Close-clearance
width) operating at any point on its maximum speed
restrictive bush around the shaft (or sleeve) at the
curve with a maximum liquid density.
outboard end of a mechanical seal to reduce leakage
in case of seal failure.
3.22 shaft runout: Total radial deviation indicated
by a device measuring shaft position in relation to the
3.30 throat bush: Close-clearance restrictive bush
bearing housing as the shaft is rotated manually in its
around the shaft (or sleeve) between the seal (or
bearings with the shaft in the horizontal position.
packing) and the impeller.

3.23 face runout: Total axial deviation indicated at 3.31 pressure casing: Composite of all stationary

the outer radial face of the stuffing box by a device pressure-containing parts of the unit, including all

attached to and rotated with the shaft when the shaft branches and other attached parts.

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SIST EN ISO 9905:2000
@I3 IS0
IS0 9905: 1994(E)

3.32 double casing: Type of construction in which 3.42 suction specific speed: Parameter relating the

rotational speed, the flowrate and the NPSHR, deter-
the pressure casing is separate and distinct from the
mined at the best efficiency point.
pumping elements contained in it.
3.33 barrel casing: Refers specifically to a pump of
3.43 hydrodynamic bearing: Bearing whose sur-
the double casing type.
face is oriented to another surface such that relative
motion forms an oil wedge to support the load with-
3.34 vertical canned pump: Vertical pump inserted
out metal-to-metal contact.
in an outer casing (can or caisson) taking its suction
from the liquid in the annular space.
3.44 hydrodynamic radial bearing: Bearing of
sleeve-journal or tilting-shoe type construction.
3.35 vertical canned motor pump: Glandless
pumping set in which the stator of the (electric) motor
3.45 hydrodynamic thrust bearing: Bearing of
is sealed by a can against the rotor which runs in the
multiple-segment or tilting-shoe type construction.
pumped liquid or in any other liquid.
3.46 design values: Values used in the design of a
3.36 hydraulic power recovery turbine: Pump op-
pump for the purpose of determining the perform-
erated with reversed flow to deliver mechanical en-
ance, the minimum permissible wall thickness and
ergy at the coupling obtained from the recovery of
physical characteristics of the different parts of the
energy released by the reduction of fluid pressure
(and sometimes from the additional energy released
by vapour or gas evolution from the fluid).
NOTE 8 Use of the word design in any term (such as
design pressure, design power, design temperature or de-
NOTE 6 For hydraulic power recovery turbine branches,
sign speed) should be avoided in the purchaser’s specifi-
all references in this standard to suction and discharge apply
cations. This terminology should be used only by the
to the outlet and inlet, respectively.
equipment designer and manufacturer/supplier.
3.37 radial split: Refers to casing joints that are
3.47 coupling service factor: A factor k, by which
transverse to the shaft centreline.
is multiplied the nominal torque IQ,, of the driver in or-
der to obtain the rated torque TK = k7’,,,, which makes
3.38 axial split: Refers to casing joints that are par-
due allowance for cycle torque fluctuations from the
allel to the shaft centreline.
pump and/or its driver, and therefore ensures satis-
factory coupling life.
3.39 net positive suction head (NPSH): Absolute
total inlet head above the head equivalent to the va-
pour pressure referred to the NPSH datum plane.
4 Design
NOTE 7 NPSH is referred to the datum plane, whereas
inlet total head is referred to the reference plane. The NPSH
4.1 General
datum plane is the horizontal plane through the centre of
the circle described by the external points of the entrance

edges of the impeller blades; in the case of double inlet Whenever the documents include contradicting tech-

pumps with vertical or inclined axis, it is the plane through
nical requirements, they shall apply in the following
the higher centre. The manufacturer/supplier should indicate
the position of this plane with respect to precise reference
points on the pump.
iry, if no order is placed)
pure hase order (or enqu
(see annexes C and D 1;
head available
3.40 net positive suction
(NPSHA): NPSH determined by the conditions of the
b) data sheet (see annex A);
installation for a specified liquid, temperature and rate
of flow.
c) this International Standard;
3.41 net positive suction head required
d) other standards to which reference is made in the
(NPSHR): Minimum NPSH for a pump achieving a
order (or enquiry, if no order is placed).
specified performance at the specified rate of flow
The applicability of any national and local codes,
and speed (occurrence of visible cavitation, increase
regulations, ordinances or rules shall be mutually
of noise due to cavitation, appearance of head or ef-
agreed upon by the purchaser and the manu-
ficiency drop, head or efficiency drop of a given
amount, etc.).
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SIST EN ISO 9905:2000
0 IS0
IS0 9905: 1994(E)
4.1 .l Characteristic curve in performance curves is the NPSH corresponding to
a drop of 3 % of the total head of the first stage of the The characteristic curve for the supplied
pump (NPSH3).
impeller shall show the head, efficiency, NPSHR and
Should the pump manufacturer/supplier consider that,
the power input, plotted against flowrate. It shall also
because of the construction material and liquid
show the allowable operating range of the pump.
pumped, a greater NPSH is required, this should be
Headlflowrate curves (on the basis of calculation or
stated in the proposal and the appropriate curve pro-
test) for the largest and smallest impeller diameters
shall be plotted for single stage pumps, and for
multistage pumps when requested.
The manufacturer/supplier shall specify on the data
sheet the net positive suction head required (NPSHR) Pumps that have stable headlflowrate
when the pump is operated with water at the rated
curves which continuously rise to shutoff are pre-
flowrate and rated speed.
ferred for most applications and are required when
parallel operation is specified by the purchaser. Un-
Hydrocarbon reduction or correction shall not be ap-
stable headlflowrate curves or curves with dips (such
as propeller pump curves) can be offered providing
the application is suitable and the curve shape devi-
For NPSH tests, see 6.3.5.
ations are shown. When service conditions are such
that a stable curve is technically impossible, other
4.1.3 Pump design
means of ensuring the desired flow(s) must be used.
When parallel operation is specified, the rise of the Pumping units may be of single-stage or
head at rated flowrate shall have sufficient slope to
multistage design. When the rated inlet gauge press-
avoid instability of flow.
ure is positive or the differential pressure is more than
3,5 bar, the pump should be designed to minimize the The best efficiency point for the supplied
pressure on the shaft seals unless thrust balance re-
impeller should preferably be between the rated point
quirements dictate otherwise. On single-stage over-
and the normal point (see 3.1).
hang designs this can be accomplished with rings or
pumping vanes on the back of the impeller. On When the pump design permits a constant-
multistage pumps this can be accomplished either by
speed driver, the pump shall be capable of approxi-
a back-to-back impeller arrangement combined with
mately a 5 % head increase at rated conditions by
a close clearance throttle bush, or by an in-line
installing a new larger impeller or impellers.
impeller arrangement using balance drums or discs. Pumps that handle Newtonian liquids
Other means can be used after agreement be-
more viscous than water shall have their per-
tween purchaser and manufacturer/supplier.
formance corrected in accordance with the con-
version factors to be agreed between purchaser

and manufacturer/supplier. Non-Newtonian liq- High-energy pumps (head greater than

uids require special consideration. 200 m per stage and power more than 225 kW per

stage) require special consideration to ensure that the

4.1.2 Net positive suction head (NPSH) radial distance between the volute tongue (including

double volute casing) or diffuser vane and the impeller
NPSHR shall be based on cold water according to
periphery is so dimensioned to avoid undue vibrations
IS0 2548 and/or IS0 3555’9 unless otherwise
and noise (blade-passing frequency and low frequency
at reduced flowrates).
The NPSHR curve as a function of flow for water shall Vertical pumps with threaded line shaft
be provided.
coupling that could be damaged by reverse rotation
shall be provided with a non-reverse ratchet or other
NPSHA must exceed NPSHR by a 10 % margin but in
each case by not less than 0,5 m. The basis for use approved means.

I) A combination of IS0 2548 and IS0 3555 and their simultaneous revision in a new International Standard is foreseen.

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SIST EN ISO 9905:2000
0 IS0
IS0 9905: 1994(E)
circulation flow for the mechanica I sea I (especially All equipment shall be designed to permit d

rapid and economical maintenance. Major parts such for pumps with low rate of flow);

as casing components and bearing housings shall be
e) properties of the pumped medium (viscosity, sol-
designed (shouldered or dowelled) to ensure accurate
ids content, density);
alignment on reassembly.
f) power loss and slip through the transmission; Control of the sound level of all equipment
supplied shall be a joint effort of the purchaser and
g) atmospheric conditions at the pump site.
the manufacturer/supplier. Unless otherwise speci-
fied, the equipment supplied by the manufac-
Drivers for any pumps covered by this International
turer/supplier shall conform to the requirements of
Standard shall have power output ratings at least
local regulations and to the maximum allowable sound
equal to the percentage of rated pump power input
level specified by the purchaser.
given in figure I but not less than 1 kW. Where it ap-
pears that this will lead to unnecessary oversizing of
NOTE 9 The scope of this International Standard ex-
the driver, an alternative proposal shall be submitted
cludes the driver, but a contribution of the driver to the
for the purchaser’s approval.
sound level should be taken into account. Thrust load
When the thrust bearing is not part of the pump, and
4.1.4 Outdoor installation
unless otherwise approved by the purchaser, motor,
turbine or gear drivers for vertical pumps, including
The purchaser shall specify whether the installation is
‘in-line vertical pumps, shall be designed to carry the
indoors (heated or unheated) or outdoors (with or
maximum thrust the pump may develop while start-
without a roof) and the local ambient conditions in

which the equipment must operate (including maxi- ing, stopping or operating at any flowrate. The maxi-

mum and *minimum temperatures, unusual humidity, mum thrust load shall be determined at double the

corrosive air or dust problems). The unit and its initial internal clearances. If the driver is not supplied

by the manufacturer/supplier he shall notify the pur-
auxiliaries shall be suitable for operation in these
chaser of such requirements.
specified conditions. For the purchaser’s guidance,
the manufacturer/supplier shall list in the proposal any
special protection that the purchaser is required to
4.2.2 Turbine-driven pumps Steam turbines
The steam turbines selected shall be capable of car-
4.2 Drivers
rying the pump rated power input required for the
rated conditions based on the guaranteed pump ef-
4.2.1 General
ficiency, or alternatively the maximum power input
required for the full operating range of the pump. The
4.2.1 .I Requirements for determining rated drive
steam turbine power rating shall be based on the
minimum inlet and maximum exhaust steam con-
ditions specified.
The following shall be considered when determining
the rated performance of the drive: Turbine-driven pump speed
a) application and method of operation of the pump.
The turbine-driven pumps shall be designed to oper-
For instance in the case of parallel operation, the
ate continuously at 105 % of rated speed and to op-
possible performance range with only one pump
erate briefly, under emergency conditions, at up to
in operation, taking int

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