ISO 14694:2003

INTERNATIONAL ISO
STANDARD 14694
First edition
2003-03-15
Industrial fans — Specifications for
balance quality and vibration levels
Ventilateurs industriels — Spécifications pour l'équilibrage et les
niveaux de vibration
Reference number
©
ISO 2003
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ii © ISO 2003 — All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 2
3 Terms and definitions. 2
4 Symbols and units . 7
5 Purpose of the test. 8
6 Balance and vibration application categories (BV categories). 9
7 Balancing . 10
7.1 General. 10
7.2 Balance quality grade . 10
7.3 Calculation of permissible residual unbalance. 10
8 Fan vibration. 11
8.1 Measurement requirements . 11
8.2 Fan support system . 15
8.3 Fan vibration limits for tests in manufacturer's work-shop . 15
8.4 Fan vibration limits for operation in situ . 15
9 Other rotating components. 16
10 Instruments and calibration. 17
10.1 Instruments. 17
10.2 Calibration. 17
11 Documentation . 17
11.1 Balance. 17
11.2 Fan vibration. 17
11.3 Certificates. 18
Annex A (informative) Relationship of vibration displacement, velocity and acceleration for
sinusoidal motion . 20
Annex B (informative) Assembly practices for balancing in a balancing machine. 22
Annex C (informative) Sources of vibrations. 24
Annex D (informative) Equation of vibration . 30
Annex E (informative) Vibration and supports . 32
Annex F (informative) Out of balance and bearing reactions . 33
Annex G (informative) Condition monitoring and diagnostic guidelines . 36
Annex H (informative) Suggested relaxation of specified grades and levels . 37
Bibliography . 38

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14694 was prepared by Technical Committee ISO/TC 117, Industrial fans.
iv © ISO 2003 — All rights reserved

Introduction
ISO 14694 is a part of a series of standards covering important aspects of fans which affect their design,
manufacture and use. This series includes ISO 5801, ISO 5802, ISO 12499, ISO 13347, ISO 13348,
ISO 13349, ISO 13350, ISO 13351, ISO 14695 and CEN/BTS 2/AH 17.
This International Standard addresses the needs of both users and manufacturers of fan equipment for a
technically accurate but uncomplicated set of information on the subjects of balance precision and vibration
levels.
Vibration is recognized as an important parameter in the description of the performance of fans. It gives an
indication of how well the fan has been designed and constructed and can forewarn of possible operational
problems. These problems may be associated with inadequacies of support structures and machine
deterioration, etc.
Although alternative standards exist which deal with vibration of machines generally (e.g. ISO 10816), they
currently have limitations because of their universal nature, when considering a specific family of machines
such as fans, with installed powers below 300 kW.
Vibration measurements may therefore be required for a variety of reasons of which the following are the most
important:
a) design/development evaluations;
b) in situ testing;
c) as information for a condition-monitoring or machinery health programme (ISO 14695:2003, Annex C
gives recommended measuring positions for machinery health measurement);
d) to inform the designer of supporting structures, foundations, ducting systems, etc., of the residual
vibration which will be transmitted by the fan into the structure;
e) as a quality assessment at the final inspection stage.
NOTE All the information which can be obtained from tests conducted in accordance with this International Standard
(see Clause 10 of ISO 14695:2003) is neither necessary nor appropriate for quality-grading purposes.
Whilst an open inlet/open outlet test may be useful as a quality guide, this International Standard recognizes
that the vibration of a fan will be dependent upon the aerodynamic duty specified, which determines the
rotational speed and position on the fan.
This International Standard should be read in conjunction with ISO 10816-1, ISO 10816-3 and ISO 14695
which describe the methods to be used and the positions of the transducers. When information is required on
vibration transmitted to ducting connections or foundations, then this is especially important. The gradings
included are such as are generally recommended for commercially available fans.
It is important to remember that vibration testing can be extremely expensive, sometimes considerably in
excess of the fan’s initial cost. Only when the functioning of the installation may be affected should discrete
frequency or band limitations be imposed. The number of test points should also be limited according to the
usage envisaged. Readings at the fan bearings are of most importance and for normal quality gradings should
be sufficient.
INTERNATIONAL STANDARD ISO 14694:2003(E)

Industrial fans — Specifications for balance quality and
vibration levels
1 Scope
This International Standard gives specifications for vibration and balance limits of fans for all applications
except those designed solely for air circulation, for example, ceiling fans and table fans. However, it is limited
to fans of all types installed with a power of less than 300 kW or to a commercially available standard electric
motor with a maximum power of 355 kW (following an R20 series). For fans of greater power than this, the
applicable limits are those given in ISO 10816-3. Where the fans in an installation have varying powers both
above and below 300 kW, and have been the subject of a single contract, then the manufacturer and
purchaser shall agree on the appropriate standard to be used. This should normally be based on the majority
of units.
Vibration data may be required for a variety of purposes as detailed in Clause 5.
The International Standard recognizes that vibrational measurements may be recorded as velocity,
acceleration or displacement either in absolute units or in decibels above a given reference level. The
magnitude of vibration measurements may be affected by assembly practices at balancing machines (see
Annex B). The preferred parameter is, however, the velocity, in millimeters per second (mm/s). As the
conventions vary in different parts of the world, both r.m.s. (root mean square) and peak-to-peak or peak
values are given. It should also be remembered that a fan and its parts may be considered as a spring-mass
system. An understanding of this fact helps to resolve most vibrational problems (see Annex D).
Account has also been taken of the fact that factory tests are usually conducted with the fan unconnected to a
ducting system, such that its aerodynamic duty may be considerably different from that during normal
operation. It may also be supported on temporary foundations of different mass and stiffness to those used in
situ. Accordingly, such tests are specified with vibration measured “filter-in”. In situ tests are specified
“filter-out” and as such represent a measure of overall vibration severity.
This International Standard covers fan equipment with rigid rotors, generally found in: commercial heating,
ventilating and air conditioning, industrial processes, mine/tunnel ventilation and power-generation
applications. Other applications are not specifically excluded. Excluded are installations which involve severe
forces, impacts or extreme temperatures. Any or all portions of this International Standard, or modifications
thereof, are subject to agreement between the parties concerned.
Fan-equipment foundations and installation practices are beyond the scope of this International Standard.
Foundation design and fan installation are not normally the responsibilities of the fan manufacturer. It is fully
expected that the foundations upon which the fan is mounted will provide the support and stability necessary
to meet the vibration criteria of the fan as it is delivered from the factory.
Other factors, such as impeller cleanliness, aerodynamic conditions, background vibration, operation at
sp
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