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Disclaimer: The author is not attempting to present himself as an authority on all available CM standards. This blog is simply an attempt to help those who may be unaware that such guidance exists or of the extent of such standards.

We previously discussed a series of international standards pertaining to condition monitoring of industrial equipment with vibration analysis in, Condition Monitoring & Vibration Classification Standards Awareness: Part 10 ISO 13373-1:2002. This blog is number 11 in a series of blogs describing some international standards as a help to our Ludeca partners. This blog is about the ISO 14694:2003 standard that concerns itself with “Industrial fans” and specifically provides guidance and framework for arriving at acceptable operating vibration levels due to unbalance, as well as acceptance (start-up) levels. It deals with fans used for different applications and offers guidance for determining start-up (acceptance), alarm, and shut-down levels for fans used in the differing applications.

The following three paragraphs are from the ISO introduction to the 14694:2003 standard:

“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.”

There are at least 5 notable tables in this standard:

Table 1 Fan application categories

Table 2 Balance quality grades

Table 3 Percentage of total available clearance within the bearing in each axis

Table 4 Vibration-levels limit for test in manufacturer’s workshop

Table 5 Seismic vibration limits for tests conducted in situ

This standard is titled:

ISO 14694:2003

Industrial fans — Specifications for balance quality and vibration levels

The scope of this standard is quoted below from the ISO.org preview page (quotation in bold):

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 speeds other than those agreed upon, and maintenance of the fan, affect the fan-vibration levels but are beyond the scope of this International Standard.

This International Standard is intended to cover only the balance or vibration of the fan and does not take into account the effect of fan vibration on personnel, equipment or processes.

To read the ISO’s preview of this standard, click here.

This concludes our series of planned standards blog posts. Requests for further informational blogs on standards will be considered. Thank you for your attention.