BS 848-6:1989

Foreword
Committees responsible
Method
Section one. General
1. Scope
2. Definitions
3. Symbols and units
Section two. Method of measurement
4. Mounting of test rig
4.1 General
4.2 Resilient base mounting of fan
4.3 Resilient elastic rope mounting of fans
4.4 Stiff mounting of fans
4.5 Flexible connections
5. Calibration
5.2 Instrument system
5.3 Transducers
5.4 Piezoelectric accelerometers
5.5 Preamplifiers
5.6 Analysers
5.7 Indicators
5.8 Outputs
6. Transducer attachment
6.1 General
6.2 Attachments
7. Selection of measuring positions
7.1 General
7.2 Mounting on combination base frame
8. Test environment and operating data
9. Procedure
9.1 General
9.2 Measurement parameters
9.3 Frequency analysis
10. Presentation of results
Appendices
A. Guide to calculating resilient mount positions
     and rigid body natural frequencies
B. Secondary measurement methods for in situ testing
     or quality grading
C. Recommended measuring positions for machinery
     health measurements
D. Relationship between absolute and decibel levels
E. Relationship between vibration magnitudes of
     single frequency signal
Tables
1. Recommended maximum frequencies for transducer
     mouting
2. Reference levels
Figures
1. Example of resilient mounting arrangement of a
     fan vibration test rig
2. Example of arrangement for testing roof extraction
     fan
3. Degrees of freedom
4. Examples of resilient elastic rope mounted fans
5. Nominal value of relative sensitivity and limits
     of permissible deviation
6. Typical mounting block for transducer
7. Recommended measuring positions for axial flow
     fans
8. Recommended measuring positions for centrifugal
     fans
9. Example showing an indirectly driven centrifugal
     fan assembly on resilient mounts
10. General layout of a centrifugal fan assembly on
     resilient mountings
11. Recommended measuring position for machinery
     health measurement of axial flow fans
12. Recommended measuring position for machinery
     health measurement of centrifugal fans
13. Machine vibration nomogram to convert absolute
     values to decibel levels (sinusoidal wave form)

Describes a method of measuring the vibrational characteristics of fans, except those designed solely for air circulation. Describes a general method only and does not give criteria for interpretation of data. Covers the measurement of vibration recorded as overall r.m.s. velocity, acceleration or displacement, or in terms of a frequency spectrum, within the appropriate frequency range. Methods of testing when suspended on elastic ropes or when installed on resilient mountings are included.