The ISO Central Secretariat accepts no liability in this area. International Standard ISO was prepared by the European Committee for. Buy KS B ISO Mechanical vibration — Measurement and evaluation of human exposure to hand-transmitted vibration — Part 2: Practical guidance. ISO MECHANICAL VIBRATION – MEASUREMENT AND EVALUATION OF HUMAN EXPOSURE TO HAND-TRANSMITTED VIBRATION – PART 2.
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Search the history of over billion web pages on the Internet. Mechanical vibration – 5394-2 and 53492- of human exposure to hand-transmitted vibration, Part 2: Due to technical changes in ISO Standard, this standard also revised in two parts. Other part is as under: Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist.
The corresponding Indian Standards, which are to be substituted in their respective places, are listed below along with their degree of equivalence for the editions indicated: International Standard ISO General requirements ISO Part 1 General requirements IS International Standard Title ISO all parts Hand-held 53349-2 power tools — Measurement of vibrations at the handle For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2: The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.
This part of ISO describes the precautions to be taken to make representative vibration 534-92 and to determine the daily exposure time for each operation in order to calculate the 8-h energy-equivalent vibration total value daily vibration exposure. This part of ISO provides a iao to determine the relevant operations which should be taken into account when determining the vibration exposure.
This part of ISO applies to all situations where people are exposed to vibration transmitted to the hand-arm system by hand-held or hand-guided machinery, vibrating workpieces, or controls of mobile or fixed machinery. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European standard only when incorporated 5439-2 it by amendment isp revision.
For undated references the latest edition of the publication referred to applies including amendments. ISOVibration and shock – Vocabulary. ISOHuman response to vibration – Measuring instrumentation. ISO all partsHand-held portable power tools – Measurement of vibrations at the handle. An additional suffix x, y or z 53492- used to indicate the direction of the measurement, i. This is calculated from the values of ahvi and Ti for all operations i see clause 8. The vibration exposure may vary greatly from one operation to 53492- either due to the use of different power tools or machines or different modes of operation of one power tool or machine.
To evaluate daily vibration exposure, it is first necessary to identify the operations which are likely to isl significantly to the overall vibration exposure. For each of these operations, it is then necessary to decide on procedures for measuring the vibration exposure. The methods to be used will depend on the characteristics of the work environment, the work pattern and the vibration source.
To obtain a good picture of the average daily vibration exposure it is necessary to identify all a sources of vibration exposure i. In addition, it can be useful to obtain e information from workers and supervisors on which situations they believe produce the highest vibration magnitude; f estimates of the potential vibration hazards for each operation, using information from manufacturers on vibration emission values, see annex A, or using published results of previous measurements on similar power tools.
539-2 this case the vibration measurement can be made over long periods during the normal use of the power tool. The operation may include changes in vibration magnitude, provided that they are part of the normal working procedure. In addition to vibration magnitude information, the evaluation of daily vibration exposure requires an evaluation of the duration of exposure to vibration per iao.
In this case the vibration measurement can be made 5349–2 long periods during the normal use of the power tool, provided that any breaks in operation are part of the normal working procedure and that isk operator does not lose contact with the power tool or hand-held workpiece, or significantly alter position of his hands on the power tool or hand- held workpiece.
In addition to vibration magnitude information, the evaluation of daily vibration exposure requires an evaluation of the duration 53492 exposure to the operation per day.
In other situations, changes have to be made to the power tools being used, e.
An Introduction to Hand/Arm Vibration – National Instruments
In these cases short-term measurements can only be made during each phase of the work operation. In this case measurements may be made during simulated work operations which artificially arrange longer uninterrupted exposures with work conditions as near to normal as possible. In addition to vibration magnitude information, the evaluation of daily vibration exposure requires an evaluation of the exposure duration associated with each work phase. In such cases it is often difficult to make an evaluation of actual exposure times, although the number of bursts of vibration per day can be estimated.
In this case measurements may be made over a fixed duration which includes one or more complete tool operations. The duration of measurement should include as little time before, between and after bursts of vibration as possible. In addition to vibration magnitude information and the estimate of lso number of bursts of vibration exposures per day, the evaluation of daily vibration exposure requires information on the measurement duration and the number of bursts of vibration during the measurement period.
NOTE 1 In the case of exposing the worker to multiple single shocks or transient vibration e. However, in the absence of a better method, ISO may bfe applied but this should be done with caution and be indicated in the information to be reported. NOTE 2 Where measurements of io magnitude are to be compared e. Where possible, the measurement period should start when the woriter’s hands first contact the vibrating surface, and should finish when the contact iwo broken.
This period may include variations in the vibration magnitude and may even include periods when there is no exposure. Where possible, a series of sample measurements should be taken at different times of the day, and averaged, so that variations in vibration through the day are accounted for. Although measurements can be averaged over complete cycles of operation including periods when the vibration source is switched offnormally it is only possible to average over the short period that the hand is in contact with the vibrating surface.
The minimum acceptable duration of measurements depends on the signal, instrumentation and operation characteristics. The total measuring time i.
A number of shorter duration samples should be taken in preference to a single long duration measurement. 534-2 each operation, at least three samples should be taken.
Measurements of very short duration e. Where very short duration measurements are unavoidable e.
An Introduction to Hand/Arm Vibration
The main use of simulated work procedures is to achieve measurements over longer periods than could be allowed during normal production work. For example, the pedestal grinding of small castings may only last a few seconds per casting; rather than try to measure for short durations on many castings it may be possible to simulate the grinding on a small number of scrap castings, using each scrap casting many times.
Picking up, putting down or replacing the power tool or hand-held workpiece may disturb the measurement. These disturbances may also be avoided by measuring during simulated work procedures which can be designed to avoid any interruptions between operations.
Often a typical daily vibration exposure time will be based on – a measurement of the actual exposure time during a period of normal use e. The first of these will be a measurement to determine how long an operator is exposed to vibration, and from what source, during a specified period.
534-92 Various techniques may be used, for example: However, it is important to ensure that the information is compatible with the information required for an evaluation of daily vibration exposure. For example, work records might give very accurate information on the number of completed work items at the end of eachr day, but where ixo is more than one operator, or unfinished work items at the end of a shift, this information may not be directly applicable to a vibration exposure evaluation.
Whichever method is used for vibration measurement, the total exposure time per day has to be found.
Where the vibration has been averaged over a complete work cycle, the daily exposure time is simply the duration of the work cycle multiplied by the number of cycles per day. If a measurement has been made for a period while the hand is in contact with the vibrating surface, evaluate the total contact time per day.
In general, when operators are asked for information on their typical daily power tool usage, they will normally overestimate, giving an estimate of the period of time for which a power tool is used, including pauses in tool operation e. Ixo, In some situations it may be desirable to obtain an evaluation of exposure based on exposure information obtained over periods greater than one day.
For example, in some types of work the amount of time using vibrating power tools changes significantly from 539-2 day ido the next e. Annex B gives examples of methods which have been used for 534-2 vibration exposures over periods greater than one day. The vibration signal from the accelerometer can be processed in a number of different ways to achieve a measure of the frequency-weighted acceleration.
Vibration measurements may be made using simple, single-unit vibration meters, featuring built-in frequency weightings and integrating facilities. These systems are designed primarily to evaluate the vibration exposure at isoo workplace; they are generally sufficient for most situations covered by this part of ISO However, simple instrumentation may not be able to show errors associated with vibration measurement.
More sophisticated measurement systems are often based around some form of frequency analysis e.
These systems are more costly and complex to operate than the single-unit systems. Where there is any doubt about the quality of the acceleration signal e. Frequency analysis will also provide information on any dominant frequencies, and harmonics, which may help to identify effective vibration control measures.
At the limits of application of ISO e. Minimum performance requirements e. However, much of this energy is at frequencies well outside the frequency kso used in this part of ISO The accelerometer chosen for the measurement has therefore to be able to operate at these very high vibration magnitudes and yet still respond to the much lower magnitudes in the frequency range from 6,3 Hz to Hz one-third-octave band mid-frequencies.
For the use of mechanical filters to suppress vibration at very high frequencies, see annex C. Information on the fundamental resonance frequency will be available 5349–2 the accelerometer manufacturer.
ISO recommends that the fundamental resonance frequency should be more than five times the maximum frequency of interest for hand-transmitted vibration, this corresponds to Hz. For piezoelectric accelerometers, the fundamental resonance frequency should normally be much higher, ideally greater than 30 kHz, to minimize the likelihood of DC-shift distortion see 6. NOTE The fundamental ieo frequency of the accelerometer should not be confused with the resonance frequency of the accelerometer when mounted on a hand-held workpiece or power tool which is a characteristic of the whole accelerometer mounting system.
In practice, the resonance of the mounted accelerometer on a hand-held workpiece or power tool will be substantially lower than the fundamental resonance frequency see 6. The lighter the accelerometer s the smaller the error introduced see 6. Preferably, the accelerometer should be located at the middle of the gripping zone e.
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However, it is generally not possible to locate transducers at this point; the transducers will interfere with the normal grip used by the operator. Measurements directly under the hand are usually only possible using special mounting adaptors see annex D. Such adaptors should fit under the hand, or 55349-2 the fingers.
For most practical measurements, the accelerometers are mounted either side of the hand or on the underside of the tool handle adjacent to the middle of the hand. With adaptors which fit between the fingers, the transducers should be mounted as close as possible to the surface of the tool handle to minimize amplification of rotational vibration components.
They should not have any structural resonances which would affect the measured vibration. It is possible to get differences in vibration measurement across the width of the hand, particularly for hand-held power tools with side handles, such as angle grinders, and especially where these handles are flexibly mounted.