Human Vibration Introduction, Legislation and Standards Metra Mess- und Frequenztechnik Radebeul /...
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Human Vibration Introduction, Legislation and Standards Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.dewww.MMF.de Slide 2 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de2 Effects of Vibration at Workplaces Human Vibration Hand-Arm VibrationWhole-Body Vibration Working with hand-held machines or driving mobile work machines and vehicles may cause damage to bones, joints, muscles and circulatory problems in the hand-arm system as well as disk damage to the spine. Slide 3 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de3 Activities with Potential Health Risk Whole-Body Vibration: Tractor driving Armored fighting vehicles, e.g., tanks Earth-moving machinery - loaders, excavators, bulldozers, graders, scrapers, dumpers, rollers Forest machines driving Mine and quarry equipment Forklift trucks Some trucks Some bus and tram driving Some helicopters and fixed-wing aircraft Some concrete production machinery Some railway driving Some sports activities etc. Source: Michael J. Griffin / ILO Hand-Arm Vibration: Hand-held powered tools used in manufacturing: percussive metal- working tools, grinders and other rotary tools, impact wrenches etc. Quarrying, mining and construction: rock-drills, stone-hammers, pick- hammers, vibro-compactors etc. Agriculture and forestry: chain saws, brush saws, barking machines, lawn mowers etc. Public utilities: road and concrete breakers, drill-hammers, hand-held grinders etc. Slide 4 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de4 Legislation and Standards EC Vibration Protection Directive 2002/44/EC Measurement and evaluation of human exposure to hand-transmitted vibration ISO 5349:2001 Evaluation of human exposure to whole-body vibration ISO 2631:1997 Human Response to Vibration Measuring Instrumentation ISO 8041:2005 Slide 5 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de5 EC Directive 2002/44/EC Since the implementation of the EC Vibration Protection Directive 2002/44/EC there has been an obligation on companies throughout Europe to assess the risks of jobs involving vibration. The directive defines minimum requirements for employers and manufacturers of machines. For evaluation daily vibration exposure A(8) is used: where a hv is the total vibration value of the frequency weighted acceleration during the exposure, calculated on the basis of the standards ISO 5349 for hand-arm vibration and ISO 2631 for whole-body vibration T e is the total duration of exposure during one work day T 0 is the reference duration of 8 hours Slide 6 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de6 EC Directive 2002/44/EC The directive lays down the following limit values for the daily vibration exposure A(8): A(8) limit valuesHand-Arm VibrationWhole-Body Vibration Exposure Action Value2.5 m/s0.5 m/s Exposure Limit5 m/s1.15 m/s Slide 7 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de7 EC Directive 2002/44/EC Once the exposure action value is exceeded, the employer shall establish and implement a program of technical and and organizational measures intended to reduce to a minimum exposure to mechanical vibration, taking into account in particular: Other working methods that require less exposure to mechanical vibration Appropriate work equipment of ergonomic design, producing the least possible vibration Provision of auxiliary equipment that reduces the risk of injuries, such as protective gloves or special seats Appropriate maintenance programs for work equipment Design and layout of workplaces Adequate information and training to instruct workers to use work equipment correctly and safely Limitation of the duration and intensity of the exposure Work schedules with adequate rest periods Provision of clothing to protect workers from cold and damp In any event, workers shall not be exposed above the exposure limit value. If this should be the case, the employer shall take immediate action to reduce exposure below the exposure limit value. Slide 8 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de8 Hand-Arm Vibration Standard ISO 5349 General Requirements: The used measuring equipment must conform to ISO 8041 Vibration should be measured in three orthogonal directions simultaneously The sensor must be capable of measuring the highest peak acceleration magnitudes The sensor should be mounted as close as possible to the center of the handle without affecting normal use of the machine In the case of machines which need to be held with both hands, measurements must be made on each hand. The exposure is determined by reference to the higher value of the two Measurand is the interval RMS of frequency-weighted acceleration in m/s Slide 9 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de9 Hand-Arm Vibration Standard ISO 5349 Weighting Filter: The weighting filter Wh represents the relative health risk of certain vibration frequencies for the hand-arm system Slide 10 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de10 Hand-Arm Vibration Standard ISO 5349 Interval RMS: Interval RMS values a wx, a wy and a wz should be measured and reported for X, Y and Z separately To minimize variation, vibration should be measured, if possible, several times during a work day and averaged: where a hwi is the interval RMS of measurement i n is the number of measurements t i is the duration of measurement i The measuring time shall be sufficiently long to provide representative values for a machine or activity. The duration of one measurement should be more than 8 seconds. The total measuring time should be at least 1 minute. Slide 11 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de11 Hand-Arm Vibration Standard ISO 5349 Total Vibration Value: Evaluation is performed on the basis of Total Vibration Value a hv, which is the square root of the sum of the squares (vector sum) of the interval RMS values a wx, a wy and a wz : In certain cases it may be not possible or not necessary to measure the RMS in three axes for the calculation of a hv. The results of uniaxial measurements must be multiplied with a correction factor. The factor can vary from 1.0, if there is only one dominating axis, to 1.7, if all three axes have simi lar values: where a wmeas is the measured RMS value for one dominating axis for three similar axes Slide 12 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de12 Hand-Arm Vibration Standard ISO 5349 Daily Exposure: The health risk depends on the duration of vibration exposure during a work day Daily exposure A(8) is the equivalent continuous acceleration over an eight-hour work period. For the determination of A(8) it is not necessary to measure over eight hours. It is sufficient to make short-term measurements during representative work steps. The results are normalized to eight hours. Daily exposure is calculated as follows: where a hv is the total vibration value of the frequency weighted acceleration during the exposure T e is the total duration of exposure during one work day T 0 is the reference duration of 8 hours Slide 13 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de13 Hand-Arm Vibration Standard ISO 5349 Combined Daily Exposure: If a daily exposure consists of more than one activity with different vibration magnitudes, daily exposure is calculated: where a hvi is the total vibration value of the frequency weighted acceleration of activity i n is the number of activities T i is the duration of activity i To compare the contributions of different activities, it may be useful to calculate partial exposure values: Slide 14 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de14 Hand-Arm Vibration Standard ISO 5349 Daily exposure should be measured for both hands separately Since measurement uncertainty is usually relatively high (e.g. 20 to 40 %), not more than two significant digits should be stated for A(8) Slide 15 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de15 Hand-Arm Vibration Standard ISO 5349 Measuring Report: The result of measurements to ISO 5349 shall be a report including the following data: Names of company / contractor and operating person Purpose of measurement Date Location Temperature, humidity, noise Description of activities Work procedure (working time, interruptions, breaks) Tested equipment (model, serial no., condition, age, weight, rotary speed, handle type), tools and work pieces Measuring equipment (type, serial no., calibration date, function chaeck Sensor positions and directions, mounting method Measured interval RMS in X / Y / Z direction for each activity Total vibration value A hv for each activity Duration T i of each activity for one work day Daily vibration exposure A(8) Partial Daily vibration exposure A i (8), if measured Slide 16 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de16 Hand-Arm Vibration Standard ISO 5349 Function Check and Calibration: It is recommended to perform a function check of the sensor and the measuring instrument before and after each measurement by means of a vibration calibrator Calibration should be performed in regular intervals, e.g. after 2 years, in order to check that the equipment is within the specification to ISO 8041 Slide 17 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de17 Hand-Arm Vibration Standard ISO 5349 Practical sensor locations for various machine tools: Chain sawAngle grinder Straight handle Grinding machine Chipping hammer Steering wheel More examples of measuring points can be found in ISO 8662 for various hand-held machines, ISO 7505 for chain saws and ISO 7916 for portable brush saws. Slide 18 Metra Mess- und Frequenztechnik Radebeul / Germany www.MMF.de18 Whole-Body Vibration Standard ISO 2631-1 General Requirements: ISO 2631-1 covers methods for the measurement of periodic, random and transient vibration with regard to health, comfort and perception The consider