Prepared by Health and Safety Laboratory for the …

1 Executive Health and Safety Noise emissions and exposure from mobile woodchippers Prepared by Health and Safety Laboratory for the Health and Safety Executive 2008 RR618 Research Report Executive Health and Safety Noise emissions and exposure from mobile woodchippers Liz Brueck BSc, MIOA Health and Safety Laboratory Harpur Hill Buxton Derbyshire SK17 9JN mobile wood chipping equipment used in forestry and arboriculture generates high levels of noise. Sustained excessive noise exposure leads to gradual hearing damage. This damage results in deafness and tinnitus. Under the Control of Noise at Work Regulations 2005 there is a requirement to control noise exposure by technical and managerial means with hearing protection only used as a last resort. An important noise control measure is the selection of quieter machines. Noise emission data provided by the machine manufacturers and suppliers should enable this selection. Manufacturers are obliged to ensure low noise designs and to provide values for the noise emission under stated operating conditions.

2 It is also recognised that the real world operating conditions will also influence the noise emission and the noise exposure of the operator. The Health and Safety Laboratory performed measurements of the noise emission and operator noise exposure of a range of mobile , hand fed, wood chippers under simulated standard and real world operating conditions. These measurements were made on behalf of the Forestry Commission and Jason Liggins of the Health and Safety Executive s Policy Group - Agriculture and Food Section. The main aims of the work were: 1. To provide information on the noise emission from a range of wood chipping equipment under a range of set, typical use conditions. 2. To provide information on noise exposures from use of this equipment, and the operational factors which influence this including, but not limited to, materials being processed, methods of infeed and position of operator. 3. To ascertain whether there are significant variations between manufacturer s declared noise emissions and emissions under typical use.

3 This report describes the noise measurement procedure and details the results. Technical terms used in this report are explained in a glossary at the end of this report. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy. HSE Books Crown copyright 2008 First published 2008 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: Licensing Division, Her Majesty s Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to ii ACKNOWLEDGEMENTS Thanks are due to James Archer of Tilhill and Paul Webster of Forest Research.

4 They provided invaluable expertise as well as the machines, timber, and facilities used in this trial. iii iv CONTENTS 1 1 2 LEGAL DUTIES FOR MANUFACTURERS AND SUPPLIERS, AND STANDARDS FOR WOODCHIPPERS .. 2 Noise 2 Noise test code .. 3 3 SELECTION OF WOOD CHIPPERS FOR USE IN THE STUDY .. 4 4 MEASUREMENT PROCEDURE .. 6 Operating 6 Measurement 6 5 RESULTS .. 8 Sound power results .. 8 Operator position sound pressure level .. 10 Frequency content of the chipper 12 Direction of the chipper noise .. 12 Half length timber in standard test .. 12 Manufacturer s Data .. 13 6 MATTERS RAISED BY THE 14 Possible impacts WITH HOPPER .. 14 Suitability of noise test code .. 14 Quiet 15 Operator hearing 15 Manufacturers noise data .. 16 7 17 8 18 9 19 10 APPENDIX A FREQUENCY SPECTRA .. 20 11 APPENDIX B CHIPPER PHOTOGRAPHS .. 31 12 GLOSSARY .. 42 v vi EXECUTIVE SUMMARY Objectives 1. To provide information on the noise emission from a range of wood chipping equipment under a range of conditions of typical use.

5 2. To provide information on noise exposures from use of this equipment, and the operational factors, which influence this including, but not limited to, materials being processed, methods of feeding of materials and position of operator. 3. To ascertain whether there are significant variations between manufacturer s declared noise emissions and emissions under typical use. Main Findings 1. Operators may be exposed to sound levels reaching 107dB(A) during typical use. Levels can be reduced to between 95 and 100dB(A) if noise controls seen on a prototype machine are applied. Noise emission is also directional with most noise generally being in the direction of the hopper and the operator. 2. Noise emission is dependent on type of material being processed, especially in the infeed hopper direction. Untrimmed material with soft branches is quieter than trimmed logs. The square cut timber specified by the C standard (BS EN 13525:2005) noise test code creates additional, often dominant, high frequency noise.

6 It is thought these noise characteristics arise from impacts in the infeed hopper. 3. Few manufacturers and suppliers provide noise emission data with details of the applicable operating conditions. Recommendations 1. Effective noise controls seen in a prototype model woodchipper should be applied to other models to reduce noise emission and operator exposure. 2. Users need access to complete noise emission data to allow selection of quiet machines. HSE should encourage the provision of this data as required by regulations. 3. The noise test code in the C standard would benefit from revision, to include a more realistic wood and reporting of the average emission rather than selected values. 4. Simple noise controls to the hopper should be tried on machines showing strongly directional noise to the hopper side. vii viii 1 INTRODUCTION mobile wood chipping equipment used in forestry and arboriculture generates high levels of noise.

7 Sustained excessive noise exposure leads to gradual hearing damage. This damage results in deafness and tinnitus. Under the Control of Noise at Work Regulations 2005 there is a requirement to control noise exposure by technical and managerial means with hearing protection only used as a last resort. An important noise control measure is the selection of quieter machines. Noise emission data provided by the machine manufacturers and suppliers should enable this selection. Manufacturers are obliged to ensure low noise designs and to provide values for the noise emission under stated operating conditions. It is also recognised that the real world operating conditions will also influence the noise emission and the noise exposure of the operator. The Health and Safety Laboratory performed measurements of the noise emission and operator noise exposure of a range of mobile , hand fed, wood chippers under simulated standard and real world operating conditions.

8 These measurements were made on behalf of the Forestry Commission and Jason Liggins of the Health and Safety Executive s Policy Group Agriculture and Food Section. The main aims of the work were: 1. To provide information on the noise emission from a range of wood chipping equipment under a range of set, typical use conditions. 2. To provide information on noise exposures from use of this equipment, and the operational factors which influence this including, but not limited to, materials being processed, methods of infeed and position of operator. 3. To ascertain whether there are significant variations between manufacturer s declared noise emissions and emissions under typical use. This report describes the noise measurement procedure and details the results. Technical terms used in this report are explained in a glossary at the end of this report. 1 2 LEGAL DUTIES FOR MANUFACTURERS AND SUPPLIERS, AND STANDARDS FOR WOODCHIPPERS Under the Supply of Machinery ( Safety ) Regulations 1992 manufacturers and suppliers of machinery have a legal duty to produce machinery with minimized noise emissions, and to provide information on the noise emitted.

9 As an aid to compliance EN ISO 12100-1 defines a range of standards to specify the Safety requirements for machinery and equipment. Within this range C-standards relate to specific types of machinery and equipment. C-standards define the range of design and construction criteria related to the Safety requirements and give verification tests for these. The C-standard for wood chippers is BS EN 13525:2005. This standard includes examples of how and where noise may be controlled and a noise test code for the determination of the noise emission and the operator noise exposure. Manufacturers may choose to follow part or all of the C-standard, or choose to comply directly with the regulations by other means so for example declare noise according to the standard test method, or declare using their own appropriate test method. NOISE CONTROL In section the BS EN 13525:2005 considers noise sources and noise controls.

10 The text is quoted below. The paragraph numbering is as given in the standard. Noise reduction at source by design and by protective measures The machine shall generate a noise level as low as practicable. The methodology for designing low-noise machinery described in EN ISO 11688-1 shall be used. The main sources causing noise in wood chippers include Infeed mechanism; Chipping components; Chip discharge; Power source The noise reduction measures by design include Selecting low noise components engine; Selecting proper materials; Selecting proper thickness and coating of surfaces; Optimisation the knife mounting configuration; Optimisation of the knife/feeding angle; Selecting low noise exhaust system. 2 Noise reduction by information If after taking all possible technical measures for reducing noise at the design stage a manufacturer considers that further protection of the operator is necessary, then the instruction handbook shall: Recommend the use of low-noise operating modes, and/or limited time operation; Give a warning of the noise level and recommend the use of ear protection.