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Prepared by W S Atkins Consultants Limited for the Health and Safety Executive 2002
RESEARCH REPORT 040
P A Munns, Y Luong & P J Rew W S Atkins Consultants Limited Woodcote Grove Ashley Road Epsom Surrey KT18 5BW United Kingdom
Fire safety guidance in the UK relates primarily to buildings containing ordinary combustible loads, although there is some specific guidance and data relating to the storage of flammable substances, liquids and gases. A study was undertaken with the purpose of assessing the effectiveness of current UK guidance relating to the control of fire hazards in workplaces containing flammable substances. Incident data relating to fires involving flammable substances in the UK were reviewed. The review concentrated on workplace safety and excluded offshore, mining, waste and transport incidents. The data gathered were assessed to determine those industries and building types for which consideration of fire risk involving flammable substances is critical, and key risk parameters for these cases were identified. The effectiveness of UK guidance in reducing fire risk in workplaces containing flammable substances, and how the efficacy of individual measures can be estimated, was assessed through reference to the incident data. A proposal has been developed for a method for a risk-based assessment of the fire safety within workplaces containing flammable substances. The purpose of the method is to enable high risk buildings or processes to be identified, or else to rank the workplace with respect to risk. This method has been evaluated against incident data to ensure that all the factors known to affect fire risk were incorporated. 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 authors alone and do not necessarily reflect HSE policy.
© Crown copyright 2002 First published 2002 ISBN 0 7176 2157 X 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 hmsolicensing@cabinet-office.x.gsi.gov.uk
3 3.Summary of Guidance Documents APPENDIX D .1 4.1 Identification of incident data 2.3 1.4 6.2 6.1 3.CONTENTS 1.4 4. INTRODUCTION 1.3 Analysis of fire incidents by workplace 6.Development of Risk Assessment Model APPENDIX E .2 Applicability 2. EFFECTIVENESS OF UK GUIDANCE 5.Breakdown of Fire Incidents With Respect to Company Size APPENDIX C .5 5.2 1.Garages Handling Petrol iii .5 Incident review Size of premises and training levels Fire protection measures Fire prevention measures Key risk parameters and industries Background British Standards and building codes HSE documents HSE leaflets Others 4.1 1.2 4.1 Key conclusions of review of incident data and current guidance 7.3 4. Background Objectives and scope of work Methodology Report outline 1 1 1 2 3 4 4 4 5 6 6 8 10 12 14 16 16 16 16 17 17 18 18 18 24 28 28 29 30 32 35 37 37 38 40 41 42 43 49 52 55 WORKPLACE FIRE INCIDENT DATA 2.5 Scope of method Model framework Model sensitivity Model use Summary and model limitations 7.4 3.1 6.Descriptions of Attributes for Risk Assessment Model APPENDIX F .Home Office Fire Statistics 1997 APPENDIX B .3 6.3 Home Office statistics 3.2 Analysis of fire incidents by substance type 5. UK FIRE SAFETY GUIDANCE 4.2 Development of risk assessment method REFERENCES APPENDIX A .Worked Example .2 3. IDENTIFICATION OF KEY RISK PARAMETERS 3. CONCLUSIONS 7. PROPOSAL FOR RISK ASSESSMENT METHOD 6.1 Structure of review 5.4 2.
guidance documents and engineering models.1. The fire precautions required in the workplace are then dictated by the level of fire risk. A proposal has been developed for a method for a risk-based assessment of workplaces containing flammable substances hazards. This pilot study reviews fire incident data and guidance for flammable liquids. 2.2. fire-fighting. 1 .1 INTRODUCTION Background In most industrial operations. particularly during the early stages of an incident. mining. Provide a proposal for a risk assessment method for assessing the hazards to workplaces resulting from the storage of flammable substances.1 Objectives and scope of work Objectives The overall objectives for the research programme were to: 1. gases and other high hazard combustibles in onshore workplaces. The risk depends on the combustibles available for fire development. The purpose of the method is to enable high risk buildings or processes to be identified. codes. It considers how the detailed implementation of specific guidance on the control of flammable substances can prevent workplace injuries and fatalities. 1. The Fire Precautions (Workplace) Regulations 1997 came into force on 1 December 1997 and require that a fire risk assessment is carried out. those which affect fire initiation and the early stages of fire growth) and ‘general fire precautions’ (e. 1. For premises where flammable substances are handled or stored. When designing a structure or system against the effects of fire. Thus it considers how fire risk is affected by the handling and storage of flammable substances in the workplace. transport and explosive sectors have been excluded. fire presents a risk which may be defined in terms of financial loss (infrastructure and business interruption) or life safety of employees and the surrounding population.e. which relate to both fire prevention and fire control. The risk is also influenced by the fire protection measures in place. Fire incidents in the offshore. the geometry of the buildings and the likelihood of ignition.2 1. standards. The Fire Precautions Act 1971 applies to new and old buildings and permits the designation of building types where Fire Certificates must be obtained from the local fire authority. the provision of fire fighting and fire detection. and emergency routes and exits). or else to rank the workplace with respect to risk. their physical arrangement. Review the effectiveness of current guidance on fire safety for flammable substances in the workplace. an engineer is presented with a framework of legislation. This report concentrates on process fire precautions rather than general fire precautions. and by the control of ignition sources. fire alarm systems and limitations on explosive or flammable materials. Fire safety is specifically addressed by the Fire Precautions Act 1971 and the Fire Precautions (Workplace) Regulations 1997.g. The certificates specify that provision should be made for means of escape. The Health and Safety at Work Act (HSWA) 1974 provides a framework for a comprehensive system of law to deal with the health and safety of all people at work. the fire precautions will comprise both ‘process fire precautions’ (i. This method has been evaluated against incident data to ensure that all the factors known to affect fire risk were incorporated.
g. Review and collation of fire risk data: Based on the incident data collated in Task 1. These included parameters such as the type of flammable material stored. waste etc.3 Methodology Task 1 – Effectiveness of Current Guidance 1. and for which consideration of fire risk is critical. Assessment of current UK guidance. Identification of key fire risk assessment issues: The types of buildings and industries in which flammable substances are stored or processed. The study concentrated on ‘process fire precautions’. such as means of escape. · · · · 1. explosives. Thus consideration was given to the handling and storage of flammable substances in the workplace and the control of ignition sources. 5. Onshore establishments were considered. Their relative importance with respect to fire risk was considered for the identified industries. plastic foams. Identification of existing legislation and guidance: A list of significant UK legislation. codes.2 Scope of work A large quantity of data and guidance exists which is of relevance to the storage of flammable substances in the workplace. i. 3. 4. Review of incident data for fires in workplaces: Incident data relating to fires involving flammable substances within the workplace were collated. was therefore limited in scope as follows: · Flammable substances considered in the study were liquids. The occasional use of small quantities of flammable materials was considered on a non industry-specific basis.) have not been considered. The study was limited to UK legislation and guidance. and also through reference to generic data from other industries. 2. construction and transportation sectors were excluded. Consideration was given to how the implementation of the recommendations in codes and standards affects fire risk. standards and guidance relevant to the handling and storage of flammable substances was agreed with the HSE. office equipment. those which affect fire initiation and the early stages of fire growth. Mining. the relative frequency of fire hazards and the probability of fire protection measures being effective was considered. Ordinary combustible materials (e. gases and other high hazard combustibles e.g.1. The study did not consider general fire precautions. control of ignition sources. as a pilot study. Based on the review of fire incident data. implementation of security measures and the training and skills of personnel.2.e. The study considered the effect that the scale and type of an enterprise had on fire risk. were identified. the key parameters affecting fire risk were defined. Thus the effectiveness of 2 . and whether this effect was related to differences in employee numbers or variations in skill and training levels. building materials. storage method. It was not considered practical to include all the available information and the project. except where these influence the initial effects of the fire. except where they exacerbated the risk associated with the high hazard materials.
Section 3 summarises the identification of industry types and key risk parameters.Risk Assessment Method 6.UK guidance on fire risk in workplaces which contain flammable substances was assessed. has been developed. 3 .3. Appendix A summarises the statistical data that were assessed relating to fires involving flammable substances. or else to rank workplaces with respect to risk. Task 2 . A method which can be used to identify high risk buildings. Proposals for risk assessment/identification method. Section 6 discusses the development of the risk assessment method.4 Report outline The report presents the full results of the study and covers each of the activities identified in the methodology outlined in Section 1. Section 2 outlines the review of fire incident data. Appendix F provides a worked example of the risk model for garages handling petrol. to ensure that it incorporates the various factors which are known to have a significant influence on fire risk. Appendix D details the development of the risk model and Appendix E provides the descriptions of workplace attributes used in the risk assessment model. Appendix B provides a brief description of the incidents that were assessed. to determine the influence of company size. Section 5 then considers the effectiveness of guidance. Section 7 summarises the key conclusions of the study. Appendix C provides a summary of the key guidance documents reviewed. facilities or processes that contain flammable substances within a workplace. 1. The method was assessed against incident data. Section 4 defines UK fire safety guidance that was considered in the study.
The assumption made in this study. e. The fire brigade reports were obtained by writing to local fire brigades. Other sources of data identified in the literature search were referred to as appropriate. This process led to 127 incidents being included from HSE . · Loss Prevention Bulletins. These reports were chosen as they were considered to reflect current practices and because they provided sufficient information to enable key risk parameters to be identified. Some incidents were rejected because they contained too little information to be of use.g. 2. · Lees. The second objective was to identify more detailed incident records to enable key risk parameters to be determined and to enable a comparison to be made with the appropriate guidance. giving a total of 135 incidents. the HSE estimate the level of under-reporting of non-fatal reportable injuries to employees to be as high as 40% for the types of workplace considered in this study (based on reporting levels for manufacturing industries between 1997/98 and 1999/2000 [4]). Others were rejected because they were not relevant to the study. ‘Loss prevention in the process industries.Case book of Fire Protection Association (FPA) fires.2 Applicability The main source of information for the study was the HSE data . which require potentially dangerous occurrences. Summary of fire statistics [2]. in the absence of further information. nursing homes and educational establishments. · Fire CD . All incidents reported in 1997/1998 concerning fires were reviewed. For example. is that under-reporting applies equally across the spectrum of workplaces considered in this study and therefore does not unduly affect the results of the incident review. 2. This is from reports filed under RIDDOR [3]. The search of the HSE data was conducted at the HSE offices in Bootle. as well as actual incidents. · Fire incident data reported to HSE . 4 .2. Under-reporting is known to be an issue. · Home Office. Eight fire brigade reports were suitable for the study. The following databases and sources were searched to find information on fires involving flammable substances. one year of incident reports from HSE for 1997/98 and individual fire brigade reports for 1997 were selected from the above list as being most relevant to the needs of this study. The incident numbers were obtained from the Home Office and were supplied as part of a more detailed break down of the 1997 fire statistics.1 WORKPLACE FIRE INCIDENT DATA Identification of incident data A search was carried out to gather incident data on fires that have occurred in the workplace involving flammable substances. to be reported.’ [1]. The Home Office fire statistics. · Individual fire brigade reports. The first objective of the search was to identify data that could be used to determine general trends in fires involving flammable substances. requesting copies of the reports for specific fire incident numbers.
The fire statistics for 1990-1998 were also reviewed to ensure that the 1997 fire statistics were representative.426 fires. However. it should be recognised that the sample size is not of sufficient size to attach wider significance to the results with any certainty. but 20 % of fire deaths.1 also shows that the number of fire deaths resulting from liquid fires was significantly higher than for gases. out of a total of 44. Fires involving flammable liquids represented 6 % of fires. 2. when considered against fires as a whole. the risk of an incident involving gases is no greater than for normal combustible materials. In other years. such as the Fire Protection Association (FPA) analysis of large fires [5]. representing only 3 % of the total. Furthermore. However. the percentage of fatalities caused by liquid fires is either similar to. Fires involving gases were neither significant in terms of number of fires. These show that. Fire and fatalities by material first ignited 40 35 30 % of fire/fatality 25 20 15 Gases (fires) Liquids (fires) Unspecified (fires) Gases (fatalities) Liquids (fatalities) Unspecified (fatalities) 10 5 0 1998 1997 1996 1995 1994 Year 1993 1992 1991 1990 Figure 2. representing only 1 % of the total. or in terms of fatalities. Table A. In 1995 the percentage of fatalities caused by liquid fires was far greater than those caused by unspecified materials. those caused by unspecified materials. gases are less common in use and they may still represent a greater hazard than ordinary combustible materials on a workplace by workplace basis. 5 . or less than. This shows that for the whole period significantly more fires involved flammable liquids than gases. but 33 % of fatalities.The 135 incidents provided a reasonable sample for this pilot study and were complimented by additional incident surveys. where appropriate. unspecified causes accounted for approximately 10 % of fires.1 in Appendix A summarises Table 19 of the Home Office report which gives deaths and casualties for fires in buildings other than residential by material or first item ignited.3 Home Office statistics The Home Office 1997 fire statistics [2] were assessed to determine the involvement of flammable substances in incidents where injuries and fatalities occurred.1 Home Office Fire Statistics (1990 –1998) The statistics show that the presence of flammable liquids is a key risk indicator. The information provided in the 135 incidents was considered to be sufficient for the identification of key parameters and weightings for the model developed in Section 6. and this is considered in more detail in the following sections.1 below. Figure 2. The results of the review are summarised in Figure 2.
manufacturing and garages as building types where a risk assessment is considered critical.3. a total of 135 incidents from the HSE and Fire brigade reports are included in the analysis conducted in this study. through detailed review of selected incident descriptions. but where the incident report showed that hot work was the ignition source.1 IDENTIFICATION OF KEY RISK PARAMETERS Incident review Methodology As discussed in Section 2.1. out of the full sample of 135. substance ignited. For 6 warehouse 10 power food printing unspecified 25 unspecified (hotwork) . Consideration is given to the effectiveness of fire protection and prevention measures in Sections 3.1 below gives the number of incidents. in order to assess the effect of workplace size on fire risk. including steel mills and die-casters.4. chemical 35 30 manufacturing Number of Incidents 20 foundry 15 garage 5 0 Figure 3. It is noted that the incident data used in the following analysis is limited to a single year (1997/98) and caution should be exercised in interpreting this data. ‘chemical’ included pharmaceutical and process facilities.1 Fire incidents against workplace type The figure identifies chemical. foundries. and cause of ignition.1 3. the full data are assessed with respect to workplace type. where workplace size could be determined. This is mainly due the limited number of incidents being analysed (especially where a subset of 41 is used when considering workplace size). The high number of chemical industry incidents is due to the fact that flammable substances are being processed in these industries. When considering workplace type.2 reviews a subset of 41 incidents.3 and 3. that occurred in each workplace type.1. However.1. it is considered that there are sufficient incident records to be able to draw some broad conclusions and to rank workplace features or work practices with respect to their contribution to fire risk. Section 3. but also because the incidents are only representative of working practices occurring during the one year period. 3. when the workplace type could not be identified. ‘Hotwork’ was entered as a workplace type.2 Workplace type Figure 3. ‘Foundries’ included all incidents where hot metal was being processed. 3. In each of the sections below.
which is significantly higher than in the general trends shown in the Home Office statistics [2]. 3. Therefore. the incident reports show that the main cause of reported incidents was due to workers being in close proximity of high temperature equipment and gases. Gases. For the garage incidents it is the presence of petrol and the casual nature of its treatment that is the most significant cause of the incidents.2 below details the material first ignited from the 135 incident reports.3 Material Ignited For the purpose of this study. Flammable Liquids.2 Material first ignited The pie chart confirms the presence of flammable liquids as a key risk indicator. The percentage of fires involving gases is approximately 16%.foundries. There are no common trends emerging from the incident reports for manufacturing. § § § Figure 3. Given 7 . Normally defined as liquids with flash points below 55oC but in the incident review defined as all combustible liquids other than HFLs. Defined as liquids with flash points below 32oC and hence those which give off flammable vapour at or below normal atmospheric temperatures. Note that all incidents where the material ignited was named as a solvent were placed in the highly flammable liquid (HFL) category. solid 25% highly flammable liquid 29% gas 16% flammable liquid 30% Figure 3.e. Defined as flammable gases. 59% of the total number of incidents. but for the purpose of this study also includes oxygen. including dusts.1. This may be due to differences in reporting. but were rightly reported under RIDDOR as a dangerous occurrence. unless it was obvious from the descriptions that they were not HFLs. which although not flammable is considered to be a fire hazard as its presence in above atmospheric concentrations increases the fire hazard of other materials. The number of incidents involving highly flammable liquids and other flammable liquids is 78. materials are divided into the following 4 categories: § Highly Flammable Liquids (HFLs). The majority of the incidents which involved gases were minor and did not require the fire brigade to attend. All solid combustible materials. they would not be reflected in the Home Office Statistics. Solids. i.
in most workplaces. solids includes ordinary combustible materials which.4 Cause of ignition Figure 3.that incidents involving gases represent 16% of the total. The eight fire brigade incident reports also provided the number of employees within the building. However. When selecting the incidents. garage fires were specifically excluded.1 Size of premises and training levels Incident selection A total of 41 incidents were reviewed to determine whether company size affects safety. electrical and heat (hot surfaces) are the most prevalent. hotwork. 25 hotwork 20 electrical heat unspecified other Number of incidents 15 flame 10 friction static 5 0 Figure 3. will be present in greater quantities than flammable liquids and gases. The number of fires initially involving solids is higher than those involving gases.3 below details the breakdown of the 135 incidents with respect to the cause of ignition. the presence of flammable solids is not seen as a key risk parameter. Other sources (such as smoking. The study then considered whether any relationship could be drawn between company size and the effect of training and staff awareness.2.2 3. Furthermore. with friction and static causing ignition in approximately half as many incidents.1. ‘unspecified’ means that the cause of ignition could not be identified. Therefore. as they were already known to be small companies and including them would have distorted the number of small 8 . flames. the presence of gas is a key risk indicator. the incident data reviewed in Section 5.3. Therefore. 33 incidents were selected from HSE data. hot particles and autoignition) were the cause of ignition in 21 incidents but were not individually significant. 3. of the identifiable causes.3 Cause of Ignition In Figure 3. on the basis of their incident reports having sufficiently detailed descriptions with respect to the part that training or awareness played in the incident.2. and hence how the latter affects safety. The number of employees was provided separately by the HSE. 3.4 suggests that few injuries result from fires involving solids.
1 below gives the number of people employed in each company size band and the percentage of the total based on a total working population of approximately 21. the company size and a comment on each of the selected incidents.9 2. Possible reasons for this could be improved levels of employee training or implementation of company procedures or safe working practices. self employed and partnerships Table 3. which shows that the majority of incidents occurred because of poor working practices involving the careless use of petrol. there were inadequate company procedures or careless working practices. 3. Figure 3.companies in the sample selected.8 6. it appears that large companies do favourably with the smallest number of incidents despite employing the greatest number of people. based on a survey at the start of 1998 [6]. This is recognised as an ongoing issue by the HSE and they have developed special initiatives aimed at garages.3. This result could be used to suggest that.2. Table 3. Not withstanding this. Note also that the above bands are similar to those used by the HSE.5 9. in the larger companies.2 DTI information and statistics The company size was classified using the following DTI bands: Micro Small Medium Large 0-9 employees 0-49 employees (includes Micro) 50-250 employees over 250 employees Note that for simplicity. The individual incidents in garages are detailed in Section 5.2.3 Results Table B1 in Appendix B details the incident number.4 Percentage of total 13 % 32 % 12 % 43 % * includes sole trading companies.4 shows the number of incidents relative to company size in graphical form.1. There is some uncertainty introduced to the analysis due to the small number of incidents (41) for which company size could be determined. it does suggest that a definite link cannot be drawn between occurrence of accidents and provision of training or implementation of company procedures or safe working practices. Micro firms are usually included within the ‘Small’ band. review of the incident reports shows that in 33% of the incidents in large companies.1 Break down of employment by industry type [6] 3. as shown above. accidents rates are reduced. 9 . Although this does not necessarily mean that the incidents occurred due to inadequate procedures or careless working practices. Size of company None* Small (0-49) Medium (50–249) Large (250 +) Number employed in millions 2.6 million. The DTI provided data on the number of employees that work in different sizes of companies. However.
However.4 Number of incidents against company size When considering small companies it should be noted that there were no obvious companies within the incident data which fitted into the ‘none’ category of company size. with the same percentage of incident reports referring to poor working practices as for large companies at 33%. However. no conclusions could be drawn regarding the link between company size and the quality of training or implementation of safe practices within the workplace. 3. for two incidents. the difference is not significant and this suggests that the record of small companies in fire safety is not appreciably worse (if at all worse) than that of larger firms. Based on the available data. as only 20% of the incident reports referred to failures in procedures or working practices.4. the conclusion of the analysis of the effects of company size is that it appears not to be a major factor in determining the risk of an incident occurring. it is noticeable that the incidents recorded for small companies tended to lead to more serious injuries and.3 Fire protection measures The presence of active fire safety measures was identified in only twelve of the incidents considered (less than 10% of the total).16 14 12 Number of Incidents 10 8 6 4 2 0 small medium Company Size large Figure 3. However. when the incident data is reviewed this is shown to be probably coincidental. the number of incidents considered is slightly higher than for large companies. However. Despite employing the smallest percentage of the working population. fatalities. The standard RIDDOR reporting form does not require the role of active measures to be detailed and their presence can only be identified if included in the descriptive section (and no mention of active measures does not necessarily infer their absence or effectiveness/ineffectiveness). the relatively low number of 10 . while the percentage of the working population employed in small firms is slightly lower. For small companies. medium sized companies have the highest number of incidents out of the 41 considered in Figure 3. The majority of incident reports suggested that medium size companies actually had good working practices. However. especially in terms of severity of injuries. The incident review tends to support this. Employees of smaller companies appear to be at a slightly greater risk. serious accidents also occurred in medium and large companies which appeared to be related to poor working practices and failure to follow appropriate guidance. Based on the limited data set.
gives seven examples where sprinklers failed to operate soon enough to protect the life of workers in the immediate proximity of flash fires. Research at the Fire Research Station [8] has shown that. Smoke detection has an important life safety role in that it ensures that occupants remote from the fire are warned of the potential dangers. There are very sensitive systems such as aspirating detectors. However. in specially controlled environments. smoke detection is unlikely to provide any advance warning and therefore will not make a significant contribution to reducing the immediate hazard. or explosions. However. or explosions. The difficulty in deriving definite conclusions from this study is that there are insufficient details to judge how close the workers were to the incident in comparison to the incidents where people did not survive. The effectiveness of a system is highly dependent on the flammable material. unless they allow increased time for evacuation from a building by slowing fire development. a warehouse fire. will detect a fire at a very early stage. the fire brigade was summoned and the extent of damage limited. but the operation of sprinklers was credited with saving their lives. or water curtains shielding people from radiation from a severe fire hazard. this does not mean that a sprinkler system will be effective in controlling 95% of fires. There is some evidence to support this. Data on sprinkler reliability given by [7] suggests that a properly maintained system will be 95% reliable. it also gives details of eight fires where the injured operatives were close enough to suffer burns. sprinklers are unlikely to be as effective in preventing injuries or fatalities in the incidents involving rapidly growing fires. They are usually not credited with improving life-safety. none of the incident descriptions discussed the use of directed systems and no conclusions can be drawn regarding their effectiveness.incidents where active safety measures are mentioned possibly reflects the fact that the majority of buildings do not have active fire protection (with the exception of fire alarm systems). Smoke detection The incident data shows that automatic fire detection is also effective. that it generally fails to provide water in 5% of demands on the system. The Australian Fire Protection Association publication ‘Fire’ [9]. when operators are in immediate proximity. However. when the workers are in close proximity. While general area sprinkler or deluge systems are not usually credited with improving lifesafety. Sprinkler systems. the only requirement for an active fire safety measure is an adequate fire alarm system. However. In each of the three incidents where detection was identified. the sprinkler system failed to operate. which. in comparison to an unsprinklered department store. sprinklers will extend the available evacuation time by a factor of eight. Water-based suppression systems In the five incidents where sprinkler systems are reported as being activated. its storage configuration and the design of the suppression system. but it was believed that it had been tampered with. 11 . It can also help reduce the effects of the fire by alerting the fire brigade at an early stage. However. these tend to be used in specialist high value applications such as clean rooms. potentially even before flaming. However. Such ‘directed systems’ include deluge or sprays protecting a single vessel. other more directed water-based systems are generally considered to be more effective in protecting people from the immediate effects of a fire. i. For premises that currently require a Fire Certificate. and. nor that life safety will be benefited in 95% of fires. four systems were effective in controlling the fire. or general area deluge systems. The data on automatic fire detection reliability given in DD240 [7] is that a properly maintained system will be 90 % reliable.e. In the fifth incident. are designed to limit the extent of fires and ensure that relatively small fires do not develop into major incidents.
Petrol ignited by static from unearthed bucket in process area where static precautions had been taken. Pouring action of powder led to static discharge into tank containing solvents. and use of suitable containers is an important mitigating measure.2 Incidents where static caused ignition 12 . Elimination of electrostatic charge Elimination of electrostatic charge is another preventative measure and. Nine incidents were reported where ignition was attributed to an electrostatic source . which exacerbated the seriousness of the incident. there were eight incidents where the importance of adequate containment. Cleaning rag soaked in petrol ignited by static spark. Containment In none of the incidents was it reported that containment in the form of compartment walls or bunds helped to limit the effects of fire. and therefore it is difficult to assess its effectiveness from the data. 3.static additive used in process.2. 55 74 82 93 Chemical Manufacturing Chemical Manufacturing FB(IV)* Chemical * Fire Brigade incident Table 3. 17 25 38 48 Industry type Chemical Manufacturing chemical Printing Description Toluene vapours ignited during cleaning operations by spark from unearthed bucket. earthing strap available. its successful implementation cannot be determined from incident reports. Firm was reluctant to change procedures. when effective. a key risk parameter. in the form of suitable containers for transportation of flammable liquids. In contrast.4 Fire prevention measures Hazardous equipment zoning Hazardous equipment zoning is a preventative measure. but not used. based on ionisation or optical detectors. Solvent ignited by static eliminator bar on conveyor belt. as the contents overflowed. as above. a fire detection system is defined as a conventional point detector. despite precautions of worker wearing anti –static clothing and anti. Solvent ignited by static during cleaning operation from unbonded container in area. Toluene and metal filing mix ignited by static when plastic lid of container opened. Propane ignited by static discharge.for the purpose of this study. allowing the fire to spread. The way in which small quantities of flammable liquids are transported is. Unsuitable containers significantly increase the risk. Solvent being decanted from metal into plastic drum and static led to ignition. Operation took place outside a properly ventilated booth. Operation took place in room with flame proof motors. The presence of bunds was identified in two of the chemical incidents. serious incidents are prevented and are not reported. rather than within it. as detailed in Table 3. Four incidents occurred for which the use of flammable liquids in nonzoned areas probably led to ignition. Rectified by the addition of earthed metal shute. but these were failures to implement the measure rather than a failure of the measure itself. because. was highlighted. but they were not effective. All eight incidents involved solvents or highly flammable liquids in unsuitable open top containers. HSE No. therefore.
These incidents highlight that.) However. These incidents were not malicious in intent. Therefore security and supervision are considered to be important mitigating measures. All of these incidents occurred when hot processes (welding and foundry operations) were being undertaken and the need for appropriate protection should have been obvious. where the fire involves hazardous materials and where the incidents are reportable under RIDDOR. Personal protective equipment There were five incidents in which operatives suffered injuries because they were not wearing appropriate protective equipment. for example. although warehouses are still vulnerable to arson attacks. when assessing their potential effectiveness it is necessary also to take into consideration the level of staff training and the procedures in place to make sure the precautions are implemented.000) where deliberate actions were seen to be the cause of 40% of fires [5]. residential. whilst static precautions are important preventative measures. it is still considered that the FPA data show that arson is likely to be a more significant risk than identified from the incident review. Therefore. The FPA data is for all major fires and would include industrial. The differences between the FPA data and the incident review may be partially due to the different nature of the incidents and how they are reported. The HSE incident data on the other hand is limited in the main to workplaces where HSE is the enforcing authority. institutional and educational establishments. lack of maintenance was the main factor in the fire occurring. although the latter may also relate to permit-to-work system failure. Maintenance and housekeeping In fourteen of the incidents (10% of the total data) the lack of maintenance. Examples of poor maintenance are allowing the damaged lagging of a vessel to become soaked with flammable liquid and failure to remove flammable residues from equipment. Three further incidents were the result of horseplay. (Note that it cannot be ascertained from the incident descriptions whether training. This contrasts strongly with the Fire Protection Association (FPA) analysis of large fire losses (over £50. the incidents still showed that when hot processes are undertaken. or housekeeping was a contributory factor. Permit-to-work Permit-to-work featured in 5% of the incidents reviewed. Security and supervision One surprising result of the analysis of the incidents was that arson was reported as the suspected cause of ignition in only one incident. especially. In four other incidents poor housekeeping allowed combustibles to build up and exacerbated the effect of fire when ignition occurred. the elimination of all sources of static is difficult to achieve. It is possible that many of these workplaces will have better security than the above establishments. rather than equipment not being provided. unless strictly controlled. The fact that the operatives did not use such protection may equally have been due to over familiarity. A lack of awareness of the risks in both the staff and the management was demonstrated in several of the incidents. Four of the seven incidents listed in the table below involved failure in permit-to-work systems or their enforcement. These incidents highlight the importance of effective maintenance and housekeeping as preventative measures. In the majority of these 14 incidents. supervision and/or permit-to-work systems were in operation or effective. However. but possibly resulted from lack of training or supervision. in the case of chemical plants. the use of appropriate personal protective equipment is an important preventative measure. a warehouse fire. wholesale/retail. In the 13 .
HSE number 65 Item ignited Solvent Cause Ignited when contractor under permit to work was welding nearby. Sparks from grinder ignited debris in bund. 79 40 Acetone vapour Gas 21 Butane Table 3. Correct implementation of permit-to-work systems is effective in reducing the likelihood of incidents.3 Incidents involving hotwork 3. manufacturing and garages being identified as premises where the risk is high. with smaller companies giving only a slightly greater risk. Considered in risk assessment but operator claimed not trained. but checks were not carried out. Failure of permit-to-work systems is a critical factor in risk of injury or fatality. Production plant was carrying out trials for use of mains gas instead of butane and had to flush out pipes. the way in which it is handled will be the most significant factor in determining the risk. Ignited by sparks during maintenance. Complete failure of PTW system.5 Key risk parameters and industries For the type of premises where a risk due to flammable materials is critical. The type of premises has a greater influence. as contractor had acted on his own initiative. although one case involved failure to control contractors adequately (Incident number86). control of ignition sources and good housekeeping and maintenance are key risk reduction 14 . the basic precautions are the most important. Once the premises has been identified as using flammable substances. or their consequences should they occur. but flame arrester ensured no one was injured. As with all areas of fire safety. Fire was small but operator received burns. Contractor removing lagging from storage tank. as those undertaking repairs or maintenance are necessarily close to the fire origin. However. In addition the emergency procedures that were implemented ensured that the effects of the fire were minimised. 94 86 Compound / Hexane vapours Vapours were ignited when welder who was fitting lids started to work with out a permit to work and ignoring a nearby ‘NO SPARKS’ sign. incident did highlight that company did not have sufficient procedures to control work of sub contractors. but presence of trained fire fighter ensured that local fire brigade was quickly summoned before fire developed into major incident. Welder carrying out work above gas supply pipe and it is believed that heat caused valve to rupture leading to fire. The use of correctly lidded containers. 34 Flammable liquids Debris Ignited by sparks when cutting up steel cage close to pit to collect residues. the size of the company is considered to be a minor factor. No PTW in place. However. or risk assessment carried out. Permit to work not considered to be at fault. PTW specified that fire protection should be provided to pipe. Comments Vacuum dryer from which residues leaked was thought to be empty. with chemical. No permit to work or risk assessment carried out. the incident data and statistics show that the use of flammable liquids is the overwhelming factor in determining the risk of fire and injury.others. Not a failure of the permit to work system. foundries. permit-work-systems were shown to be effective. contrary to guidance for this type of work.
However. or lack of awareness of. 15 .some possibly involving deliberate ignition (other than arson). these hazards . Fire protection measures have an important role to play in preventing small fires from developing into major conflagrations and potential disasters. for example brightening of fires with solvents and some of those resulting from smoking and horseplay. they are less likely to be effective in protecting occupants who are in close proximity to a fire involving flammable substances. Good training and awareness of the hazards associated with flammable substances are also important. A significant number of the incidents were partially the result of a casual attitude to.measures.
flame cutting and allied processes. 1997. HS(G)158. 16 . BS 5908: 1990: Code of practice for fire precautions in the chemical and allied industries. such as HS(G)158 on flame arresters. industrial.4. The safe use of compressed gases in welding. 2. Safe use and storage of cellular plastics. 1991 6. 4. Appendix C summarises the guidance provided by these documents and its effectiveness is assessed in Section 5. 2.1 UK FIRE SAFETY GUIDANCE Background The list of documents within this section is not intended to be comprehensive and there are other guides that are relevant to flammable substances in the work place. 8. 5. storage and other buildings. HSE Books. HSE Books. Energetic and spontaneously combustible substances identification and safe handling. 1994. 1998.3 HSE documents The following HSE guides were chosen as being those which building users should be following to determine what precautions they should be taking with respect to flammable substances. 2000.2 British Standards and building codes 1. BS EN60079: 1996: Electrical apparatus for explosive gas atmospheres Items 1 and 2 were chosen as being the key documents against which buildings are designed. 4. In general. 4. HS(G)92. Safe handling of combustible dusts: Precautions against explosions. 4. etc. The Building Regulations. Flame arresters: Preventing the spread of fires and explosions in equipment that contains flammable gases and vapours. HSE Books. A summary of the guidance provided in each code is given in Appendix C. The guidance in BS 5908 is broadly based and overviews the issues that are relevant to dealing with flammable substances in the chemical industries. The documents were selected on the basis that they provide guidance on the main issues associated with the flammable substances considered in the study. guidance dealing with detailed specification of fire protection measures and equipment has not been included. were included when the data review identified incidents specifically relating to implementation or failure of these measures. HSE Books. HSE Books. HS(G)140. HS(G)131. HSE Books. 3. Approved Document B: Fire Safety. HS(G)51. The spraying of flammable liquids. 1. The guidance contained within them on flammable substances is limited. They are fairly detailed and it is anticipated that they would tend to be used at management level to determine the need for preventative measures. 1996. 4. The safe use and handling of flammable liquids. 1998. offices. BS EN60079 is specific to the issues of flammable substances and provides detailed advice on suitable equipment selection and zoning classification. 1996. 3. HS(G)103. The storage of flammable liquids in containers. 1996. with the emphasis being on limiting travel distances in places of special fire risk and enclosing high risk items in fire resistant construction. 7. HS(G)139. HS(G)178. Some guides dealing with specific measures. HSE Books. HSE Books. BS 5588: Part 11: 1994: Code of practice for shops.
2000. Area Classification Code for Petroleum Installations. Model code of safe practice for the petroleum industry Part 1. INDG 227. INDG 297. Non-dyestuff chemicals: Safe handling in textile finishing. and in some cases provide guidance on fire safety issues that is not covered elsewhere. ISBN 0-7176-1786-6. such as the BAMA guide on aerosols. LPGas Association – Code of Practice 1. Institute of Petroleum. Solvent safety in printing. HS(G)64. 1st Edition. Electrical safety Code. INDG 308. 1990. The complete idiot’s guide to CHIP. 1991. Safe working with flammable substances. 4. 4. Safety in gas welding cutting and similar processes. INDG 331. Part 1: Design.9. their effectiveness has been assessed in Section 5. 2. Institute of Petroleum. Model code of safe practice for the petroleum industry Part 15. The storage of flammable liquids in tanks. 1. HSE Books. Safe use of petrol in garages. Third Edition. 6. 17 . Where applicable. It is anticipated that they would be the type of material used by firms to educate their workforces. 8. 4. 1998. 2. TIS 2. BAMA. 5. 1998. 6th Edition (7th Edition in preparation). HS(G)176. (Note that this document is no longer on sale but its key contents are broadly covered by: Fire precautions in the clothing and textiles industry.4 HSE leaflets The leaflets listed below are freely available from the HSE bookshop and can be printed directly from their web site. INDG 181.) 4. IAC/L85. 7. The guidance provided by the leaflets is summarised in Appendix C and its effectiveness is assessed in Section 5. installation and operation of vessels located above ground. 3. 3. Bulk LPG Storage at fixed installations. Working safely with solvents. 10. Assessment of fire hazards from solid materials and the precautions required for their safe storage and use. Textile Industry Advisory Committee. The safe use of gas cylinders. A Guide to Safety in Aerosol Manufacture. INDG 273.5 Others The following guides have been selected as being those that are in common use within the industry. 1999. 1.
2. but risk assessment inadequate. and solids. 3 15 16 48 Item ignited Cleaning solvent Solvent Petrol Solvent Cause Nearby worker using angle grinder. unless it was obvious from the descriptions that they were not HFLs.3). Operator sprayed inside of bins and ignited to clean off residues Deliberate ignition but unsafe practice. or was due to an omission in guidance. but company argued industry wide practice. because of the specific guidance available for fire hazards in both these types of premises. Deliberately being burned off filter for cleaning Apprentice burning off solvents. Operator suffered 40% burns. gases. or was the type of accident that is difficult to avoid without the benefit of hindsight. as HFL solvent in open can. Instructions on washer stated not suitable for use with HFL. The garage and chemical industry incidents were considered separately (in Sections 5. Company to write stricter procedures.2 and 5. Have spent £200. Note that 86 incidents out of the total of 135 incidents identified (see Section 2) provide sufficient information to make a judgement regarding effectiveness of guidance. Solvent carried in open top drum. Comments Minor injuries.1. Static caused ignition when ink was being decanted. Company have now revised procedures to minimise liquid containers. The objective was to attempt to determine whether the incident occurred because guidance was not followed.1 EFFECTIVENESS OF UK GUIDANCE Structure of review The information derived from the incident review has been compared with the relevant guidance. Major burns. Flash fire resulted in burns. Minor burn to hands. Operative using petrol to clean off tools. Solvent being used in parts washer ignited. incidents where the material ignited was named as a solvent were placed in the highly flammable liquid (HFL) category.3. 5. Alcohol used to burn mould coating off to reduce risk of explosion. This exercise was undertaken for each type of flammable substance considered in the study and as defined in Section 3. Worker added more alcohol without realising mould already ignited leading to flash fire.3. Employee injured.1. As noted in Section 3. Sparks ignited the solvent which flashed back to the container. 5. 52 56 Solvent Clothing soaked in solvent HFL solvent Clothing and solvent Frescote 100 & Isoprop alcohol 59 61 63 18 .1 Analysis of fire incidents by substance type Highly Flammable Liquids (HFLs) HSE No.000 rectifying situation. Firm was aware of dangers of static. separation of larger containers and procedures for inspecting mould for flames. These 86 incidents are included in the tables given in Sections 5. Procedure was to use diesel. that is: highly flammable liquids. flammable liquids.2 5. Unsafe working practice Minor injuries. Minor injuries. Operator suffered minor burns while acting completely against procedures.5.3. HSE inspector made particular reference to guide.
HSE No. 64
Item ignited Acetone
Cause Acetone used for cleaning dying machine. Build up of flammable atmosphere leading to ignition. Ignited when contractor under permit to work was welding nearby.
Comments Operator suffered major injuries. Liquid not properly contained, multiple ignition sources and no risk assessment. Vacuum dryer from which residues leaked was thought to be empty. Reasonable assumption and permit to work not at fault. No casualties and emergency procedures for dealing with fire worked well. No one hurt and plant evacuated as a matter of safety. Old plant firm already committed to major reinvestments. Operator suffered minor burns. Operator suffered serious burns. Incident did highlight a lack of awareness of risks. Operator suffered major burns to hand. Poor working practices. Solvent was used as replacement for trichloroethane. No PTW in place, or risk assessment carried out. Operator occasionally helped out around spraying shop. Minor burns. Protective clothing not worn as possible to do this operation remotely. Procedures being changed to prevent re-occurrence. Operator suffered major burns before fire was extinguished.
Overflow of solvent to drainage system followed a small solvent fire caused by bearing fire on motor. Container was knocked over and ignited by switch. Operator mended leaking filter and clothing was soaked. During break set light to himself twice. The second time suffered serious burns. Used to wipe conveyor belt down to prevent static build up. Solvent ignited by anti–static bar. Ignited by sparks during maintenance. Operator using waste contents of paint shop to brighten fire. Drum exploded killing operator. Process was to burn solvent off when dressing top. Operator was undertaking a routine cleaning operation between paint colours. Carrying solvent in open top can ignited probably by spark and flashed back to can.
IP alcohol Ethanol
Solvent with flash point of 20oC Acetone vapour HFL HFL
Solvent with flash point below 16oC
Fire Brigade Incidents FB(IV) Petrol Worker was using petrol soaked rag to clean machinery. Static spark ignited employees overalls.
Unsafe working practices led to minor burns.
Table 5.1 HFL and Solvent Incidents The use of solvents, and HFLs is covered by the guide ‘The safe use and handling of flammable liquids’, HSG 140, and two leaflets ‘Working safely with solvents’, INDG 273, and ‘Safe working with flammable substances’, INDG 227. Petrol incidents that have occurred in garages have been considered separately in Section 5.3.1, because of the specific HSE guidance provided. In 16 out of the 20 incidents, HSE guidance was not followed. Solvents were not transported in suitably lidded containers and the need for good ventilation was ignored. In three of the incidents the operatives were acting directly against either the equipment suppliers’ advice, or company procedures. In one of the most tragic incidents, HSE number 80, the operative was using a HFL to brighten a fire and was subsequently killed. All of these incidents
highlight the casual nature with which these potentially dangerous substances are sometimes treated, due to an apparent lack of understanding of the potential risks, or over familiarity. The four other incidents (HSE numbers 3, 65, 68 and 72) appeared not to be due to failure to follow guidance and the incident involving solvent overflow, HSE number 68, is an example of where good procedures minimised the consequences of a fire. The guide HS(G)140 and leaflets on flammable liquids make clear the dangers of using solvent. The leaflet on safe working with flammable substances (INDG 227) uses the VICES principles (see Appendix C, Section C.3.6) to summarise adequate precautions relating to Ventilation, Ignition, Containment, Exchange and Separation. The ‘Exchange’ precaution relates to exchanging flammable substances for less flammable, or eliminating flammable substances altogether. However, from the incident data it is clear that companies are still using flammable substances with flash points below normal room temperature. In incident HSE number 93, a solvent with a flash point of 13oC was being used for a routine cleaning operation. In one of the fire brigade reports on a major firm, Fire Brigade number FB(IV), procedures involved the use of petrol to clean machinery. Given the large number of solvent fires, the HSE leaflet on ‘Working safely with solvents’ (INDG 273) could be more explicit on the dangers of fire. In an A4 folded leaflet the advice on dangers of fire are given in a small section and only in terms of the hazards presented by toxic gases produced by chlorinated solvents. It would benefit from a larger section dedicated to the potential fire hazards and the fire safety issues. It would also be useful if it pointed the user to the guide on ‘The safe use and handling of flammable liquids’, HS(G)140. Improving the clarity of guidance in the leaflet may help, but the nature of the incidents shows that the problem tends to be due to either ignorance of the dangers, or a casual attitude to the hazards of working with solvents and HFL, rather than the quality of guidance available. These problems associated with working with flammable liquids were highlighted in the HSE’s own review of the 1994/95 and 1995/96 fire statistics [10]. Therefore, improving the understanding of the issues associated with handling flammable liquids, and tackling the disregard for the potentially fatal consequences, remain the main issues to be addressed. 5.2.2 Flammable Liquids
HSE No 27 Item ignited Oil Cause Fire occurred when oil lines for turbine ruptured due to excessive vibration from turbine due to blade cracking. Ignited by sparks when cutting up steel cage close to pit to collect residues. Ink residue ignited probably due to friction Overflow of tank leading to ignition by electric motor. Ignited in roll mill. Residue of oil ignited when oxyacetylene torch played on it. Ignited in pump, probably by friction. 20 Comments No casualties and unusual failure.
34 39 41 45 75
Flammable liquids Ink residues IPA alcohol and water Oil mist Oil
Considered in risk assessment but operator claimed not trained. Strict cleaning regime implemented and detectors added. £20 million pounds of damage, but no casualties. External mixing tank installed. Sprinkler system successfully put out fire. Cylinders normally disposed of whole, but too large to move. Company changed procedures to avoid re-occurrence. Automatic alarm initiated and suppression system operated.
HSE No 90
Item ignited Oil
Cause Rupture in pipes caused hot oil to spray on adjacent furnace and ignite. Cause was incorrect close down procedure that allowed the pipes to be filled with oil on start up. Frozen oil was being warmed using torch on low setting. Oil sprayed out of bleed screws that had been undone to prevent pipes rupturing.
Comments No injuries. Company have revised their procedures.
Dowtherm heating oil
Set supervisors clothing alight. Suffered burns. Goggles prevented eye damage, but no face shield or gloves. Permit to work system was not used, because job considered too small.
Table 5.2 Flammable Liquid Incidents The use of flammable liquids is covered by the guide ‘The safe use and handling of flammable liquids’, HS(G)140, and the leaflet ‘Safe working with flammable substances’, INDG 227. The incidents in Table 5.2 involve liquids which have a flash point of greater than 32oC (see definition of flammable liquids in Section 3.1.3) and these incidents provide a useful comparison with those involving the more volatile solvents and HFLs. There are notably fewer injuries, reflecting that they are less easily ignited, although this could partially be due to the majority of incidents involving machine failures with occupants not being in the immediate vicinity. The incidents involving machine failures highlight the importance of good maintenance and the need to follow procedures. However, their occurrence cannot be attributed to a failure to follow specific guidance. It is also worth noting that in two incidents, HSE numbers 45 and 87, suppression systems were provided and were completely effective. 5.2.3 Gases
HSE No 1 Item ignited Silane gas Cause A problem developed in the process and it was decided to pump gas out as per the procedures. A fire developed in the duct. Furnace blow back when attempting to re-light. Operator suffered flash burns when attempting to light steel furnace. Hot bolt fell on hose. Production plant was carrying out trials for use of mains gas instead of butane and had to flush out pipes. No permit to work or risk assessment carried out. Operator suffered major burns when fire ball emerged from furnace. Knew there was a problem when flame went out, but could not move away quickly enough. Comments No injuries.
2 18 20 21
Furnace gas Furnace gas Oxy/propane Butane
Minor burns. New procedures and flame failure device provided. No protective clothing worn and side holes were not used. Change in procedures. This ignited gas leading to serious burns. Fire was small but operator received burns. Complete failure of PTW system.
Furnace recently relined and door not correctly fastened, leaving sufficient air gap for flow of fumes, and causing a build up of unburnt gases.
cylinder was not blown down prior to mounting on rig and procedures were not followed that led to labelling of empty cylinders. 18. Supervisor advised of need to ensure equipment is maintained. HSE number 18. but gas shut -off valve avoided injury. Operator used gas cylinder as step up snapping regulator and releasing propane which ignited engulfing him leading to death. Trainee opened regulator and it exploded causing facial burns. There are eight information sheets and four foundry leaflets listed on the HSE web site. adequate personal protective equipment. 49 Propane 66 Oxygen (not flammable but increases fire hazard) Oxy acetylene 92 Numerous faults in procedures. but this had not been checked. Incorrectly disconnected gas pipe causing 7 second release. Defective flashback arrestor allowed gas from split hose to be ignited. The contents of a full cylinder was ignited when being devalved on rig. failure to wear personal protective equipment contributed to the severity of the injuries. In one of the incidents. Fire Brigade Incidents FB(II) FB(VIII) Acetylene LPG Table 5. Therefore this is an area where specific guidance on fire safety could be beneficial.3 Gas Incidents Guidance that is specific to the safe use of gas is given in the HSE leaflet ‘The safe use of gas cylinders’. Incident revealed shortfalls in application of permit to work systems. Hot work being carried out above gas pipe. Ruptured pipe led to leak of LPG.3 involve furnace gases (HSE numbers 2. Valve fitted with flame arrester and no injuries. Tragic incident caused by incorrect use of equipment. Comments No clear cause of fire as operative wore correct anti–static clothing. and various industry codes such as those issued by the LPGas Association and the British Compressed Gases Association. etc. but was added during two week monitoring period. Part of the regulator was missing. Acetylene gas ignited because of defective valve. but none of these contain specific guidance on fire safety. Four out of the fifteen incidents in Table 5. Work undertaken in a pit. 24 and 33). Foundries contain high temperature equipment and possibly naked flames and are environments where there are the general health and safety requirements of ensuring safe working practices. Heat believed to cause valve to rupture causing leak. Minor injuries Minor burns. No injuries. INDG 308. Gas pipe was not protected against effects of heat. Operator disconnecting gas and air pipes to furnace.HSE No 25 Item ignited Propane gas 33 Furnace gas 35 40 Gas Gas Cause Injected in to extrusion machine for polyurethane. Failure in procedures. When waste was cleared appeared that static ignited accumulated gases leading to minor injuries. 22 . Despite rocketing around workplace no injuries. Pressure drop caused shut off valve to operate. Permit to work stated need for fire protection. Anti –static additive was not found in material tested. HSE(G)158 on ‘Flame arresters’ which deals with specific equipment issues.
Electrical systems were not suitable for use in flammable environment. Poor maintenance. No injuries. 70 71 Paint residues GRP HSE recommended better cleaning procedures. Ignited when in contact with heating element. Fire spread when conveyor belt and guarding was ignited.4 Solids HSE No 6 7 28 32 42 50 Item ignited Linoleum Sugar waste Burning bread dough Cardboard slip sheet Wax Resin trapped in lagging Cause Friction in mill caused fire. there may be scope for simpler leaflet. although small fires occurred. No injuries. No injuries. Second incident. Poor working procedures. Ignited in duct. Failure in procedure to check that kettle was not already heated. No injuries. In two incidents (HSE numbers 35 and 92). 77 81 Paint powder Lint 91 Wax . Employee carelessness rather than failure in procedures. No injuries. guidance was being followed and there were minimal consequences. Given the type of incidents. It appears to be aimed at fulfilling a dual role of providing a user-friendly guide for workers with its humorous tone. Cause unidentified. Spray booth 70 % destroyed. peroxides. running to 16 pages. Have introduced better cleaning procedure. An interesting aspect of the guidance on the safe use of gas cylinders (INDG 308) is that the leaflet is more detailed than others. but again the incident was a direct result of failing to follow procedures. In both incidents involving gases as part of the production processes. The fifth incident. which ideally would be no more than two sided on an A4 folded sheet. HSE reference 20. Ignited by UV dryer on production line lead to door lacquer igniting. HSE reference 40. HSE numbers 1 and 25. HSE reference 66. Suppression system considered. the gas equipment had not been properly maintained.2. No injuries but factory destroyed. 5. Faulty fan on coal fire drying plant caused fire to spread. Ignited when spring fell causing short circuit and sparks. Fault noted and planned to rectify at next shut down. Left on unattended heating appliance led to fire and destroyed building. the welding operative had failed to take sufficient precautions in working overhead.Five of the eleven other incidents involving gases can be attributed to failing to follow HSE guidance. Overheated and ignited when 10 litres was poured into kettle. LPG cylinders. In another. whilst at the same time providing a higher level of detail for employers. Lagging had become progressively damaged by loading practices. was more unusual in that it occurred during the servicing of cylinders. Inadequate fire precautions and fire fighting equipment. but plant contained large quantities of resin. and in another. Example of poor housekeeping and unsafe practices and inadequate precautions such as suitably zoned motors. 23 Comments Building destroyed but no injuries. including the one in which a trainee was hurt. the operator had not shielded a gas pipe in direct contradiction to the working permit.
HS(G)64 is the most applicable guide as it deals with fire hazards from all solids. INDG 331. the nature of fire growth in solids is different to that in liquid and gas fires. There were also large quantities of flammable liquids and gas bottles distributed around the factory. HS(G)64. controlling ignition. Safe handling of combustible dusts: Precautions against explosions. Comments Minor injury Serious injury. HS(G)92. Despite this there is more guidance available for dealing with this type of fire than for liquids or gases. see section 4. 5. the life safety threat is rarely immediate. etc.4 Solids Incidents The guidance relating to solids is given in several documents: · · · Safe use and storage of cellular plastics.1 Analysis of fire incidents by workplace Garages The guidance specific to garages is the one page HSE leaflet ‘Safe use of petrol in garages’. Despite the building being completely destroyed there were no casualties. the low number of injuries could indicate that the guidance for dealing with the hazards of solid fires is effective. There is normally some time to escape before the fire has grown to a sufficient size to cause conditions within the room. gives the method for determining high risk solid materials. Of course. Hse no.3 5. The recommendations it gives are based on good fire safety practices of compartmentation. Operator investigated with halogen lamp. which can immediately engulf occupants. Comments Operator burned. housekeeping. The exception to this is when solids are in powder form. fires involving flammable solids represent a minor risk in comparison with liquids and gases. Shavings suddenly expelled and ignited. HS(G)103. 24 . Welding. For example. The one incident where this was clearly not followed was in HSE number 71.3. Assessment of fire hazards from solid materials and the precautions required for their safe storage and use. or building. flame cutting and allied processes’ applies when hot work is being undertaken. More generally.HSE No 96 Item ignited Wood shavings Cause Machine became blocked. unless it is in a confined space or the occupants cannot escape. In fact. However. which can lead to explosions. HS(G)64 (now replaced. 8 12 14 Item ignited Petrol Petrol Plastic trim Cause Unknown Fuel line disconnected when engine running. A notable feature of the incidents involving solids is that there were few injuries. Table 5. Risk assessment inadequate as only considered arc-eye. Minor injuries. Few of the incidents above can be considered to result from a failure to follow appropriate guidance. Even when rapid growth of fire occurs in solid material. although now replaced. Company revised procedures to use only low voltage fluorescent lamps in this area. the guide HS(G)139 ‘Welding. but it is not clear where this is actually being applied.3 (10)). From the incident review and the Home Office fire statistics. to become untenable. the review suggests that there may be scope to simplify it. The incident review provides no evidence that the guidance on fires involving solid materials is not being applied.
Two of the petrol incidents. Risk assessment was inadequate. HSE reference 95 and 12. Serious building damage. 83and 53. The problem of garages and draining petrol was highlighted in the HSE review of the 1994/95 and 1995/96 fire statistics [10]. Tank dropped as being removed ignited by broken lamp. Comments Employee injured. Directly against HSE guidance. prior to removal. Therefore this is another area where the key issue appears to be how to educate the work force to appreciate the potentially fatal hazards associated with petrol in the hope that they will then act accordingly.Hse no.2 Chemical Industry HSE No 5 Item ignited Solvent vapours Cause Vapours left in large tank when car underseal that contained a large quantity of solvents was emptied. Comments Operative suffered major burns. Fuel line removed when engine was running. Employee injured. were due to careless working practices of removing fuel lines with the engine running.5 Garage Incidents In the four incidents directly involving the draining of petrol tanks. Table 5. The two other petrol incidents. Ignition was caused by friction as bearing was designed to be lubricated by tank contents. 25 . they cannot be attributed to failure to follow HSE guidance. Half full tank dropped causing lamp to smash leading to spark and ignition. Proper draining equipment available. the operatives had not followed the guidance in HS(G)139. Petrol had been drained in pit. 29 30 31 43 51 53 83 88 95 Item ignited Oil/petrol Dust Petrol Petrol Petrol Petrol Petrol fumes Oily rags Petrol Cause Oil had been contaminated by petrol. HSE references 14 and 88. Over heating motor spray booth. but unknown operative had used bucket. Leaked onto a sender unit. but not why. There is not a problem with the guidance as it is both concise and explicit. No injuries. No safe working procedures. HSE references 31. as they had not removed or shielded any combustibles in the immediate vicinity. HSE reference 43 and 8. Ignited combustibles when warming components No receptacle to collect petrol.3. Possibly ignited by cigarette as tank being drained. HSE guidance was not followed. In both hot work incidents. 5. 51. This caused the garage to become filled with petrol fumes. were caused by leaks and their cause is unclear. which were subsequently ignited. However. Ignition sources were not kept clear and the need for adequate ventilation was not considered. where an operative had not used a proper receptacle. Two dead and two critically injured. can also be attributed to draining petrol tanks. Subsequently ignited when welding started. Mechanics had tried to drain tank by running engine. Minor injury and serious damage. Gas torch. Employee suffered severe burns. Employee injured. Experienced mechanic. He was aware that mixer should not run dry. Minor injuries. Fumes ignited by welding. HSE reference number 29. A fifth incident. One tank was actually drained in a pit and in none of the cases was draining carried out in the open air as recommended.
Example of failure to identify static hazard. Plant now obsolete. Toluene vapours ignited during cleaning operations by spark from unearthed bucket. killing them as a batch mixer ignited. Use of nitrogen was considered a poor decision. inadequate ventilation. No injuries and an example of successful fire protection as slugcatchcr was drenched with water and foam and controlled drainage completed. but had not appreciated thin film of catalyst would be left on the wall of the vessel and operation was carried out against procedures by allowing air in when it should have been conducted in inert nitrogen atmosphere. Probable cause deposit of palladium/ carbon. Major investigations identified complete lack of controls on ignition. Was released into atmosphere when rubber hose became detached and ignited. but no injuries and incident was well managed. Slugcatcher being purged with nitrogen as inadequate water supplies. One operative suffered serious burns. Company had carried out risk assessment. Poor system of work for the use of these materials. Sanotherm heat transfer oil ignited when leaked above its flash point during draining operations. Fire occurred when funnel being used to fill vessel with chlorinated paraffin. but a large amount of damage caused. 54 Hydrogen 55 Petrol fumes Some plant damage.HSE No 10 Item ignited Two products (type/grade numbers) Organic peroxide Toluene Tool oil 11 17 19 Cause When allowed to dry out these items become mixed. Minor injuries. forming a percussive and shock sensitive compound. Trichloroethylene degreasing tank boiled dry initiating alarm and fire brigade attendance.product of chlorine production. Sprinklers operated and were effective against ensuing fire. Static caused by pouring action from polythene bag. with man made outer cover. 22 Pyrophoric residues 23 26 HFL Catalyst residue 36 37 Trichloroethylene Butane Fire engulfed two workers. Worker suffered minor injuries. Company has subsequently reviewed its procedures. Probable cause build up of static on bucket. Gases from butane cylinder ignited when being changed. Pyrophoric residues on mist extractor ignited. Subsequent investigation identified deficiencies in maintenance and risk assessments. No injuries. Fire in recovery plant that separated organic peroxide from aqueous solution. Inadequate temperature control and no fire fighting equipment. Firm to completely reassess risk assessments. 26 . Remedial action of earthed funnel added for filling operation. Fumes ignited as worker was filling process vessel with metal bucket. Subsequent risk assessment to consider where else PR residues could build up. Example of fire detection working effectively. Operator burned. 38 Acetone and toluene vapours No injuries. No injuries. Produced as a by. Comments Operative suffered extensive burns. actions were against training and procedures to change cylinders in open air. Despite 10 years experience of operative. with plant completely destroyed.
the chemical industry is better able to cope with the consequences. In one of the three incidents in which inadequate precautions were taken to avoid static. Therefore. but no injuries. where two workers died. Large scale fire. Comments No one hurt. The incident data also demonstrate that. Where flammable liquids and solvents were being used. the firm understood the risks. but were reluctant to change the procedure. However. incident did highlight that company did not have sufficient procedures to control work of sub contractors. contrary to guidance for this type of work. HSE number 82 (the other two incidents were HSE numbers 17 and 38). The IP Guide 15 on Hazardous Area Classification is also relevant. but presence of trained fire fighter ensured that local fire brigade was quickly summoned before fire developed into major incident. and two leaflets ‘Working safely with solvents’. The relatively high number of incidents must be partially attributable to flammable substances being commonly used in this industry. The chemical industry generally performs well in the incidents reviewed. HS(G)140. Old plant and firm already committed to major reinvestments. 27 . as contractor had acted on his own initiative. provides broad guidance on fire safety. The safe use and handling of flammable liquids’. 94 Debris Table 5. significantly more than in the other industries. Mixed with metal filings to form friction material. would apply. Production trials carried out under lab conditions. HSE number 23. there is little evidence of the casual attitude to the use of flammable liquids. Electrics were flameproof. but large quantities of flammable liquids in heated rooms. Not a failure of the permit to work system. which is evident in other industries. INDG 273.HSE No 68 Item ignited Solvent 76 82 Ink pastes Toluene 86 Compound / Hexane vapours Cause Overflow of solvent to drainage system followed by a small solvent fire caused by bearing fire on motor. Vapours were ignited when welder who was fitting lids started to work with out a permit to work and ignoring a nearby ‘ NO SPARKS’ sign. Contractor removing lagging from storage tank.6 Chemical Industry Incidents The BS 5908 Code of practice for fire precautions in the chemical and allied industries. occurred in a small firm and does not appear to be representative of the industry as a whole. once an incident occurs. However. the incident review has not shown that the guidance for the chemical industry is inadequate. and ’Safe working with flammable substances’. Plant evacuated as a matter of safety. because it could effect their experimental production process. The one exception. Small flash fire as operator opened bin caused by static. Cause of fire not identified. INDG 227. Sparks from grinder ignited debris in bund. The role of fire protection and good working procedures is evident in approximately 50% of the incidents.
It would also be of use in assessing the relative importance of mitigation measures. and hence could be used to assess how current guidance relates to the control of fire hazards and to inform the development of future regulations and guidance. or combinations of mitigation measures. The analysis of incident data suggested that the presence and handling of highly flammable or flammable liquids (HFL/FLs) presented a significantly greater risk to workers than any other material. 6. Thus the risk assessment model is aimed at the immediate effects of a flammables incident. The model considers process fire precautions only. When using the model. the user will be required to rank various site attributes (e. Various hazard index methods are available for assessing risk. For this audience the model would need to be simple. However. those responsible for ensuring the safety of staff in the workplace. This is because in most incidents there is sufficient time for people not immediately adjacent to the fire source to escape. The simplest is the use of a ‘risk matrix’. with the model being an aid to workplace risk assessment and maximising the effect of any subsequent risk-reduction initiatives. types of material stored) and precautions (e.g. Therefore the risk assessment model being tested in this section has been developed for the workplace use of HFL/FLs. The first is on-site personnel.1 PROPOSAL FOR RISK ASSESSMENT METHOD Scope of method The previous sections have identified the key attributes of a workplace which contribute to the risk of injury or fatality from incidents involving flammable materials. Such methods require detailed input of scores relating to potential fire hazards and their mitigation. A further feature of the incident data is that most injuries or fatalities occur at the start of the incident. Two potential target audiences were identified for the proposed model. Thus introduction of mitigation measures can be targeted at those hazards which have a high level of severity and a high likelihood. These descriptions are provided in Appendix E. Various methods for risk assessment are currently used for industrial applications. within the workplace. and does not include general fire precautions as the latter are outside the scope of this study (see Section 1. i. all of which must be accounted for in any risk assessment model. including flammable gases.e. These scores are then used to define the fire and explosion risk and to identify equipment that is most likely to contribute to a fire incident. Such a method is qualitative and relies fully on the judgement and experience of the user. The structure of the model is based on event-tree modelling. but is semi-quantitative. since the incident data are insufficient to produce a fully quantitative model. or because precautions are in place to prevent the escalation of the incident. if proven. These criteria will comprise a set of descriptions. The value of the model to this group would be to identify high-risk workplaces or working practices. control of ignition sources) against a set of criteria.g. 28 .6. The second target audience is risk-analysts. The current form of the model assumes the latter target audience. ‘average’ or ‘poor’.1). The model framework is defined in Section 6. which rate implementation of each precaution as either ‘good’. The calculation of risk within these methods is often complex and the methods are most effective when used for assessing the risk within large industrial sites.2 and the development of the model is detailed in Appendix D. where hazards are ranked with respect to both their severity and their likelihood. for example Dow’s Fire and Explosion Index [11]. this does not imply that general fire precautions are not risk significant and although the incident data does not show significant casualty levels attributable to deficiencies in these precautions. and almost always to personnel involved in the initiation of the incident or else in the immediate vicinity of the fire. without specialist risk assessment experience being required for choice of input data or interpretation of results. this may be because they are already being implemented effectively. It considers immediate effects to workers and does not consider escalation of the incident. although it is of a style that could be adapted for other materials.
Similarly. storage tank etc. 6.) Severity of event (fuel type. such as separation or segregation of flammable materials.1. temperature of process Frequency of use Containment (lidded.2 Model framework The model considers three steps in an incident which lead to fatality or injury. such as provision of evacuation routes.) Proximity of personnel to event (room sizes. housekeeping etc. · · · · Determine probability that fuel vapour comes in contact with ignition source · · · · Type of fuel. the benefit of directed forms of water spray or deluge is also considered to be prevention of escalation. given that the release has occurred.4 discusses the potential use and benefit of the model to the target audience.) Other fuels around Toxic nature of fuels Storage pressurised bottles Detection and suppression systems Determine frequency with which fuel vapour is spilled / exposed Determine probability that someone is injured/killed by initial event · · · Determine probability that event escalates quickly to injure/kill others · · · · Figure 6. The risk is then a product of the release frequency.3. the probability that the flammable vapour comes into contact with an ignition source. and illustrates its use through a worked example based around a garage handling petrol. is estimated. maintenance and inspection.) Containment (lidded. Certain process fire precautions. flashpoint. guidance etc. Finally. Section 6. explosion. as illustrated in Figure 6. will mitigate against escalation of a fire event. occupancy. hazards introduced. rate of growth. and the conditional probability of injury. the probability that personnel are injured or killed by the ensuing fire or explosion is determined. the incident data reviewed in 29 . Thus it does not consider escalation of the event to other flammables (the fourth step shown in the figure in dashed boxes).e. storage tank etc) Control of use Quantity of fuel (size of vapour cloud) Location + quantity of ignition sources (sources attached to release source. Appendix F provides a step-by-step guide to the model input and calculations for this worked example. given that ignition has occurred. Once exposed. Most precautions that mitigate against injuries or fatalities occurring during escalation of an event will be general fire precautions. Each step depends on both the work conditions and process (i. the conditional probability of ignition. as discussed in Section 6. fire size etc. like hotwork etc. unlidded.1. operation etc. While it is possible that such systems may have some benefit in reducing immediate injuries or fatalities.) Precaution measures (security. In order for an incident to occur. the model developed in this study is aimed at the immediate effects of a flammable incident.The testing of the model is described in Section 6.) Precautions (work procedures.1 Structure of risk assessment model Note that. requirements for use of HFL/FLs) and precautions taken to reduce hazards. or combinations of these attributes. which illustrates the sensitivity of the predicted risk to the various workplace attributes. and is ignited. the flammable liquid must be spilled or exposed and the model considers the frequency with which this occurs.
The descriptions are given in Appendix E and are based on wording used in HSE leaflets.3 Model sensitivity The user is able to rate each of the workplace attributes A to N (see Table 6.1 Relationship between workplace attributes and calculation steps For each attribute. If the user sets all of the attributes to ‘average’ then the risk value given by the model is 1.1 lists the attributes of a workplace which are critical with respect to risk.Section 3 could not be used to confirm this (or otherwise) and it is assumed that the benefit of directed water spray or deluge systems is mainly in preventing escalation of the event. Attribute measured A B C D E F G H I J K L M N Material classification (flash point) Release quantity (container size. the user will set all attributes to ‘good’.) Control deliberate ignition (arson. Table 6. Where a box in the table is shaded. ventilation) Housekeeping (spill cleanup. as identified in Sections 2 to 5. that attribute is considered within the relevant calculation step. contractors) Maintenance and inspection (containers) Control fixed ignition sources (HAC. Attached to each rating of each attribute is a score that is entered into the risk model. regular or occasional) Containment (lidded. 6. The determination of the scores and the way that the score for each attribute affects the risk is detailed in Appendix D. occupancy) Frequency Ignition Injury Table 6. horseplay) Proximity of staff (operation. clothing control) Control misc. If all possible measures are taken to reduce the risk. if all attributes are rated as ‘poor’. This variation in risk is illustrated in Figure 6. ‘average’ or ‘poor’. ‘good’. which shows the variation in risk as a ratio of risk to average risk.2.2 also shows the effect of varying the ratings (i. unlidded or fixed tank) Spill control (bunding. then the risk increases to its maximum value of 2x102. Conversely.3x10-1.4x10-5. The table also illustrates the importance of each attribute to the three steps of release frequency. descriptions are provided in order to aid the rating of that attribute as either ‘good’. ‘average’ or ‘poor’) for attributes which affect the release frequency.e. room size.1) in the model as either ‘good’. friction etc. sources (lightning. probability of ignition and probability of injury or fatality. The results of the model appear to be reasonable in that they suggest that the greatest benefit will be derived from measures which mitigate against a release of flammable liquid 30 . and the risk will drop to its minimum value of 5. familiarity. ‘average’ or ‘poor’. noting that this is not an absolute value of risk as the frequency is based on a notional value of 30 releases per year . segregation) Control static ignition (design. the probability of ignition and the probability of injury. operation) Frequency of use (constant. Figure 6. enforcement) Staff awareness (training. removal waste) Safety management (procedures. The current version of the model described in this report does not consider the contribution of either general or process fire precautions to reducing the likelihood of event escalation or the ensuing effects on workers.
2 Variation in risk output for frequency. C. where the introduction of safe working procedures. These are safety measures built into the workplace. Such measures are only effective if enforced by the workplace management. which shows the effect on risk of each individual attribute.00E+03 Maximum risk Poor frequency control 1. It can be seen that each of the control of ignition source measures (J. as removing the flammable material from the workplace. These are controls on working practices. followed by measures which reduce the probability that someone is injured. Thus they include the siting of fixed ignition sources and provision of ventilation. which is aimed at incidents where personnel handling the flammable material. The figure also shows that management controls have a significant effect on risk. B. by using smaller quantities of a less flammable liquid). or setting up the operation such that the material is never exposed.3 shows that inherent attributes have the greatest effect on risk within the model. such as permit to work systems. ‘fixed mitigation measures’ and ‘management controls’. K and L). but in many cases they will be fixed. when varied from average. are most at risk. This is because the fixed mitigation measures relate mainly to the control of fixed ignition sources. or those introducing ignition sources such as hot work. For control of fixed ignition sources to be effective. I and M). It may be possible to change these attributes (e.00E+00 1. These are features of the process or operation being undertaken within the workplace. and whether these are followed by employees.occurring.00E+04 1. and which do not require adherence to work procedures to be effective. all ignition sources must be controlled and not just a fraction of them.00E-02 Good ignition control Good frequency control 1. J. H. Safety management (G) and staff awareness (H) have the greatest impact on risk. This is further illustrated in Table 6. are 31 . Figure 6. This is to be expected. will remove the risk and make other mitigation measures redundant. This reflects the nature of the hazards being assessed by the model.00E+01 1. 1.00E+02 Raio of risk to average risk Poor ignition control Poor injury control 1. The figure suggests that fixed mitigation measures have significantly less effect than inherent or management measures. L and M) has a small individual effect on risk. Fixed mitigation measures (E. which is consistent with the incident data. designed to mitigate against the occurrence and effects of fire. ignition and injury control Figure 6.00E-04 Figure 6.00E-03 Minimum risk 1.00E-01 Good injury control 1.2. D and N). G. Thus removing fixed ignition sources from the vicinity of a flammable material will not significantly reduce the likelihood of ignition unless work procedures are also in place to prevent hot work or deliberate ignition. followed by measures which reduce the probability of ignition of release. Management controls (F.g. as defined below: Inherent attributes (A. K.3 shows the sensitivity of risk (as output by the model) to workplace attributes grouped into those which are ‘inherent’.
Current guidance for a workplace or type of operation could be reviewed to ensure that it identifies the fire hazards which have the greatest contribution to risk.00E+03 Maximum risk 1.28 3.11 0.93 1.4 further discusses the use of the model in relation to a worked example for garages handling petrol.32 3.00 0. B.52 1.88 1.52 1.33 3.59 0.88 3.09 1.40 2.00 1.2 Potential variation in risk for individual workplace attributes Qualitatively.00E-03 Minimum risk 1.08 1. Potentially. 6. The mitigation 32 .18 Total variation (Poor/Good) 9.00E+01 Poor fixed measures 1. Table 6.96 1.24 0.25 0.04 0.00 3. Section 6. 1.00 2.43 14.33 0.87 0. fixed and management controls Ratio of risk to average risk Good Poor 0.key risk contributors.00 10.34 1.3 Variation in risk output for inherent.09 10.4 Model use The model can be used to rank workplaces with respect to fire risk (by comparing total risk levels between workplaces) and to rank working practices with respect to their contribution to risk within a workplace.08 1. C and D) all have a significant individual impact on risk by removing the potential for release or exposure of flammable vapour.00E-04 Figure 6.96 1. it could then be used to aid the risk analyst in determining whether due diligence is being given to fire hazards in current guidance.07 0.33 3.2 also shows that measures which make the process inherently safer (A. 3 and 5.00E-01 Good management control 1. sources M Control deliberate ignition N Proximity of staff Table 6.00E+04 1.34 Attribute measured A Material classification B Release quantity C Frequency of use D Containment E Spill and vapour control F Housekeeping G Safety management H Staff awareness I Maintenance and inspection J Control fixed ignition sources K Control static ignition L Control misc.33 0.98 1.00E-02 Low inherent risk 1.63 1.07 5.59 0.17 0.00E+02 High inherent risk Poor management control Raio of risk to average risk 1.04 0. the risk model appears to be consistent with the incident data presented in Sections 2.00E+00 Good fixed measures 1.09 1.78 1. both with respect to the content of guidance and the workplaces to which the guidance is directed.
foundries etc. L and M) also reduces the risk by a factor of around 20. This section uses the example of a garage handling petrol to illustrate the use of the model in identifying high risk practices.5. but only if all types of ignition source are removed from the workplace. B and C is not considered practical in a garage environment as petrol will always be present and its quantity and frequency of handling cannot be reduced. hence the importance of safety management in a workplace. This is consistent with the review of incident data as summarised in Section 3.2 of Section 6. attribute D.39 0. G. Failure or lack of implementation of permit-to-work systems and use of protective equipment were both found to be significant risk contributors (see Section 3. The model suggests that such control is important. it is possible to improve practices relating to the handling and containment of petrol. without prioritising those which are most effective in reducing risk to workers. G (safety management) and H (staff awareness).30 0. Control of ignition (attributes E.3 for a generic workplace containing flammable materials.4). The third column of the table shows the potential for improving the ratings for each attribute (to a level considered practical for a garage).e.70 0. and in particular. in general. where the presence of HFL/FLs was identified as being a key risk contributor in terms of material stored and handled. Risk was found to be highly dependent on containment of that material. D (the containment of that material). K.20 . as further discussed in Section 6. G. The model can be used to produce a ‘league table’ of mitigation or risk reduction measures in terms of their potential to reduce fire risk (although it is noted that the model is highly dependent on the subjective judgement used in deriving the model scores. Section 3. I and M reduces the risk by a factor of over 20. improvement in management controls F. Note that modifying the inherent attributes A. These fall under safety management. the workplace attributes which have the greatest effect on risk are A (the material stored).25 0. These ratings have been based on the incident descriptions identified in Section 5. and hence in assessing and directing guidance relating to this type of workplace. Good training and staff awareness were found to be important in reducing risk across all workplaces. However. chemical sites.3 summarises the ratings (i. although the major contributor is vapour control (E).3. Appendix F provides a step-by-step guide to data input to the model for this example. and illustrates how the model calculates risk based on this input. with a resultant reduction in risk by a factor of 3. generally a choice of either ‘good’.5 also identifies control of ignition sources to being significant with respect to fire risk.5). H. J.2 suggests that. as does the implementation of other preventative measures. The fourth column gives the risk reduction associated with each attribute if that attribute is changed from the original to the improved rating. The second column of Table 6.measures (or combinations of mitigation measures) which most reduce risk can then be given the correct emphasis. noting that much current guidance is prescriptive and lists the safety measures to be adopted. In fact.1.). G. The model suggests that the risk within garages is best reduced by improving safety management measures and increasing staff awareness. Table 6. Such a league table has effectively been produced in Table 6. but could also be done for types of workplace (e. Rating Attribute measured A Material classification B Release quantity C Frequency of use D Containment E Spill and vapour control F Housekeeping G Safety management H Staff awareness Original HFL Average Regular Poor Poor Poor Average Poor 33 Improved No change No change No change Average Good Good Good Good Ratio of improved to original risk 1 1 1 0. ‘average’ or ‘poor’) which might be chosen for a typical garage. C (the frequency of use of that material). the use of correctly lidded containers when the flammable liquid was being handled.g.
In four incidents involving draining tanks. K. which considers the workplace attributes (or combination of attributes). filling garage with vapour.39) Lessons learned from incident data Guidance provided in INDG 331 E.86 0. It was suggested that the main cause of casualties was the failure to follow the available guidance. K. G. Staff awareness (0. Do soak up spills immediately. Do use a fuel retriever. E. with a 34 .05) Do drain fuel outdoors.3 Risk reduction for garages handling petrol The HSE guidance of most relevance to garages handling petrol is INDG 331.97 1 0. H. Do use metal containers with secure caps. This is done in Table 6. H. operator had not used proper receptacle. One incident where oily rag not removed before hot work commenced.27x10-2 Ratio of improved to original risk 0. Don’t drain fuel over or close to a pit. which have a significant impact on fire risk. and hence a failure to educate the workforce in the potentially fatal consequences of misuse of petrol.75x100 7. Spill and vapour control (0. One incident involved a dropped tank in which safe working procedures were not adopted. Careless handling of petrol can cause fires and explosions.75x100 7.80 0.28x10-1 1. ignition sources not kept clear (one possible case of smoking) and/or ventilation was inadequate (one incident occurred in pit). No explicit safety management guidance except the following: Don’t allow work which can produce a source of ignition. and safety management. One incident of draining petrol tank in a pit (see below).04 0.Rating Attribute measured I Maintenance and inspection J Control fixed ignition sources K Control static ignition L Control misc. G. Do use earthing straps.98 0. Do ensure containers cannot be knocked over. L and M. Two incidents were due to careless practice of removal of fuel lines while engine running. L and M) Safety management (F. This view is confirmed by the model results. In one incident. I and M) Total risk levels (all attributes) Original Poor Poor Poor Poor Poor Average 7. It is of interest to compare the content of INDG 331 with the results of the model given in Table 6. sources M Control deliberate ignition N Proximity of staff Control ignition (E. Ignition Control (0. Many incidents involved welding as ignition source. J.20) and G. as INDG 331 was considered to be concise and explicit in this respect. G. Don’t drain fuel into open-topped containers. Do drain outdoors or in a wellventilated area. Do disconnect battery before draining. Attribute (ratio of improved to original risk) H. Safety management (0. Do remove petrol by filler tube. ‘The Safe Use of Petrol in Garages’.3.79x10-1 3.1 suggested that there were no specific problems with the identification of hazards in the guidance. Don’t drain fuel into plastic containers.4 Lessons learnt for garages handling petrol The incident review in Section 5.05 0.25) D.75x100 Improved Average Average Average Average Good No change 3. which show that the attributes of staff awareness. Don’t use any electrical equipment while draining in progress. have a significant effect on the modelled risk. J. Containment (0.4 below. Table 6. INDG 331 is a document primarily aimed at employees.3 and the incident data summarised. G. One incident where operative had used bucket rather than proper receptacle to drain petrol tank.97 0. Don’t allow smoking in the area.30) Evident that most incidents were due to failure to follow guidance rather than deficiency in guidance. Plus see above regarding not allowing smoking and ignition sources. One was where attempt was made to drain tank by running engine.002 Table 6.
4 is limited.4. The importance of these measures is evident from both the incident review and their coverage in the INDG 331 guidance. For example. E.4 shows that the model correctly identifies the attributes of spill and vapour control. It contains some explanation on how the fire hazards occur.5 Summary and model limitations Although the evaluation of the model in Sections 6. although the effort required for this could be limited by concentrating on flammable liquid hazards. Thus it does not consider general fire precautions nor process fire precautions such as separation or segregation of flammable materials or directed forms of water spray or deluge. This observation is consistent with the incident review. the following points would need to be considered during any trials of the model.3 and 6. The list of workplace attributes is based on the key risk contributors identified within the limited data set. Similarly control of ignition sources is key to risk reduction.poster listing what not to do and what to do when handling petrol. The potential applications of the model have been outlined in Section 6. as being key risk reduction measures. D. Where scores could not be derived quantitatively. For example. The latter may have a possible benefit in reducing the immediate effects of an event but no incident data was found to support this and this is not included in the model. although the model results show that all ignition sources must be controlled if petrol spills are not to be ignited. Table 6. It is also shown to be potentially useful in identifying gaps in guidance. and containment. More detailed consideration could then be given to the ranking of workplace attributes and. The sensitivity to this model simplification requires investigation. or how safety should be managed in a garage (for example with respect to implementation of procedures for draining fuel lines or tanks or undertaking hot work). the model results could be used to argue that there should be more explicit guidance to employers (which would complement INDG 331) on training of staff in fire hazards and managing safety through implementation of procedures for hazardous operations. for garages handling petrol. the worked example for garages handling petrol shows that the model is broadly consistent with incident data and also with current guidance. However. scores could be derived quantitatively. In summary. However. The present implementation of the model does not fully consider all the relationships between each workplace attribute or precaution. where possible. and some discussion on the severity of the hazards. Certain mitigation measures are only of benefit for certain handling operations. if the full benefit of the model is to be obtained: § The scores attached to each attribute within the model are based on a limited data set and rely heavily on the judgement of the authors of this study. there is no explicit guidance available for garages on how staff should be trained in the dangers associated with handling of petrol. § § § 35 . the model framework is considered effectively to address the key contributors to risk within a workplace containing HFL/FLs. there would be value in the wider use of experts to derive scores. lidded containers are only of benefit where handling of HFL/FLs in containers is predominant. The attributes would need to be reviewed in the light of more comprehensive data and would need to be checked for consistency with criteria which are currently used to assess workplace risk. and the probabilities attached to measures may be conditional upon other workplace attributes. 6. If the model is to be developed further then more than one year of HSE data would need be reviewed. The present implementation of the model considers only the immediate effects of an event in terms of fatalities or injuries and does not consider escalation of an event.
the attributes used in the model are generic to all workplaces and. and is designed to be suitable for use by risk analysts. Section 6. However. For example. the user must then decide how that attribute can be improved in the particular workplace. as recommended by INDG 331. the calculation of risk (and the potential for risk reduction attached to each attribute) is time-consuming. etc.4 showed how the model could be used to identify and rank workplace attributes with respect to their impact on fire risk. § § 36 . Although the model structure is simple. allowing the user to identify efficiently the key risk reduction measures for a workplace or type of workplace.4). having identified a workplace attribute which requires improvement. the model descriptions require testing against a range of workplaces to verify that the descriptions are both suitable and not easily misunderstood. the model may identify ‘Spill and vapour control’ (Attribute E) to be an important risk reduction measure for garages handling petrol (see Section 6. Thus the model would best be implemented as a computer model or spreadsheet.§ The input to the model comprises an assessment of the workplace against a set of descriptions. However. but it cannot be used to show that this attribute can be improved by removing petrol via the filler tube.
7. or otherwise. but once it had occurred. implementation of work procedures. A shortfall in either does not generally cause ignition.1 CONCLUSIONS Key conclusions of review of incident data and current guidance The HSE incident data was found to provide a sufficient level of detail to allow identification of key risk contributors within workplaces. as well as appropriate physical measures. However. General § The review of fire incident data suggests that good safety management. There was no evidence in the incident data to confirm. in terms of immediate injury or fatality. Fire Protection § Sprinkler systems are generally effective at controlling fire and reducing the risk to the building occupants. and make a significant contribution to the level of safety. Successful elimination of static is difficult to achieve and requires good staff training and careful control. were shown not to make a significant contribution to reducing immediate fatalities or injuries. Building protection measures. and training of staff. including the use of risk assessment. and not their successes. because only their failures. is key in reducing flammable hazards within the workplace. the presence of poor housekeeping and maintenance tended to exacerbate the severity of the incident. The review of the fire statistics and HSE data showed that the presence of flammable solids does not represent a significant fire risk. § Fire Prevention From the review of incident data it was not possible to determine the effectiveness of fire prevention measures. by controlling fire growth and allowing increased time for evacuation. are recorded. Significance of flammable substance § § § § The review of fire incident data and statistics identified that the use of flammable liquids represented a significantly greater risk of fire compared with the use of gases and solids. they are less likely to be as effective in preventing injuries or fatalities in incidents involving rapidly growing fires or explosions. that directed forms of water spray or deluge systems were effective in preventing injuries or fatalities. Permit-to-work systems and their enforcement are key measures in preventing injury or fatality of those undertaking maintenance or repairs. The incidents involving flammable liquids also tended to lead to more serious injuries due to the speed of fire development and close proximity of the operatives. § § 37 . It was however possible to draw three general conclusions: § Good housekeeping and maintenance are important preventative measures. The HSE data showed that the use of gases is also a significant risk factor with 16% of the incidents reviewed involving them. 7. The key findings of the incident review are listed below. such as compartment walls and bunds.
rather than any deficiency therein. the model has the following limitations: § The scores attached to each attribute within the model are based on a limited set of HSE data and rely heavily on the judgement of the authors of this study. a simple model has been developed which can be used to identify key risk reduction measures for workplaces containing highly flammable or flammable liquids. although it is noted that there is much uncertainty in the derivation of the scoring system used in the model. 7. § § 38 . The results of its application were found to be consistent with the review of incident data conducted in this report. The study presented no evidence that the guidance for fire safety in solid materials requires improving. The incident data could not be used to show that the level of training. depends on the company size. § § Effectiveness of guidance by type of premises § The guidance in the leaflet ‘safe use of petrol in garages’ is concise. INDG 273. § Influence of company size § In the review of 41 incidents selected from HSE and Fire Brigade data. and deals with the relevant issues. a key fire prevention measure is the use of properly lidded containers when transporting smaller quantities throughout the work place. there would be value in the wider use of experts to derive scores. As discussed more fully in Section 6. the most significant cause of incidents was identified as failure to follow the available guidance. The fire safety section in the leaflet ‘Working safely with solvents’. the review of the incident data showed that this industry had a good awareness of the fire issues and that there was no evidence that the guidance for this sector needed to be improved. The list of workplace attributes would need to be reviewed in the light of more comprehensive data and would need to be checked for consistency with criteria currently used to assess workplace risk. Effectiveness of guidance by material type § When assessing the effectiveness of guidance against incidents involving highly flammable liquids. rather than any deficiency in the guidance itself.3. Although there was a relatively large number of incidents in the chemical industries. The present implementation of the model considers only the immediate effects of an event in terms of fatalities or injuries and does not consider escalation of an event. company size was not shown to be a significant risk factor. flammable liquids.§ For flammable liquids. Where scores could not be derived quantitatively. or implementation of safe working practices. gases and solids. The ongoing issue of the frequent number of fires of this type is due to the guidance not being followed. It is considered that the HSE incident reports are of sufficient detail to allow the quantitative evaluation of scores if the dataset were to be widened beyond one year. does not adequately address the fire safety issues associated with all solvents.2 Development of risk assessment method Based on a qualitative assessment of the HSE data.
it could be used to aid risk analysts in determining whether due diligence is being given to fire hazards in current guidance. and consideration given to whether the derivation of model scores could be made more quantitative. Potentially. The sensitivity to this model simplification requires investigation. and whether further attributes relating to event escalation are required. Any trials of the model should consider the above model limitations. HSE incident data spanning a number of years for HFL/FLs in this workplace type could then be reviewed in detail. The attributes used in the model are generic to all workplaces and. the calculation of risk is time-consuming. 39 . Consideration could also be given to whether the generic descriptions used for the model attributes are applicable to this workplace. having identified a workplace attribute which requires improvement.§ The present implementation of the model does not fully consider all the relationships between each workplace attribute or precaution. allowing the user to identify efficiently the key risk reduction measures for a workplace or type of workplace. Although the model structure is simple. the user must then decide how that attribute can be improved in the particular workplace. It is recommended that this is best done by conducting a trial for a particular type of workplace. and requires testing against a range of workplaces to verify that the descriptions are suitable. Thus the model would best be implemented as a computer model or spreadsheet. The input to the model comprises an assessment of the workplace against a set of descriptions. The model could then be tested against selected workplaces. Much current guidance is prescriptive and so the model could be used to prioritise those precautions which are most effective in reducing risk to workers. both with respect to the content of guidance and the workplaces to which the guidance is directed. § § § The model can be used to rank workplaces with respect to fire risk and to rank working practices with respect to their contribution to risk within a workplace.
Fowler A. England. 5. H..J. explosions and related incidents at work in Great Britain in 1994/95 and 1995/96.W. Borehamwood.’ Journal of Loss Prevention in the Process Industries. ‘Fire Statistics United Kingdom 1997. 11. ‘Ignition Probability of Flammable Gases’. CRR 146/1997. February 1982. S. Health & Safety Executive. AIChE.K..REFERENCES 1. 2000. H. and Thorne. 1997. 10. Australian Fire Protection Association. 1988. 7th Edition. P. British Standard Institution. Statistical Press Release. RIDDOR. Levels of Reporting of Workplace Injuries.H. Ames. P. 12. Lees. DTI. & Rew. ISBN 0 7176 1431 X.S. Marryatt. ‘The FPA large loss analysis’.A. 7. 11 (5). Small and medium enterprises (SME) statistics for the UK. 8. HSE Books. 1995. 40 .. ‘Fire: A century of automatic sprinkler protection in Australia and New Zealand. December 1999.P. 2. Reporting of Injuries.F. 1994. Home Office. Butterworth Heinemann. New York. Diseases. 1886-1986’. 4. 1998. & Hazeldean J. Fire Research Station. Fire Prevention 327. and Dangerous Occurrences Regulations.. 3. 6. 2nd Edition. 9. F. 1999. DD240: Part 1: 1997: Fire Safety Engineering in Buildings. ‘Fires. Fire Protection Association.. Dow’s Fire & Explosion Index Hazard Classification Guide. Spencer.’ November 1998. 1995. ‘Loss prevention in the Process Industries’. ‘Study of the Effect of Sprinkler Systems on Fires Involving Furniture in a Retail Environment’. 1998.
APPENDIX A Home Office Fire Statistics 1997 Material first ignited Total* Main gases LPG Acetylene gas Other Petroleum Paraffin Diesel oil. fuel oil Paint.Deaths and casualties for fires in other buildings by material or first item ignited [2] 41 .383 Fatalities 32 0 0 0 1 3 0 0 0 0 2 1 10 Non-fatal injuries 2.111 70 21 5 7 105 6 7 17 16 29 72 162 * for all fires in buildings other than dwellings (including paper. while rest of table is for incidents involving liquids and gases only Table A. food and other solid combustibles). cardboard.426 133 125 72 29 954 121 146 270 442 135 525 4. varnish Other oils Spirits Other Unspecified No of fires 44.1 .
Fatalities caused by improper use of gas equipment. Major burns caused by static igniting solvents.APPENDIX B Break Down of Fire Incidents With Respect to Company Size Reference Small HSE Incidents 4 5 9 13 14 17 19 22 23 25 32 36 38 42 44 45 46 47 49 57 58 60 64 67 74 85 69 87 89 93 66 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Company Size Medium Large Comments 78 62 Fire Brigade incidents FB(III) 1 FB(VI) 1 FB(V) FB(VII) FB(VIII) FB(IV) FB(I) FB(II) 1 1 1 Minor injuries. Acetylene gas ignited because of defective valve. Inadequate risk assessment. Fat fire in extract duct led to major roof fire. Unexplained accident as proper precautions were taken. Inadequate risk assessment. Failure in maintenance procedures. Oxygen cylinder fire as full cylinder was being incorrectly de– rigged. Serious incident. No injuries. Minor incident. Use of HFL with inadequate precautions. Fault rectified by mixing in appropriately zoned area. Inadequate ductwork design and lack of cleaning. Serious fire. Unsafe working practices with HFL used for cleaning. Fire extinguished by sprinklers. Malicious fire. Fire caused by maintenance accident on spray booth. No injuries. Fire caused by design fault not failure to follow guidance Minor incident. Two workers killed engulfed in flammable liquids. Serious fire. Minor incident unidentified cause. Major burns. but no serious injuries. Fire controlled by suppression. Major burns to one employee and minor to other. Ruptured pipe in LPG heater caused minor burns. Changes to procedures to remove risk of static. Serious fire. 1 1 1 42 . Minor incident. Precaution of fire crew and occupants taken to hospital. Possible cause was poor maintenance. Minor fire. Plant destroyed due to fire during maintenance. Minor fire. Aerosol fire led to major building loss. Small fire. Minor fire highlighted lack of training and poor maintenance Fire extinguished by suppression. Minor incident procedures modified. Fire brigade summoned by detection and alarm. Poor control of HFLs. Minor fire during maintenance. Major burns. 1 fatal and 1 major injuries. All precautions taken. Major burns. but no injuries. No injuries but serious fire. Significant fire concerns about smoke inhalation. Caused by unforeseen circumstances. Minor injuries. inadequate control of HFLs. Lighter fuel ignited when electric heater placed to close. Fire caused by solvent splashing into unearthed bucket. but fire spread through manufacturing area.
a place of special fire risk cannot be an inner room. 2000. provide a protected and ventilated lobby between the room and a protected staircase. spread and extinction. provide fire separation. site layout building.1 C. and fire prevention and fire defence.2 b) ‘Service installation rooms in which flammable liquids or gases are used or stored should have imperforate sills to doorways and any necessary drainage should be provided with interceptors’. primarily for normal operating processes. There are standards of electrical equipment that are specified as appropriate for use in each zone. having a minimum standard of fire resistance of 60 minutes’. operation and maintenance.1. process design. protect lifts by a lobby when they serve a floor that contains a place of special fire risk. Table 11 of this code of practice recommends that for: ‘Repair and maintenance workshops where flammable or highly flammable liquids are used or stored’ this area should be separated from other parts of the building by ‘robust solid non-combustible construction. BS 5908: 1990: Code of practice for fire precautions in the chemical and allied industries. offices. storage space for fuel or other highly flammable substances and rooms housing a fixed internal combustion engine. 43 . storage and other buildings. Covers flammable liquids under places of special fire risk.1. the introduction of temporary ignition sources. this code of practice is only likely to be applied to hazards in the chemical and allied industries.4 BS EN60079: 1996: Electrical apparatus for explosive gas atmospheres. are covered by the use of permit-to-work systems. boiler rooms. The section on fire prevention and defence covers control of ignition sources.e. However. Approved Document B: Fire Safety. structure.1 Building Codes BS 5588: Part 11: 1994: Code of practice for shops. which defines zones where the risk of a flammable leak is at the same level. This recommendation is augmented by 16. the standard also recommends procedures for minimising the risk of leaks and ignition. but the standard provides recommendations on which sources may be tolerated in different areas (although the aim is usually to have no ignition sources at all in hazardous areas). Faults and maintenance operations. The many different forms of non-electrical ignition source do not have such clear classifications. as defined in the scope. C. which are defined as oil-filled transformer and switch gear rooms.1. BS 5908 provides broad guidance on dealing with flammable substances. C.3 limit the travel distances to 9 m when escape is in a single direction and 18 m when available in both.2 The Building Regulations. i.1. detection and suppression.APPENDIX C Summary of Guidance C. BS EN60079 is the main European standard for suitable equipment selection for explosive gas atmospheres. Its recommendations deal with the principles of fire initiation. As well as specifying controls on the type of ignition sources. The main feature of the code is area classification (Part 10). The precautions it recommends for places of special fire risk are: · · · · · C. industrial. and storage.
This guidance is aimed at those directly responsible for the safe storage and handling of flammable liquids in containers in all general work activities. they decompose on heating. HS(G)51 This provides guidance on the control measures you could adopt for the safe storage of containers containing flammable liquids. HS(G)103 This provides guidance and advice on ways of complying with legal requirements. Information and training. For premises manufacturing more than 50 tonnes of cellular plastics. Human factors. Prevention. the storage of small quantities of flammable liquids within a workroom. large bulk storage should be in a separate building. limiting the amount of materials stored.2. C.2 C. and 1 hour in multi-storey buildings.3 The storage of flammable liquids in containers. rooms or cabinets. C. where cut. Precautionary measures. Fires. Hazards. These include the storage and handling of flammable liquid in containers. C. although some general advice is given on health risks where this may be helpful. It applies to new or existing sites. Protection. Safety precautions. Risk assessment. HS(G)178 This is aimed at managers and supervisors who control spraying operations.2. HS(G)92 The main fire precaution emphasised is fire separation to at least 30 minutes in general. managers.C. etc. the dust regularly needs extraction with explosion relief. and large drum storage and distribution areas at manufacturers' or suppliers' premises. Characteristics of dust explosions. It provides guidance on the hazards of spraying with flammable liquids and preventive and protective measures to reduce the risk of fire and explosion. Some may react with air or moisture and. Spray methods. 44 .5 Energetic and spontaneously combustible substances identification and safe handling. Handling and storage. or in specifically designed buildings. foremen and safety representatives in the many industries were combustible dusts may be present. Emphasis is also put on good house keeping. PU dust is flammable and. apply.2.2. Its contents include: Legal requirements. Effects of a dust explosion.e. Inspection and maintenance. The contents include: Hazards. providing separate bins for flammable lubricants. In this case HSE will issue the certificate and enforce its provisions. i. Fire precautions and emergency procedures. Fire precautions and emergency procedures. Its contents include: Legal framework. although they may be stable at normal room temperatures. It describes in non technical terms the hazard from dust explosions and common means to control risk. Storage facilities. The definition given in the guide is that energetic materials are those capable of undergoing rapid exothermic decomposition or polymerisation leading to either a fire or an explosion by deflagration or a detonation. It is aimed at employers. Legal requirements.1 HSE Documents Safe use and storage of cellular plastics. It sets out the steps which need to be taken to control the risks of fire and explosion. Control measures. possibly after a prolonged time.4 Safe handling of combustible dusts. the Fire Certificate (special premises) Regulations 1976.2 The spraying of flammable liquids. The guidance applies to all storage locations whether in the open air.2. Interconnected plant. C. HS(G)131 This provides guidance on what comprises energetic substances and the conditions for which they may be unstable. Spray areas. Where possible.
The guide also contains recommendations concerning hot work permits. oxygen can be dangerous especially in confined spaces. to use guards to prevent hot particles passing through openings in floors and walls. Additional precautions may be necessary when there is an enhanced risk of fire from combustible materials that cannot be moved. which can take a considerable time to cool down. to ensure that any explosion is vented. or hot workplaces. flame cutting and allied processes. The emphasis in the guidance is on good housekeeping and.Guidance is provided on identifying energetic substances. but also from slag. minimising risks by alternative cutting methods. buckets of dry sand or formulated powders where there is a risk of metal fires. At concentrations above 25%. type. HS(G)158 This guide provides specific guidance on the construction. for which recommendations are given in two sections. to remove combustible materials from the vicinity. The main precautions it recommends are the good practices of using proper equipment. including fire watchers and buckets of water to damp down and cool surrounding areas. etc. It also gives guidance on the legal requirements relating to their installation and use. combustion is more hazardous. Recommendations are provided on extinguishers. on ‘Appropriate fire precautions’. Staff should be trained and adherence to correct operating procedures should be ensured. C. The second section. burn at higher temperatures and can be difficult to extinguish. or at pressures above atmospheric. refers to the need to assess hazards before work.2. describes the hazards associated with acetylene. It discusses how fires may arise not only from direct flame contact.2. other fuel gases and oxygen. Drying at elevated temperatures needs to be controlled carefully to ensure that it does not lead to a runaway reaction.7 The safe use of compressed gases in welding.8 Flame Arresters. controlling the risk and general good working practices of inspecting goods for damage and ensuring that they are not stored where they can be heated (in sunlight). on ‘Fire Explosion and other Hazards’. 45 . removal of ignition sources and good ventilation. in particular. C. siting and maintenance of flame arresters. Energetic substances should be stored in fibreboard packaging. HS(G)140 The scope of this guide defines ‘flammable liquid’ as one with a flashpoint of 55oC or below. Processing equipment should minimise friction and heat generation to avoid initiation of decomposition. Appropriate fire precautions should be taken. or fibreboard crates. Materials ignite more easily. The guide cautions that CO2 and Halon can react with chemicals to create fire. labelling.6 The safe use and handling of Flammable Liquids. HS(G)139 This document deals with general safety precautions as well as fire. It advises that. regular maintenance and ensuring safe cylinder handling. Water is recommended as the preferred extinguishing medium as it removes heat. storage and bulk supply facilities. Its main recommendations are: § § § § to move work pieces to safe locations for hot work processes to be carried out. to protect any combustible materials. C. in oxygen concentrations above 21%. concerns the transfer and decanting of liquids with special containers.2. The first section. but it is necessary to ensure that extinguishers are compatible with the stored materials.
Expanded polystyrene. The precautions are based on general fire safety practices of good means of escape. Inspection and maintenance.9 The storage of flammable liquids in tanks. Flexible polyether PU foam. powders or dust or from certain reactive solid and liquid chemicals. and identifies fire hazards resulting from the escape of flammable gases or fluids. gases. a high risk material may be less dangerous in a large volume than a medium risk material in a small building. A 5 kg sample is burnt and the temperature rise and smoke production are both measured. INDG 308 The introduction identifies that accidents involving gas cylinders can cause serious death or injury. rubber. Note that. Location and layout of tanks.1 HSE Leaflets The safe use of gas cylinders. HS(G)64. sodium chlorate and organic peroxides. Legal requirements. Training. alarm. ISBN 0-7176-1786-6. It also gives the main causes of accidents as inadequate training.5 m wide. C. HS(G)176 This provides guidance on the design. A high hazard material is defined as having a rate of temperature rise greater than 700oC per minute. construction. The guide gives examples of solid materials.C. backed up with good house keeping i. fire separation.10 Assessment of fire hazards from solid materials and the precautions required for their safe storage and use. This uses a 1 m3 room connected to a corridor approximately 6 m long by 1 m high by 0. including rigid and cellular plastics. Risk assessment.e.e. Emergency procedures.3 C. operation and maintenance of installations used for storage of flammable liquids in fixed tanks operating at or near atmospheric pressure. paper and textiles. Loading and unloading facilities. poor handling and poor storage. i. Design and construction. Rigid PU Foam (low density). This guide introduces the HSE test procedures for identifying high fire hazard materials. faulty equipment. Textile Industry Advisory Committee.3. Fire precautions.2. minimising ignition sources and waste. Higher-flashpoint liquids. The advice given will be useful for those who manage small businesses. Polypropylene sliver. C. HS(G)64 is no longer on sale but its key contents are broadly covered by: Fire precautions in the clothing and textiles industry. 2000. such as LPG. Acrylic mixture. or for which the total volume of smoke produced is more than 400 m3. poor maintenance. Acrylic over locks. as discussed in Section 4. poor installation.3. Materials that that have been identified as High category: · · · · · · · Acrylic fibre. such as ammonium nitrate. The guide also makes the valid point that risk is also related to building layout. Security. 46 . manual extinguishers.2. Its contents include: Fire and explosion hazards. A note to the introduction excludes the dangers posed from storage of flammable liquids.
INDG 331 This is a single page two-sided information sheet providing guidance on avoiding fire hazards associated with draining petrol tanks. The leaflet describes the health hazards. extremely flammable. No specific fire safety advice is provided.3. INDG 181 This guide to CHIP (Chemical Hazard Information and Packaging) does not contain specific fire advice but makes it clear that chemical suppliers along the complete supply chain must ensure that the hazards associated with the substance are correctly identified. sparks and hot splatter. oxidising. rather than the fire hazard. clamping work pieces not hold by hand). C.The guide gives guidance on training. can be undertaken by a competent person. Keep fire extinguishers nearby. Within these classifications there is the category of physico-chemical. and runs to 14 pages. It defines a solvent as a chemical substance used to dissolve or dilute other substances and gives a range of industries where solvents are commonly used and products that contain them. filling. Key precautions are never to allow oil or gas to come into contact with valves or cylinder fittings. lifting. and storage. The recommended precautions are: · · · · · · · · Move the work piece to a safe location. handling and use. C.4 Safety in gas welding. It also makes it clear that cosmetic work. initial integrity and continuing integrity. cutting and similar processes. the importance of training and the dangers of lighted blowpipes (i.2 Working safely with solvents. it discusses the toxic gases that can be produced from chlorinated solvents. INDG 273 This is a two page leaflet which highlights that solvents can seriously damage your health. INDG 297 This guide is more comprehensive than other HSE leaflets. Ventilate spaces where vapour could accumulate. making the point that clothing contaminated with oxygen can burn fiercely even if fire retardant.e. Protect any combustible materials that cannot be moved using fire resistant blankets. It makes it clear that it is an offence to modify or make major repairs to the body of seamless gas cylinders or cylinders that have contained acetylene. It recommends the permit to work system. The leaflet also provides a section on misuse of oxygen. such as vehicle pits or trenches.3. and never to use oxygen with equipment for which it is not suitable.3 The complete idiot’s guide to CHIP. C. highly flammable. and hence the precautions that should be taken when working with solvents. or flammable. Use guards to prevent hot particles passing through openings in floors and walls Maintain a continuous fire watch during the period of the work and for least an hour afterwards. which comprises: explosive. Remove any combustible materials from within 10 m of the work. but in the terms of the hazards presented. not related to the integrity of the cylinder. The leaflet contains a specific section on fire and the dangers of the flame.3. C. It gives advice on not using solvents in areas where flames are present.5 Safe use of petrol in garages.3. Advice is given on the need for good ventilation and 47 . Check for hidden combustibles behind cavities. transport. etc.
C. TIS 2 This leaflet provides abbreviated recommendations on the storage of flammable liquids likely to be used in the textile industry. It details how various petroleum products fall into these categories and provides advice on safety measures to be adopted for various classifications. It comprises 9 comprehensive sections covering plant location and safety distances. IAC/L85 This leaflet contains abbreviated advice on fire risks. gases. The punch line is keep a strong grip on workplace safety. installation and maintenance practices to avoid the risk of fire or explosion from the use of electricity. if practical by a physical barrier. Institute of Petroleum.2 Model code of safe practice for the petroleum industry Part 15. rail and marine loading and discharge. 6th Edition (7th Edition in preparation). including lightning. 1991. 1998. It also provides an alternative point source calculation method. It advises on control of ignition sources and correct transfer and storage of petrol.4. Separation of flammable substances from other processes. INDG 227.4 C. to disperse fumes.8 Solvent safety in printing. Area Classification Code for Petroleum Installations. oxygen and reactive chemicals. This provides a large number of examples of hazardous area classifications including onshore and offshore drilling operations. The introduction to this leaflet makes it clear that small quantities of flammable materials can be found in most workplaces.4. installation and commissioning.4.3 LPGas Association – Code of Practice 1. More specific guidance is also given on flammable liquids. dusts. 1st Edition. which will be withdrawn. static. installation and operation of vessels located above ground. It defines the six classifications of flammable liquids: Classes 0. fire precautions. This describes equipment selection. II(1). road. This Code of Practice replaces both the 1991 edition and HSE publication HS(G)34 "The Storage of LPG at fixed installations". design of the vessels and associated equipment.3. Exchange. Ignition. C. I. It introduces the concept of VICES · · · · · Ventilation. Bulk LPG Storage at fixed installations. 1990. III(1) III(2) and unclassified.correct equipment such as a proper fuel retriever. bulk storage. flammable substance for less flammable or eliminate. C.7 Non-dyestuff chemicals: Safe handling in textile finishing. operations and records. Institute of Petroleum.6 Safe working with flammable substances. Part 1: Design. C. removal of all obvious ignition sources. taken from the larger booklet ‘Fire safety in the printing industry’. Containment.3. C.3. C. Electrical safety Code. and radio frequency emissions. II(2). electrical requirements. 48 . suitable lidded containers and spillage trays.1 Other Guides Model code of safe practice for the petroleum industry Part 1.
The precautions included in the model are covered by attributes D.5 0.e.7 0. f. frequency of use. Section 6. or handled.5 Frequent 30 Average 0. probability of ignition. the frequency of release is calculated from the attribute scores using event tree analysis.1 that poor implementation of a precaution gives a score of 1 and thus.1 0. the lower the ‘good’ and ‘average’ scores 49 .2 0.APPENDIX D Development of Risk Assessment Model D. R. The attributes were ranked in terms of their effectiveness and the more effective a measure was considered to be. This is reduced to 30 for workplaces where HFL/FLs are handled frequently and to 10 for workplaces where HFL/FLs are used only occasionally. whether used continuously within a process or occasionally for cleaning/maintenance. a I where the values for each score are defined in Table D. Attribute C D F G H I Frequency of use Containment Housekeeping Safety management Staff awareness Maintenance and inspection aC aD aF aG aH aI Continuous 100 Good 0. as demonstrated by the available incident data and based on the judgement of the authors. is calculated as the product of release frequency. that all precautions need to fail for the incident to occur).2. H and I. the frequency.3 0.2.2 0. if all measures are implemented poorly.2) Occasional 10 Poor 1 1 1 1 1 Table D. This is characterised using attribute C. It is assumed that all precautions act independently and that each precaution is sufficient on its own to prevent a release (i. This base frequency is then factored down depending on the implementation of precautions designed to reduce the likelihood of spillage or exposure of HFL/FLs.1. frelease. Section 6. a D .1. Thus. continuously. noting that this is a notional value and is not based on incident data. G.9 0. p ignition .8 (D. as follows: f release = a C . However. a G .1 Scores for release frequency attributes It can be seen from Table D. These values are based on a qualitative review of the incident data and are scaled down from the maximum value of frequency of 100.1) The frequency that flammable liquid is spilled or exposed will depend on its use within the workplace.5 0. pinjury: R = f release . a H . F. is equal to the frequency of use score. A frequency of 100 is assigned to workplaces where HFL/FLs are used.2 Release frequency (D. in Table 6.e.1 General The risk. i. pignition. aC. and probability of injury or fatality. defined in Table 6. there is insufficient data to justify doing otherwise for the simple model developed here. p injury D. a F . The derivation of the good and average scores is based on the potential effectiveness of each precaution.1. This may be an over simplification for some precautions as there will be interdependencies.
50 . with a ‘good’ score of 0. Section 6.2.1 to 0. B and E are set to ‘poor’. This is covered by attribute G (in Table 6. The scores are summarised in Table D.k (b J + b K + b L + b M ) b A b B b E (D. with bE=0.3) Immediate or event-initiated ignition occurs predominantly during maintenance activities. is calculated from the probability of immediate and delayed ignition. B and E in Table 6. The probability of delayed ignition is then calculated within the model as follows: p delayed = 1 . Section 6. D. using event tree analysis. using a similar ranking process to that described above for the frequency attributes. The scores are based on a qualitative assessment of the effect of each attribute.e.g.2. i. or delayed (until the flammable vapour builds up and reaches an ignition source).p delayed ) (D. The probability of ignition. Thus the key contributor to event-initiated ignition is lack of work procedures controlling maintenance activities.p immediate ) (1 . The volume is then scaled down from the maximum cloud size using the ‘good’ and ‘average’ scores. bG ranges from 0. Thus the maximum probability of delayed ignition is approximately twice that for immediate ignition. or else ignition may not occur at all. The volume of flammable vapour depends on the flashpoint of the flammable liquid with respect to ambient temperature (or the temperature at which the liquid is handled).2.3 Probability of ignition Once a release has occurred. pignition. and results from poor control of ignition sources (e. Thus containment (D) is considered to be the most effective measure in reducing release frequency with a ‘good’ score of 0.4) where m is the volume density of ignition sources and V is the volume of the flammable vapour. As shown in Table D.2). K.µV (D.e . The probability of ignition is based on work presented in [12] and can be modelled as follows: p delayed = 1 . and the probability of immediate ignition is equal to the ignition probability score for attribute G. bA=bB=bE=1.(1 . ignition may be immediate (typically due to an ignition source being related to the cause of the release).assigned. safety management.2. L and M in Table 6. Section 6.e . which is consistent with the HSE incident data.5) where k is a constant of proportionality. The density of ignition sources is modelled via the scores attached to attributes J. The probability of delayed ignition is a function of the volume of the flammable vapour produced by the release and the density of ignition sources in the area local to the release. Thus it is modelled via attributes A. pimmediate = bG.5. i.g. giving a maximum probability of delayed ignition of close to unity.7. The volume of flammable cloud is at its maximum when the attributes A. failure to evacuate storage vessels). The value of k is set to 2. hotwork) or poor control of flammable materials in the vicinity of the maintenance activity (e. as it is assumed that lack of work procedures may result in immediate ignition of up to 50% of flammable releases. where it can be seen. as follows: p ignition = 1 . and housekeeping is considered to be the least effective.1. the spill quantity and the measures in place to limit the spread of the release and to remove flammable vapour.1.1.1.2. for example.e. that ‘good’ spill and vapour control will result in a factor of five reduction in volume of flammable cloud. pimmediate and pdelayed.
3.The incident data suggests that fixed ignition sources (such as hot surfaces.1 Small 0. Attribute A B E G J K L M Material classification (flash point) Release quantity Spill and vapour control Safety management Control fixed ignition sources Control static ignition Control misc.4 Probability of injury or fatality The probability of injury or fatality.1 FL 0. Attribute A Material classification (flash point) cA cB cE cN HFL 1 Large B Release quantity 1 Good E N Spill and vapour control Proximity of staff 0.6) The scores for probability of injury are summarised in Table D. However.5 0.05 0.5 0. It is assumed that the maximum number of people injured in an incident is two. the size of the flammable cloud is modelled via attributes A.1 0.3 Scores for probability of injury attributes 51 . sources Control deliberate ignition bA bB bE bG bJ bK bL bM HFL 1 Large 1 Good 0. proximity of staff.7 0.5 Average 0. electrical and flame) provide the greatest contribution to ignition.2. other ignition source categories are considered to have densities of up to 30% of the fixed sources. The ‘good’ and ‘average’ scores are then scaled down from the ‘poor’ scores based on a qualitative assessment of the effect of each attribute.5 c A c Bc E (1 + c N ) (D. The probability of injury is calculated using event tree analysis.5 FL 0. as follows: p injury = 0. certain operations may require the use of two or more personnel. Again the scores are based on the judgement of the authors and are derived using a ranking process.5 Average 0. as most events occur when personnel are handling HFL/FLs or when personnel introduce ignition sources into areas containing flammable vapour. as summarised in Table D.1 0.2 Poor 1 0. Based on the HSE data.2 0. with bK.3 Average 0.2 0.1.2 Scores for ignition probability attributes D.3 0. bL and bM set to 0. given that ignition has occurred.3 for poor control. depends on the size of the flammable cloud ignited. Thus the number of people exposed to the incident is incremented via attribute N.5 Poor 1 1 Table D.1 0.7 Other 0.2.2 Small 0.1 0. It is assumed that there will always be one person in close proximity to the incident.2 Other 0. and so cN is given a maximum of 1. B and E in Table 6. Section 6. or the room in which the incident occurs may be small with other people in close proximity. and hence its severity. As for ignition.3 0.2 0. and the proximity of personnel to the incident.5 1 0.3 0.7 Average 0.3 Table D. with bJ being given a value of 1 for poor control.
HFL/FLs stored externally. Frequency of use / spill Frequent Regular Frequent or continuous use or exposure of HFL/FLs within room / process. HFL/FLs stored and handled external to building. refilling or cleaning with HFL/FLs. Some potential for leaks from storage within room. Liquids with flash point greater than 55oC including flammable liquid based products.g. Material flammability Highly Flammable Liquids Flammable liquids Other liquids B. typically petrol. Possible use of oxidising agents and oxygen cylinders. Containment Good Average Poor Storage in fixed tanks and piped to equipment if used in continuous process. HFL/FLs handled in poorly ventilated enclosure. at end of shift. E. solvents etc. Spill quantity Large Average Small Bulk use and / or storage of HFL/FLs. Occasional (weekly) maintenance / cleaning with HFL/FLs.APPENDIX E Descriptions of Attributes for Risk Assessment Model A. Transported in open containers. Average Poor 52 . Empty flammable liquid containers removed. Spills cleared immediately. Infrequent D. Poor and delayed clearing of waste. HFL/FLs (50 litres maximum) stored in fire-resisting cabinets when not in use. Tanks do not comply with suitable specifications and have vulnerable pipework and supports. C. Spill and vapour control Good Average Poor F. Process liquids exposed to operators. Liquids with flash point greater than 32oC but handled above flash point. External operation. e. Waste cleared immediately but to open containers. Frequent uncoupling of flammable liquid pipes. Liquids with flash point greater than 55oC but handled above flash point. Equipment regularly (daily) requires handling of. Rags and cloths used to clear spills are removed and placed in lidded metal bins. Housekeeping Good Flammable waste removed immediately to non-combustible containers. Area well-ventilated. Internal quantities limited to half-day or half-shift Liquids with flash point less than 32oC. HFL/FLs stored and handled in well-ventilated enclosure. HFL/FLs handled and transported in lidded containers. requirements. Liquids with flash point greater than 32oC and less than 55oC.
Use of forklift trucks and other vehicles prohibited. Average Poor K. No formal assessment undertaken but some of the above measures in place. Naked flame or radiant heaters. Some of the above features in place. Lightning protection provided (as appropriate). flame cutting or grinding) and other maintenance activities. Containers and equipment maintained on an ad-hoc basis. i. Overheating equipment in evidence. Informal control of contractor operations. hot surfaces. in event of breakdown or leakage. Only central heating or fixed convector heaters. Staff regularly reminded of hazards and safety procedures. No obvious sources of ignition in vicinity of HFL/FLs. Appropriate control on personnel clothing.G. splashing or spraying of liquids occurs frequently. Average Poor L. Permit to work system in place but not always effective. Staff awareness Good Average Poor All staff trained with respect to handling flammable materials. High staff turnover with little formal training. Tool material chosen to avoid impact sparks. Appropriate use of antistatic additives and static eliminators. Control other ignition sources Good ‘No smoking’ policy throughout workplace (and smoking areas provided). I. stirring.e. Electrical equipment / lighting is correctly fused and maintained. no potential for friction from faulty equipment. ‘No smoking’ policy within high hazard areas. Regular checks. Some but not all of the above measures in place. Handling. Safety management Good Hazards formally assessed and specific measures in place and enforced. Average Poor H. valves and flanges etc) and equipment. by competent person. particularly flammable liquid containers (empty or full). Evidence of rating of electrical equipment but not based on formal hazardous area classification process. Experienced staff but no regular training. periodic servicing and maintenance of containers (fittings. Over-familiarity with process. Protective equipment available and use enforced. Written permit to work system adhered to for hot work (welding. Very little inspection and maintenance carried out. Precautions against static hazards not considered. pumping. Maintenance Good Average Poor Formal maintenance regime in place. Control static Good Formal assessment of static hazards undertaken. No or little control of the above ignition sources. Control fixed ignition sources Good No obvious sources of ignition (naked flames and pilot lights. inexperienced staff. frequent visitors and/or use of contractors. Antistatic and conductive floors and footwear used. J. Hazardous area classification undertaken and portable and fixed electrical equipment rated accordingly. Average Poor 53 . No permit to work system or control of contractor operations.) in area. All metal objects are earthed and kept earthed.
External operation or low occupancy large room. but high occupancy room. Appropriate security measures prevent entry of unauthorised personnel. Operation undertaken by one person. No security measures but well-trained and experienced workforce. Inexperienced and/or youthful workforce. operation requires two or more people Well-trained and experienced workforce. 54 . Control deliberate ignition Good Average Poor N.M. Staff likely to be close to incident. Proximity of staff Good Average Poor Staff access to hazardous operations and areas is restricted.
3.2. Little inspection or maintenance carried out. a G . For the worked example.APPENDIX F Worked Example for Garages Handling Petrol F. frelease.1 Rating of attributes F. a D .1) 55 . Based on the ratings chosen for these attributes. Table F. Section D. Little or no formal control of smoking and vehicles moved in and out of workshop. Petrol is handled in reasonable quantities (although not in bulk). Operations generally involve 1 person but others will be in garage.1 and are given in Table F. F.1 lists the chosen ratings and provides comments on the choice of rating. The notional frequency of the release.2 from the release frequency scores for attributes C. J K L M N Control fixed ignition sources Control static ignition Control misc. Some informal control of fire hazards but no PTW. Attribute measured A B C D E F G H I Material classification Release quantity Frequency of use Containment Spill and vapour control Housekeeping Safety management Staff awareness Maintenance and inspection Chosen rating Comments on choice of rating HFL Average Regular Poor Poor Poor Average Poor Poor Petrol is the dominant flammable hazard. Petrol often handled in poorly ventilated enclosures and sometimes in pit.0 x 0.0 x 1. the ratings of the attributes have been chosen for a typical garage based on the incident descriptions given in Section 5. Equipment repaired when found not to work. Waste allowed to build-up and only cleared at end of shift. Petrol often transported in open containers. G. sources Control deliberate ignition Proximity of staff Poor Poor Poor Poor Average Table F. a I = 30 x 1. is calculated from equation D.2 as follows: f release = a C . Petrol handled on a daily basis.0 = 15 (F.1 Rating of attributes The first step calculating the risk for a workplace is to rate each attribute as either ‘good’.1. the corresponding scores are taken from Table D. ‘average’ or ‘poor’. the frequency of release is calculated using equation D.2 Calculation of release frequency As described in Appendix D.0 x 1. Lighting not classified and occasional use radiant heaters and other electrical items.2. Youthful workforce and no security measures. Little formal training of staff and frequent visitors. H and I. D. a H . a F .5 x 1. Static hazards not considered.
3. G.0 0.p delayed ) = 1 .e .(1 .4) .3.3.2 Scores for release frequency attributes F. Based on the ratings chosen for these attributes.4.6 of Appendix D.0 0.5 x 1. pdelayed. using the ignition probability scores for attributes A.5 as follows: p delayed = 1 .k (b J + b K + b L + b M ) b A b Bb E = 1 .0 Table F. as follows (noting that pimmediate = bG): p ignition = 1 .e .0 + 0. is then calculated from equation D.0 0. J.2 1.5 1. sources Control deliberate ignition Chosen rating HFL Average Poor Average Poor Poor Poor Poor Corresponding score bA bB bE bG bJ bK bL bM 1. The probability of delayed ignition of the release. is calculated from equation D. the corresponding scores are taken from Table D.4.0. the corresponding scores are taken from Table D.(1 .0.3 Scores for ignition probability attributes The probability of delayed ignition of the release. Section D. L and M.5 c A c Bc E (1 + c N ) = 0.3 Table F. E.3 + 0.3) x 1.6. Attribute A B E G J K L M Material classification (flash point) Release quantity Spill and vapour control Safety management Control fixed ignition sources Control static ignition Control misc. B. E and N.5 x1.p immediate ) (1 .4 Probability of injury or fatality (F.0 0. using the probability of injury of fatality scores for attributes A. pdelayed.85 (F. B.0 1.7 x 1.2 x (1.3 0.2) (1 . Section D. as follows: p injury = 0. Based on the ratings chosen for these attributes.3 Probability of ignition The probability of ignition is calculated using equations D. is calculated from equation D.3 and D.2) The probability of ignition of the release.Attribute C D F G H I Frequency of use Containment Housekeeping Safety management Staff awareness Maintenance and inspection Chosen rating Regular Poor Poor Average Poor Poor Corresponding score aC aD aF aG aH aI 30 1.5 1.3) The probability of injury or fatality is calculated using equation D.0 = 0.5 of Appendix D. K.0 x 0.3 0.0 x (1 + 0.2 and are given in Table F.595 56 (F.0 x 0.3 + 0. pignition.3 and are given in Table F.85) = 0.7) = 0.878 F.0 1.
Attribute A B E N Material classification (flash point) Release quantity Spill and vapour control Proximity of staff Chosen rating HFL Average Poor Average Corresponding score cA cB cE cN 1. Section D.2 and F.5) 57 .5 Calculation of risk Finally.7 1. respectively) using equation D. and probability of injury or fatality. p injury = 15 x 0. p ignition .7 Table F. for the workplace is calculated as the product of release frequency. f. pignition. the notional risk.1.1: R = f release . (calculated in Sections F.3.1 of Appendix D.0 0. pinjury. probability of ignition. F.0 0. R.4 Scores for probability of injury or fatality attributes F.595 = 7.868 x 0.75 (F.
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