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LOCAL EXHAUST VENTILATION | GUIDANCE Figure 1: The TR40 guidance has a clear, diagrammatic description of the roles and responsibilities of those involved in delivering LEV The designer should have proven competencies in the fields of occupational hygiene and LEV engineering design what to ask when evaluating LEV tenders and quotations. It explains that the employer must ensure their advisers, and those they employ for specific roles to undertake works associated with LEV systems, are competent. The guidance outlines the competencies required for LEV designers suppliers, commissioning engineers, maintenance engineers, installation contractors (mechanical, electrical and specialist), and the thorough examination and test engineer. For example, the designer should be able to demonstrate competence in designing effective LEV systems. They should be a member of a relevant professional body and have proven competencies in the fields of occupational hygiene and LEV engineering design. It also explains the role of the occupational hygienist if a risk assessment is deemed necessary to monitor employees exposure to hazards and evaluate the performance of control measures in place. There are questions employers should ask members of the supply chain. For example, how did the designer show that the LEV provided adequate control, and have there been any operational issues since installation. Section 4 features the employer brief and design parameters. The brief for the designer contains the requirements for the system. The designer should visit the site to observe the operation of the process if possible and this may influence the control options available. Section 5 features a checklist for the LEV system specification. There are 26 items, including: details of the processes and hazardous substances to be controlled; the agreed controlled benchmark to be achieved, with the relevant occupational exposure limits; and information about hoods, ductwork, test points, filter, air mover and motor, controls, make-up air and maintenance access. Evaluating LEV tenders and quotations is in section 6. The key guarantee required is that the LEV will adequately control the hazardous substance to an agreed benchmark. Other areas to check are the competency of the LEV supplier, specification and installation compliance, essential documentation, and whole-life system costs. There are sections on installing, commissioning and maintenance, and TR40 explains how LEV commissioning differs from normal plant commissioning, as it has to ensure the operators safe use of the system. Section 7 describes the installation programme, and states that an outline project programme should be developed to identify key tasks, critical dates and milestones. Best practice for an operations and maintenance manual is described in Section 8, while Section 9 focuses on how commissioning should be carried out. It says the report should include measured exposures from the breathing zone of the operator to identify whether the LEV: is controlling exposure to the hazardous substance adequately; is matching the specification; has been correctly installed; and is being used correctly. The final four sections discuss training, the log book, handover documents and thorough examination and testing. TR40 should be read in conjunction with the HSE publication HSG258 Controlling airborne contaminants at work A guide to local exhaust ventilation, which offers employers further guidance on the design of new local exhaust ventilation (LEV) equipment. TR40: A guide to good practice for local exhaust ventilation is available from the CIBSE Knowledge Portal at bit.ly/CJSep20Lev CJ PEOPLE DIE IF YOU DONT GET THE DESIGN RIGHT Adrian Sims is passionate about raising the profile of local exhaust ventilation. As an expert witness in HSE prosecutions, he has seen the devastating effects on peoples health when organisations fail to provide adequate protection from the inhalation of hazardous substances. In a recent case, a former soldier inhaled oil mist while at work on one occasion, resulting in a serious respiratory condition that led to him losing his flat and girlfriend. Thats how serious this is it destroys lives, says Sims. TR40 is designed for people in the LEV contract chain. HSE already has a guidance document, HSG258, aimed at the owner of the system; TR40 looks at how designers, installers and commissioning engineers protect the person at risk. When you look at occupational exposures and who gets hurt, it tends to be the lowskilled worker, who doesnt know that wood dust gives you cancer, says Sims. A huge education piece has to be done, from top to bottom. It needs to be treated with care. If we dont get the design right, people die. Sims says he is asked by contractors to design LEV systems without being told exactly what is having to be extracted from the space. They say its just an extraction system, just get on with it. They dont appreciate the issues. Wood dust gives people cancer its an asthmagen and a carcinogen. ADRIAN SIMS is managing director at Vent-Tech and director at WorkSafe Design 30 September 2020 www.cibsejournal.com CIBSE September 2020 p29-30 TR40 Guide.indd 30 21/08/2020 14:51