ask 3: LEV effectiveness According to HSG 258 (A guide to local exhaust ventilation) a local exhaust ventilation (LEV) thorough examination and test (TExT) involves three stages. The first of these three stages is a 'visual and structural examination' of the LEV. (a) (i) Based on the scenario only, what indicators suggest that there may be a problem with the LEV system? (8) (ii) What else should those carrying out the TExT do during this first stage? The second stage of the LEV TExT is a review of the technical performance; this includes measuring. In the diagram in supporting document 3 , three possible locations (marked X,Y and Z ) for measuring duct velocity are shown. (b) (i) What features make a suitable location for measuring duct velocity? (4) (ii) Discuss the suitability of EACH of these test locations when measuring duct velocity. Note: You must discuss locations X,Y and Z in your answer. (c) Identify FOUR measurements, other than duct velocity, that could be made during the second stage of the LEV TExT. (4) One of the recommendations made in the recent LEV TExT report is to change the current design of the LEV at the mixing vessel charging points. The current and recommended designs are shown in supporting document 4. (d) Explain how the recommended new LEV design, shown in figure 2 of supporting document 4 , will help to reduce the exposure of workers when working at the mixing vessel charging point. (18) Note: You should support your answer, where applicable, using relevant information from the scenario and the relevant supporting document