{"product_id":"lev108-guide-on-reverse-jet-filters-copy","title":"LEV107 - Basic LEV maths (v1.4)","description":"\u003cp data-start=\"405\" data-end=\"567\"\u003eMathematics sits at the heart of every effective Local Exhaust Ventilation (LEV) system — yet it’s one of the areas that causes the most uncertainty in the field.\u003c\/p\u003e\n\u003cp data-start=\"569\" data-end=\"941\"\u003eFrom duct sizing and airflow calculations to understanding velocity, pressure, and density, LEV maths quietly determines whether a system \u003cstrong data-start=\"707\" data-end=\"728\"\u003econtrols exposure\u003c\/strong\u003e or merely looks like it should. And when the maths is misunderstood — or skipped altogether — the consequences show up quickly: poor capture, unstable systems, failed examinations, and unnecessary risk to health.\u003c\/p\u003e\n\u003cp data-start=\"943\" data-end=\"994\"\u003eLEV107: Basic LEV Maths was written to change that.\u003c\/p\u003e\n\u003cp data-start=\"996\" data-end=\"1252\"\u003eThis guide strips LEV mathematics back to its engineering fundamentals, explaining not just \u003cem data-start=\"1088\" data-end=\"1094\"\u003ewhat\u003c\/em\u003e to calculate, but \u003cem data-start=\"1113\" data-end=\"1118\"\u003ewhy\u003c\/em\u003e those calculations matter and \u003cem data-start=\"1149\" data-end=\"1156\"\u003ewhere\u003c\/em\u003e they apply during design, testing, and COSHH Regulation 9 Thorough Examination and Test (TExT).\u003c\/p\u003e\n\u003chr data-start=\"1254\" data-end=\"1257\"\u003e\n\u003ch2 data-start=\"1259\" data-end=\"1314\"\u003eA Practical Engineering Guide — Not a Maths Textbook\u003c\/h2\u003e\n\u003cp data-start=\"1316\" data-end=\"1383\"\u003eLEV107 is not academic maths and it’s not theory for theory’s sake.\u003c\/p\u003e\n\u003cp data-start=\"1385\" data-end=\"1552\"\u003eIt’s a \u003cstrong data-start=\"1392\" data-end=\"1441\"\u003efield-focused, metric-based engineering guide\u003c\/strong\u003e, written specifically for LEV practitioners who need to apply calculations confidently during real-world work.\u003c\/p\u003e\n\u003cp data-start=\"1554\" data-end=\"1622\"\u003eInside, you’ll find clear explanations and worked examples covering:\u003c\/p\u003e\n\u003cul data-start=\"1624\" data-end=\"2088\"\u003e\n\u003cli data-start=\"1624\" data-end=\"1685\"\u003e\n\u003cp data-start=\"1626\" data-end=\"1685\"\u003eMathematical terms used in LEV — explained without jargon\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1686\" data-end=\"1738\"\u003e\n\u003cp data-start=\"1688\" data-end=\"1738\"\u003eWorking correctly in metres (and why it matters)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1739\" data-end=\"1776\"\u003e\n\u003cp data-start=\"1741\" data-end=\"1776\"\u003eCircles, areas, and duct geometry\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1777\" data-end=\"1816\"\u003e\n\u003cp data-start=\"1779\" data-end=\"1816\"\u003eCalculating duct diameter from area\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1817\" data-end=\"1858\"\u003e\n\u003cp data-start=\"1819\" data-end=\"1858\"\u003eThe Velocity–Volume–Area relationship\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1859\" data-end=\"1913\"\u003e\n\u003cp data-start=\"1861\" data-end=\"1913\"\u003eStatic, velocity, and total pressure relationships\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1914\" data-end=\"1952\"\u003e\n\u003cp data-start=\"1916\" data-end=\"1952\"\u003eVelocity pressure and air velocity\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1953\" data-end=\"2005\"\u003e\n\u003cp data-start=\"1955\" data-end=\"2005\"\u003eStandard and non-standard air density conditions\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2006\" data-end=\"2038\"\u003e\n\u003cp data-start=\"2008\" data-end=\"2038\"\u003ePractical correction factors\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2039\" data-end=\"2088\"\u003e\n\u003cp data-start=\"2041\" data-end=\"2088\"\u003eCommon conversion factors used in LEV testing\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"2090\" data-end=\"2235\"\u003eEach section builds logically, helping you understand how individual calculations link together to form a complete picture of system performance.\u003c\/p\u003e\n\u003chr data-start=\"2237\" data-end=\"2240\"\u003e\n\u003ch2 data-start=\"2242\" data-end=\"2266\"\u003eWhy LEV Maths Matters\u003c\/h2\u003e\n\u003cp data-start=\"2268\" data-end=\"2345\"\u003eLEV systems don’t fail randomly — they fail because the numbers don’t add up.\u003c\/p\u003e\n\u003cp data-start=\"2347\" data-end=\"2435\"\u003eCommon issues seen during TExT often trace back to basic mathematical misunderstandings:\u003c\/p\u003e\n\u003cul data-start=\"2437\" data-end=\"2757\"\u003e\n\u003cli data-start=\"2437\" data-end=\"2508\"\u003e\n\u003cp data-start=\"2439\" data-end=\"2508\"\u003eDuct velocities that look acceptable but are calculated incorrectly\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2509\" data-end=\"2563\"\u003e\n\u003cp data-start=\"2511\" data-end=\"2563\"\u003eFlowrates that don’t align with hood design intent\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2564\" data-end=\"2633\"\u003e\n\u003cp data-start=\"2566\" data-end=\"2633\"\u003ePressure readings that are misinterpreted or compared incorrectly\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2634\" data-end=\"2693\"\u003e\n\u003cp data-start=\"2636\" data-end=\"2693\"\u003eHot air systems assessed using standard air assumptions\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2694\" data-end=\"2757\"\u003e\n\u003cp data-start=\"2696\" data-end=\"2757\"\u003eFan performance judged without understanding total pressure\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"2759\" data-end=\"2937\"\u003eLEV107 helps practitioners recognise these issues early, giving you the confidence to question results, validate performance, and justify your conclusions clearly and defensibly.\u003c\/p\u003e\n\u003chr data-start=\"2939\" data-end=\"2942\"\u003e\n\u003ch2 data-start=\"2944\" data-end=\"2968\"\u003eWho This Guide Is For\u003c\/h2\u003e\n\u003cp data-start=\"2970\" data-end=\"2990\"\u003eLEV107 is ideal for:\u003c\/p\u003e\n\u003cul data-start=\"2992\" data-end=\"3169\"\u003e\n\u003cli data-start=\"2992\" data-end=\"3021\"\u003e\n\u003cp data-start=\"2994\" data-end=\"3021\"\u003eLEV engineers and testers\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3022\" data-end=\"3049\"\u003e\n\u003cp data-start=\"3024\" data-end=\"3049\"\u003eOccupational hygienists\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3050\" data-end=\"3078\"\u003e\n\u003cp data-start=\"3052\" data-end=\"3078\"\u003eDesigners and installers\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3079\" data-end=\"3108\"\u003e\n\u003cp data-start=\"3081\" data-end=\"3108\"\u003eTrainee LEV practitioners\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3109\" data-end=\"3169\"\u003e\n\u003cp data-start=\"3111\" data-end=\"3169\"\u003eAnyone involved in COSHH compliance and exposure control\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"3171\" data-end=\"3342\"\u003eWhether you’re new to LEV or looking to strengthen your technical foundation, this guide provides the maths you actually use — explained in a way that finally makes sense.\u003c\/p\u003e\n\u003chr data-start=\"3344\" data-end=\"3347\"\u003e\n\u003ch2 data-start=\"3349\" data-end=\"3367\"\u003eProduct Details\u003c\/h2\u003e\n\u003cul data-start=\"3369\" data-end=\"3609\"\u003e\n\u003cli data-start=\"3369\" data-end=\"3407\"\u003e\n\u003cp data-start=\"3371\" data-end=\"3407\"\u003e\u003cstrong data-start=\"3371\" data-end=\"3381\"\u003eTitle:\u003c\/strong\u003e LEV107: Basic LEV Maths\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3408\" data-end=\"3438\"\u003e\n\u003cp data-start=\"3410\" data-end=\"3438\"\u003e\u003cstrong data-start=\"3410\" data-end=\"3422\"\u003eEdition:\u003c\/strong\u003e Third Edition\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3439\" data-end=\"3474\"\u003e\n\u003cp data-start=\"3441\" data-end=\"3474\"\u003e\u003cstrong data-start=\"3441\" data-end=\"3452\"\u003eFormat:\u003c\/strong\u003e Digital guide (PDF)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3475\" data-end=\"3518\"\u003e\n\u003cp data-start=\"3477\" data-end=\"3518\"\u003e\u003cstrong data-start=\"3477\" data-end=\"3487\"\u003eFocus:\u003c\/strong\u003e Metric-based LEV mathematics\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3519\" data-end=\"3550\"\u003e\n\u003cp data-start=\"3521\" data-end=\"3550\"\u003e\u003cstrong data-start=\"3521\" data-end=\"3530\"\u003eISBN:\u003c\/strong\u003e 978-1-9192558-0-4\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3551\" data-end=\"3585\"\u003e\n\u003cp data-start=\"3553\" data-end=\"3585\"\u003e\u003cstrong data-start=\"3553\" data-end=\"3564\"\u003eAuthor:\u003c\/strong\u003e Louise Davies Wood\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3586\" data-end=\"3609\"\u003e\n\u003cp data-start=\"3588\" data-end=\"3609\"\u003e\u003cstrong data-start=\"3588\" data-end=\"3602\"\u003ePublished:\u003c\/strong\u003e 2025\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"LEV Academy","offers":[{"title":"Default Title","offer_id":52699537441107,"sku":null,"price":15.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1017\/3313\/8771\/files\/Screenshot_2026-01-29_121226.png?v=1769688774","url":"https:\/\/www.levacademy.co.uk\/products\/lev108-guide-on-reverse-jet-filters-copy","provider":"LEV Academy","version":"1.0","type":"link"}