LEV Central

The Knowledge Base for LEV

OXYL8 Captor Hood Calculation Apps for iPhone and Android

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OXYL8 have developed a free LEV App for Android and iPhones which will (using Fletcher’s Equations) calculate the Hood Entry Velocity required for any shape of Captor Hood. For the moment the App equations can only be run backwards eg to determine Captor Distance for round or square Captor Hoods but we have an update…

Measuring Aerosols in Air

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Occasionally there may be a need to measure aerosol particulates in air and there are instruments to do this ….. but they work on two fundamentally different ways.  This article by TSI guides you through the differences and might assist you to select the best option for your application. The article provides a basic understanding…

Video – “How to Measure Captor Hood Control Distance?”

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Latest OXYL8 LEV training video (Sept 17) on YouTube discusses the ways in which we can approach the verification of the Control Distance of a particular Captor Hood. More usually we use smoke release on the centreline out from the hood face until the first ‘whisp’ of smoke is not controlled.  From there most surveyors…


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Second Edition, Published by HSE 2011 This is HSE’s current guide on LEV and related topics.  Here you will find recommended Duct Velocities, Captor Velocities, Face Velocities, and other design criteria. The various types of hoods, filters, fans and discharges are all described. Sections on Manuals and Log Books, LEV Examination and Testing protocols and…

BS EN 12021:2014 Respiratory Equipment – Compressed Gases for Breathing Equipment

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This British Standard will be very useful to anyone undertaking quality/safety testing of compressed air used to supply – Respiratory protective devices – compressed air line breathing apparatus. Purchase a copy of the Standard here:- BS EN 12021: 2014

HSE Video of Smoke Clearance Testing – Smoke Dispersal in Spray Room

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Short video produced by HSE showing (in fast play mode) the dispersal of smoke in an average Spray Room during clearance testing. Video can be viewed here: HSE Smoke Clearance Video Smoke generators may be purchased here:

Paint Booth Clearance Times – Smoke Testing HSE

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This HSE Research Report from 2006 reviews commercially available (party) smoke machines which could be used for determining the clearance times of paint spray booths. ” ……….. Seven different fog machines were tested for assessing the clearance times of spray booths and rooms, the results were compared to the Colt 4 smoke generator currently used by…

BOHS P600 Foundation Course – Methods for Testing Performance of LEV

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In early 2017 BOHS launched their new Foundation course in the P600 series for LEV.  This one has in fact been given the title P600.  Although it is in the “P” series this one-day course is in fact a Foundation module and it is intended to give delegates an introduction to LEV systems and, more…

Video – “How to Use the PITOT Tube”

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New OXYL8 training video on YouTube which provides an excellent introduction to the PITOT Tube, how to make the connections to a Manometer and how to take correct readings in a duct How to Use the PITOT Tube