Truck and Track Autumn 2026 www.truckandtrack.com 66 DANGEROUS GOODS the nominal 21% Oxygen level in the atmosphere has additional concerns. a. The increase of fire hazard, as Oxygen aids combustion. An atmosphere enriched with Oxygen will ignite faster, as the O2 % level rises. b. A narcotic effect upon humans occurs when the atmosphere is enriched with O2 and has serious implications to life if abnormally high. c. Increased risk of Oxidation reactions with substrates that the O2 may come into contact with. d. Cryogenic burns with LOX as liquid O2 has a Boiling Point of -183 Degrees Celsius. e. Inadvertent pressure release from Cylinder/Cryogenic Vessel Exothermic Reaction The risk of chemical (and physical) reactions with the presence of Oxygen gas may seem obvious when we see it used in combination with Acetylene in welding/cutting (Oxy-Acetylene). BUT we must understand the risk of runaway or uncontrolled reactions can occur with compounds that contain Oxygen. These are referred to as Class 5.1 Oxidising Agents, or even more reactive 5.2 Organic Peroxides. The ADR carriage and usage symbol for 5.1 Oxidising Agents gives a clue to the risk – the black flames on the yellow-diamond arise from the symbol for Oxygen (O). Some class 5.2 Organic Peroxides are so reactive, that they require stabilisers/inhibitors and some can only be stored or travel by temperature control (kept refrigerated to reduce the evolution of the Oxygen, they contain). Both class 5.1 and 5.2 react adroitly with organic matter, such as hydrocarbons, (materials that contains both Hydrogen, Carbon and in some cases, Nitrogen), such as (petroleum derived) Oils and Gases, skin tissue, greases, lubricants etc. I have yet to see a road, transport yard that is free from oil stains on the ground, in-fact some road surface material contains hydrocarbon within the bitumen or asphalt formulation. Under certain conditions, an exothermic reaction can readily take place between Class 5.1 and 5.2 with Class 3 or 4, hence the maxim (from ADR Diamond label colour) ‘Red and Yellow do not mix’. An exothermic reaction is one that generates heat; the opposite to an endothermic reaction. If the heat is not dissipated, this leads to fire and can result in a thermal run-away, aka an Explosion. Common compounds that contain Oxygen used in industry are Class 2 Nitrous Oxide (and mixtures of 50/50 Nitrous Oxide and Oxygen, the so called laughing gas or pain-relief Entonox), Fertilizer products such as Class 5.1 and derivatives of Class 5.2 Ammonium Nitrate* and Potassium Nitrate, cleaning products, disinfectants, bleaches, paint-related products, etchants - as well as haircare, mouthwash and skin products that contain Hydrogen Peroxide (and its related compounds). *Ammonium Nitrate was tragically seen as the source of the catastrophic explosion in Beirut, Lebanon on 5th August 2020. The concerns regarding hygiene are showing growth in supplychain volumes of cleaning/disinfecting products that contain Oxygen, and therefore of an Oxidising nature (5.1) as well as Organic Peroxides (5.2). This is in part due to the advent of Coronavirus (COVID-19) across the globe, not just in terms of cleaning products but also as Class (2) where Oxygen therapy TRUCK & TRAILER SOLUTIONS WELCOME TOALLPORTS GROUP allportsgroup.co.uk Emergency Response Vehicle ADR transport desk
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