Truck and Track Spring 2024

Truck and Track Spring 2024 www.truckandtrack.com 62 DANGEROUS GOODS The current UK Road Network carries the following approximated splits of bulk and packaged Dangerous Goods under ADR as being: Class 3 Flammable Liquids ~ 40% Class 8 Corrosive Liquids ~ 20% Class 9 Environmentally Hazardous/ Miscellaneous ~ 20% Classes 2, 4.1, 4.2, 4.3, 5.1, 5.2 and 6.1 make up the balance of ~ 20% However, there is growth in Class 9, as more material becomes classified as dangerous to the environment. Note – there are also flammability risks in some gases (Class 2), solids (Class 4) as well as within oxidising materials (Class 5.1 and 5.2). Due to issues related to security, I have not included information regarding the carriage of Class 1 (Explosive), Class 7 (Radioactive) and Class 6.2 (Biologically Infectious). Classes 1 and 7 (and some selected Class 6.2) cannot be mix-loaded with other ADR Classes for obvious reasons. Also, tonnages of DG shipped under the Limited Quantity Regulations (LQ) for retail domestic and automotive use, such as Nail Varnish, Aerosols, Cleaning Products etc, have not been included. ADR Class 3 Flammable Liquids both in Bulk Tankers, as well as Packaged/Palletised products (contained within IBCs, Drums, Cans and Parcels), constitute the largest tonnage of categorised Dangerous Goods shipped on UK Roads. Let’s consider the physics and chemistry of Class 3, flammable liquids: Firstly, we need to understand the term Flash Point The Flash Point is the lowest temperature at which vapours of a volatile material will ignite, when given an ignition source, with Oxygen present. If you recall ‘the fire triangle’, in order for a fire to start, you require – (a) A source of fuel (b) Heat or a naked flame, or spark (c) Oxygen We are ignoring Pyrophoric Material such as Silicon Tetrahydride (SiH4) which, if released, can catch fire without heat or a spark, due to reactivity with atmospheric Oxygen. The Flash Point is often confused with – Fire Point (the lowest temperature at which vapour of the material will keep burning after the ignition source is removed) and Autoignition Point (the temperature that results in spontaneous autoignition) The fire point is higher than the flash point because, at the flash point, more vapour may not be produced rapidly enough to sustain combustion. Neither flash point nor fire point depends directly on the ignition source temperature, but ignition source temperature is far higher than either the flash or fire point. As a young chemist working in the petroleum industry, I often measured Flash Points of liquids (with ASTM/IP methods by Pensky-Martens apparatus) as it is a key metric in the classification of flammable liquids. Once classified as either non-flammable, low flash or high flash in terms of flammability, we can then risk assess the activity, in order to determine a safe system of work (SSoW) for storage/carriage (logistics). But we also have to determine the extent of the flammability of the volatile liquid. A flammable liquid is a volatile fluid that has a flash point at ambient (or at a lower) temperature; but one that does not exceed 60°C (at atmospheric pressure). To determine the level of risk in terms of relative flammability of Class 3, we use transport category/packing groups (to further subdivide Class 3) hence why Packing Group I is the highest relative risk (lowest flash point/easier to ignite). The Carriage of Flammable Liquids within the DG Supply Chain by Ali Karim Ali Karim In this issue, our Dangerous Goods Columnist, Ali Karim FRSC CChem provides an updated insight into the largest ADR Class of Dangerous Goods carried on our road network – Flammable Liquids – together with guidance to ensure that your site/operation complies with current legislation. TRUCK & TRAILER SOLUTIONS WELCOME TOALLPORTS GROUP allportsgroup.co.uk

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