When a team from the Fire and Rescue Service are called to an incident at an industrial premises (such as a warehouse, a production plant, or on a highway or railway), one must consider the presence of materials that could act as accelerants for a fire to take hold. The presence of dangerous goods must be checked, when a plan of action is formulated, and the risk(s) assessed in order to restore order.
A well-managed industrial site or depot must have a mandatory fire-risk assessment which references an up-to-date site plan. The schematic indicates the locations of raw materials, finished product and ‘goods-in-work’ inventories. Some of these products may present CBRNE (Chemical, Biological, Radiological, Nuclear & Explosive) as well as physical hazards. In the UK these products are termed ‘dangerous goods’.
If quantities of dangerous goods are significant, then the premises may well be governed by COMAH regulations (Control of Major Accident Hazards). One aspect in the application of COMAH to a site is the designation in terms of overall quantity (tonnage) stored within that site of both: (a) ‘named substances’ (specific chemicals or ‘agents’ that pose high risk due to their nature and/or properties, e.g. unstable organometallics used in semi-conductor fabrication such as tungsten hexa-Fluoride WF6) or highly toxic material such as carbonyl chloride (aka phosgene); and (b) total tonnage per Kemmler risk category and SDS Risk Phrase.
The threshold limits are split into Lower and Higher Tier COMAH, depending upon quantities stored on the site. This legislation ensures health, safety, environmental and security considerations are factored for the site staff, visitors and contractors, as well as local residents, emergency responders and the general public, e.g. ‘society’.
Dangerous goods are denoted within ADR* (and IMDG**) using Kemmler classification as:
Class 1 – Explosive substances or articles
Class 2 – Gases
Class 3 – Flammable liquids
Class 4.1 – Flammable solids, self-reactive and de-sensitized explosives
Class 4.2 – Substances liable to spontaneously combust
Class 4.3 – Substances which in contact with water emit flammable and/or toxic gas
Class 5.1 – Oxidizing substances
Class 5.2 – Organic peroxides
Class 6.1 – Toxic
Class 6.2 – Infectious substances
Class 7 – Radioactive
Class 8 – Corrosive
Class 9 – Miscellaneous dangerous substances and environmentally hazardous
But even if the site is below COMAH thresholds, a well-managed industrial complex or depot will have risk assessments, inventory checks and site schematics in the event of an incident (especially fire as well as security-risk assessments). If the incident occurs on a public highway, or railway, ADR regulations have a protocol that should be followed, with help from the consignor’s DGSA (Dangerous Goods Safety Advisor). Within the ADR regulations are areas of help for the emergency responders, especially the police, ambulance and most critically the men and women of the Fire and Rescue Service (FRS).
I have many colleagues within Fire and Rescue in the UK, and in Hong Kong, as well as within the various agencies that make up the ‘blue-light’ teams who are tasked to restore order following an ‘incident’ – so I will be providing insight into the chemistry that should be considered when making both a dynamic risk assessment, as well as an action plan to restore order and protect the responders.
These notes are not restricted to depots (operating sites) but apply also to our road and rail networks that FRS will be required to attend, should an incident occur. I will be focusing on the chemistry behind the incident.
It was thanks to Jeff Hart OBE (now retired) of the Department for Transport (DfT), Clive Dennis (now retired) of the Health and Safety Executive (HSE), Nick Bailey of Braemar Howells, Adam Shefras of Arthur J. Gallaher (formerly OAMPS Petrochemical) Insurance and, most critically, my very dear and long-standing friend Richard Shreeve of Labeline Ltd who was working for the National Chemical Emergency Centre (NCEC) at the time – in helping me setting-up www.hers-info.co.uk – an emergency response facility to assist FRS when an incident involving packaged chemicals occurred, within the Hazchem Network’s UK depot structure.
This first column focuses upon what is termed as ADR Hazard Class Three: Flammable Liquids. In later columns I hope to focus upon the other classes, drawing upon my real-world experience and technical background as an industrial chemist managing chemical incidents and dangerous situations.
In my last year as Managing Director of Hazchem Network (in 2018]) I came to review the preceding 12 months’ throughput activity with our Dangerous Goods Safety Advisor (DGSA) John Newsome, for our annual audit and report.
Neither of us were surprised to see that of all nine classes of dangerous goods as defined under ADR and IMDG regulations, Class 3 (Flammable Liquids) represented over 40% (in terms of tonnage shipped) of our throughput of pallets distributed by the hub-and-spoke nature of Hazchem Network’s Depot Infrastructure (UK, Ireland and Mainland Europe).
It was a déjà vu moment for me, as I recall carrying out a similar analysis on the tanker fleet I oversaw as Operations Director of Interoute Transport Service’s Chemical Road Tanker Operation. Again, Class 3 (Flammable Liquids) were the largest ADR class we carried in bulk, which in tonnage terms was well over half of our total carrying capacity.
When comparing other ADR classes carried, both in Bulk Tankers as well as Packaged within Pallets/Parcels; Class 8 Corrosive Liquids and Class 9 Environmentally Hazardous Liquids (and Miscellaneous) make up approximately 20% each.
While the other ADR Classes, such as Gas (Class 2); Reactive/Flammable Solids & Dangerous when Wet products (Classes 4.1, 4.2 & 4.3); Oxidising Agents & Organic Peroxides (Classes 5.1 & 5.2) and Toxic Products (Classes 6.1) make up the balance of approximately 20%.
So, my experience in both bulk as well as packaged dangerous goods supply chains approximates the UK road network with the following splits of dangerous goods as regulated under ADR.
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%
Due to issues related to security I have not included information regarding the carriage of Class 1 (Explosive), Class 6.2 (Biologically Infectious) or Class 7 (Radioactive); besides, these have specific regulations and, apart from selected 6.2 products, cannot be mix-loaded with other ADR Classes.
Also tonnages of DG shipped under the Limited Quantity Regulations for retail use, such as nail varnish, aerosols (such as ‘Mr Sheen’), oven cleaners etc. have not been included – as when shipped under LQ Derogations, the hazard classes are not permitted to be denoted on external carriage labelling, or manifested within the delivery paperwork.
ADR Class 3 Flammable Liquids both in bulk tankers as well as packaged/palletised products (contained within IBCs, drums and cans) constitute the largest tonnage of dangerous goods shipped on UK Roads.; hence this first column addresses this class.
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 in contact with an ignition source (or heat), with oxygen present. If you recall ‘the fire triangle’, in order for a fire to start, you require:
- A source of fuel
- Heat or a naked flame, or spark
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 the 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). Incidentally the title of Ray Bradbury’s 1953 dystopian masterpiece Fahrenheit 451 references the autoignition point of paper (233°C). This novel places personnel from FRS to actually set fires (of books) rather than extinguish them.
The fire point is higher than the flash point because at the flash point, more vapor 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 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.
In terms of refined petroleum from distillation, we see that petrol/gasoline is PG I as it is the most flammable (and therefore the most problematical in a release or leakage situation), while diesel/derv is of a lower hazard, due to its higher initial boiling point and higher flash point. Jet fuel (aka Jet A1), which is within the kerosene fraction, resides between the two ‘cuts’ (gasoline to diesel).
In practical terms, a spillage of petrol (aka gasoline/motor spirit) is far, far more worrying than a spillage of diesel in terms of risk of catching fire from a spark or heat due to the higher flash point of PG III. Even in Siberia, a spillage of petrol poses a risk of fire, even on ice, while a diesel spillage in sub-zero temperatures forms a petroleum jelly/wax, one that is unlikely to ‘flash’ due to low ambient temperatures (below Diesel’s FP).
So, with fuels, solvents, oils, surface-coating products (including paints, varnishes, adhesives), cleaning products, alcohols, ethers, lacquers et al derived from petroleum refining, we can understand why Class 3 makes up such a large proportion of dangerous goods on our roads, close to half of all ADR products.
Because of Class 3, and the preponderance of flammable liquids that form part of our society, we have to have a robust Fire and Rescue Service on standby at all times, and this is why fire-risk assessments are mandatory for all industrial organisations, and why many general logistics companies (including parcel carriers) are now refusing to carry Class 3, as it falls under ADR regulations, as they realise the problems posed, including insurance and staff welfare.
If you require training or assistance with the practical aspects of the chemistry of dangerous goods, please feel free to contact me.
I have over 30 years’ experience of dealing with chemicals and gas in a production and road transport environment at a senior management level in the UK and overseas with Interoute Transport Services, Linde Gas UK Ltd, United Transport, Inspectorate International (Saudi Arabia) and Transport Development Group (TDG). I was the co-creator and co-founder of Hazchem Network Ltd, and Managing Director of the business for over a decade. If I can’t assist, I will know someone who can.
For more information, email email@example.com
*ADR = Accord Dangereux Routier (European regulations concerning the international transport of dangerous goods by road). It is a UN treaty concluded in 1957 and updated ever since, according to new rules and regulations in the logistics industry.
**IMDG = International Maritime Dangerous Goods Code is accepted by MSC (Maritime Safety Committee) as an international guideline to the safe transportation or shipment of dangerous goods or hazardous materials by sea and waterway.