1. Class 3 5.2 Flammable/inflammable Liquid / vapour Fuel / solvent
5.2 Preventative and safety measures appropriate to the various types of hazards – Class 3
Examination Questions: 15
2 x 45min Teaching units Initial
1 x 45min Teaching Unit Refresher
5.2.1 Characteristics of Class 3 substances
Explain: That “flammable” (or alternatively the synonymous term inflammable) means “will burn”, so flammable/inflammable liquid may be described as ‘a liquid which will burn’.
However liquids do not themselves burn – it is the vapour that the liquids give off which (when mixed with air or oxygen) actually burn. Thus a more accurate definition of a flammable liquid is “a liquid which gives off a flammable vapour”.
State: That Class 3 Substances make up more than 50% of all dangerous substances moved in the UK by road.
Explain: That flammable liquids may be broadly divided into two categories.
Liquid fuels: most of these are derived from petroleum; examples are petrol, kerosene, diesel/gas oil/heating oil.
Liquids used as solvents, and as raw materials in the manufacture of other chemicals. Some examples are methanol, ethanol, acetone and toluene.
Display: The flammable liquid hazard label and draw attention to its features (colour, flame symbol, etc).
ELEVATED TEMPERATURE LIQUIDS FLAMMABLE
Explain: That some substances although they may have a flash point above 60ºC could be classified as Class 3 substances because of the high temperature at which they are carried. Also if they are carried at or higher than the flash point, great care must be taken to ensure the vapours do not come into contact with a source of ignition. These substances are assigned to UN3256 (ELEVATED TEMPERATURE LIQUID, FLAMMABLE, N.O.S., with flash point above 60ºC, at or above its flashpoint).

2. Danger Label 5.2 5.2.2 Danger labels, marking and placards
Show: Class 3 placard
Explain: The text may be shown in black or white. The class number must be shown in the bottom corner. All labels must be able to withstand open weather conditions without a substantial reduction in effectiveness. For packages the minimum size is 100mm x 100mm for vehicles 250mm x 250mm all labels must be placed at an angle of 45 to form a diamond shape.

3. Dangers 5.2 Fire Fire Triangle Precautions
5.2.3 Dangers and precautions to be exercised when transporting flammable liquids
Dangers - FIRE
Revise: The three ingredients necessary for fire, and the fire triangle (see core module notes)..
Remind: Drivers that the main hazard of flammable liquids is that they give off vapours which when mixed with air form ignitable mixtures.
State: That a fire or explosion occurs if a source of ignition is introduced into such a mixture.   
Remind: Drivers that it is the vapours from flammable liquids, which burn when mixed with oxygen.
PRECAUTIONS
Summarise: Precautions to avoid spillage and ensure safe containment for tanker and tank container drivers.
Ensure all hose connections are properly and securely made before loading or unloading.
Securely close all valves, manlids, etc. after completion of loading or unloading.
Ensure tank compartments are not overfilled (remember ullage requirements)
Drain all hoses after loading or unloading.
Ensure end-caps are fitted to hoses that are not being used where appropriate.
Strictly observe all laid-down procedures at loading and unloading points.
Summarise: The precautions to avoid spillage and ensure safe containment for packaged goods drivers:
Do not accept any leaking or significantly damaged receptacles.
Check that all receptacles and packages are safely loaded and securely stowed.
Report any leaks (however small), which develop during the journey.

4. Volatility 5.2 Volatile liquids easily turn to vapour 5.2.4 Volatility
Define: Volatility is the readiness with which a liquid changes to vapour, i.e. the readiness with which a liquid evaporates.
Explain: That volatility is an important factor affecting the flammability of a liquid, and that in general, high volatility goes hand-in-hand with low flash point.

5. Vapour 5.2 Vapour mixes with Oxygen above liquid May be ignited
5.2.5 Vapours above the liquid burn
Emphasise: That it is the vapour from the flammable liquid – not the liquid itself which actually burns
State: As the liquid evaporates, vapours are given off which mix with the oxygen in the air above the liquid and the mixture may be ignited.

6. Vapour 5.2 Colourless Heavier than air Fire Asphyxiation
5.2.6 Vapours are usually colourless and heavier than air increasing the risk of, Asphyxiation and/or Fire
FLAMMABLE VAPOUR DANGERS
State: That, since most flammable vapours are heavier than air, accumulation of the vapours in confined or enclosed spaces can lead to displacement of air with consequent suffocation dangers.
Describe: The general properties of flammable vapours.
They are colourless and thus vapour leaks from containers cannot normally be detected by observation.
Most have a perceptible odour (noticeable smell). Smells provide warnings of leaks and spillages – and hence potential dangers.
They are heavier than air (in many cases considerably heavier). Thus leaks and spillages can result in vapours flowing along the ground – possibly for long distances – and into low lying places such as drains, ditches, culverts, cellars, basements, underpasses etc. – thereby creating a fire or explosion risk in those places.
Remind: Drivers that the regulations require everyone involved in the carriage of dangerous substances to take all necessary precautions for preventing fire and explosion.

7. Other Dangers 5.2 Toxic Corrosive
5.2.7 Other possible dangers including toxicity, corrosivity and asphyxiation
Subsidiary Hazards – General
Explain: That some flammable liquids have subsidiary hazards of toxicity or corrosivity.
Provide: Some examples of flammable liquids having subsidiary hazards, select from:
Allyl chloride )
Carbon disulphide ) Flammable liquids
Ethylene dichloride ) which are also
Methanol ) toxic
Pyridine )
Acetyl chloride ) Flammable liquids
Allyl iodide ) which are also
Tripropylamine ) corrosive
State: That some flammable liquids produce acidic or toxic gases when they burn, e.g. when chlorobenzene burns hydrogen chloride gas is produced.
Contact With Skin or Eyes.
State: That some of the liquids which are toxic are also skin-absorptive and can produce poisonous effects by entering the body through the skin.
Explain: That even where the liquids are non-toxic their solvent action can dissolve the natural oils and fats in the skin, and thereby reduce the barrier property of the skin towards germs, bacteria, etc. Dermatitis and skin allergies may also develop from skin contact.
State: That many vapours from flammable liquids give rise to skin irritation and other skin problems.
Explain: That eyes can be irritated or damaged by many of the liquids or their vapours.
List: Some examples of Class 3 substances which can produce damage in the above ways, for example:
Pyridine: The liquid causes severe damage to eyes.
Irritant effect on the eyes, skin and air passages.
Vapour poisons by inhalation.
Butenone: Poisons by absorption through the skin and by inhalation.
Contact with liquid causes severe damage to eyes, and skin burns.
The vapour has an irritant effect on eyes and skin.
Furfurylamine:The liquid causes severe damage to eyes.
Toluene: Poisons by absorption through skin and inhalation.
Inhalation Of Vapour Or Liquid Droplets
State: That, if toxic, symptoms of poisoning may result.
Explain: That, even if not toxic, narcosis or irritation/damage to internal organs (e.g. respiratory tract, lungs) may be caused. (See some of the examples given above).

8. Segregation 5.2 Segregate from class 5 substances 5.2.8 Segregation
Explain: The importance of segregating flammable liquids from certain other substances, e.g. if carried on the same vehicle, oxidising agents and organic peroxides (both are oxygen providers) should be adequately segregated from flammable liquids.

9. Fire 5.2 Flashpoint Auto-ignition Flammability limits
Vapour volume ratio
5.2.9 Flashpoint, auto-ignition temperature, flammability limits (explosives limit) and liquid to vapour volume ratios
FLASH POINT
State: That the ease with which a flammable liquid will catch fire is referred to as its flammability.
Explain: That the most widely used measure of the flammability of a liquid is its Flash Point.
Define: Flash point as the lowest temperature at which a liquid gives off sufficient vapour to form a mixture with air that can be ignited by a flame or spark.
Emphasise: The following facts relating to flash point:
Vapour from a liquid below its flash point temperature is insufficient to ignite.
Vapour from a liquid at or above its flash point can be ignited. If a flammable liquid is at its flash point then the vapour air mixture will “flash” when ignited, it will not continue to burn hence the term “Flash point”.
A low flash point indicates a high flammability (the lower the flash point the higher the flammability).
State: That in the various regulations relating to the transport of dangerous substances, flash point is the principal criterion used in deciding whether liquid should be classified as a flammable liquid.
Explain: That in the regulations, a liquid having a flash point of 60º C or below would normally be classified as a flammable liquid. By derogation, diesel fuel/heating oil, light/gas oil, having a flash point above 60oC and not more than 100oC are also Class 3 substances (UN1202).
The corresponding flash point temperature for IMDG is 60ºC
State: That liquids having flash points below 23ºC are commonly described as ‘highly flammable’ on data sheets, labels etc. Similarly the description ‘extremely flammable’ is often applied to liquids with a flash point below 0ºC.
Illustrate: The wide range of flash point temperatures by listing suitable values. Some approximate flash point data are given below.
Petrol -40ºC
Kerosene +40ºC
Diesel/Gas oil +65ºC
Carbon disulphide -30ºC
Acetone -18ºC
Benzene -11ºC
Methanol +10ºC
Ethanol +12ºC
AUTO IGNITION TEMPERATURE
Define: Auto ignition temperature as the lowest temperature at which a vapour/air mixture that will ignite spontaneously without the aid of an external source of ignition such as a flame or spark.
Explain: That the heat source providing the necessary temperature could be radiated heat, a hot surface, a release of a hot vapour into the atmosphere or (as in the diesel engine) the heat produced by compression.
List: Some approximate values for auto ignition temperatures, for example:
Petrol 300ºC
Kerosene 225ºC
Diesel/Gas oil 250ºC
Carbon disulphide 100ºC
Acetone 540ºC
Benzene 540ºC
Methanol 465ºC
Ethanol 425ºC
Emphasise: That the auto ignition temperature of a substance is always much higher (often hundreds of degrees higher) than its flash point temperature. That there is no relationship between Flash Point and Auto Ignition Temperature. Use diesel as an example
Stress: That the lower the auto ignition temperature of a substance the greater the danger of fire being caused by the substance coming into contact with a hot surface such as a vehicle exhaust system.
Draw Attention:
To the unusually low value for carbon disulphide (100ºC) and point out that even the relatively low surface temperature of unlagged steam pipes would be sufficiently high to cause ignition of carbon disulphide vapour, also to the fact that it has a low Flash Point and will produce huge volumes of vapour at low temperatures.
EXPLOSIVE RANGE
Define: Explosive range (alternatively called flammable range) as the range of product vapour/air compositions, which can be ignited by a flame, spark or other hot ignition source.
State: That the lower end of the range is called the Lower Explosive Limit [LEL] and that the upper end of the range is called the Upper Explosive Limit [UEL].
LELs and UELs are normally expressed as percentage of vapour in the vapour/air mixture.
List: Some approximate values for explosive limits, for example:
%Vapour in vapour/air mixture
LEL UEL
  Petrol
Kerosene
Diesel/Gas oil
Carbon disulphide
Acetone
Benzene
Methanol
Ethanol
Ensure: That the explosive range and explosive limits are fully understood by discussing petrol as an example.
State: That the lower and upper explosive limits for petrol are 1% and 6% respectively. This means that a mixture of petrol vapour and air can be ignited (or exploded) if the percentage of petrol vapour in the mixture is between 1% and 6%, mixtures containing less than 1% or more than 6% petrol vapour will not ignite. (A car engine will not run if the petrol vapour/air mix from the carburettor is either too lean or weak [below 1% petrol] or too rich [above 6% petrol]).
Emphasise: That a normally empty receptacle or tank containing flammable vapour/air mixture within the explosive range represents a high explosion risk. Entry of a spark, flame or other high temperature source will cause an explosion.
VOLUME RATIOS
Explain: That when a liquid turns to vapour the volume of vapour produced is many times greater than the volume of the liquid.
State: That for most flammable liquids the change from liquid to vapour produces a 200 to 400 fold increase in volume. Taking a typical figure of 2% for the lower flammability limit, this means that, on evaporation, 1 litre of a flammable could produce between 10,000 and 20,000 litres of flammable (and potentially explosive) vapour/air mixture.
Relate: The above calculation to the explosive dangers of nominally empty receptacles and tanks. (The evaporation of only 3 litres of flammable liquid dregs in a 30,000 litre capacity tank would be sufficient to fill the tank with a potentially explosive vapour/air mixture, the same situation in a 45 gallon [210 litre] drum would result from the evaporation of about an egg-cup full of a flammable liquid.

10. Fire Triangle 5.2 Vapours Oxygen Sources of ignition
Combination of vapour, air and ignition source can create fire hazard
NEED TO CONTAIN VAPOURS
Explain: That since air (the normal oxygen provider) is virtually always present, fire and explosion prevention is dependent on ensuring that:
Flammable liquids and the vapours which stem from them, are not allowed to escape from containment, and, all sources of ignition are eliminated.

11. Miscible 5.2 Miscible with water – will mix
Immiscible with water – will not mix
Miscibility and Immiscibility
MISCIBILITY
State: That most flammable liquids are lighter than water.
Ensure: That drivers understand the meanings of the terms ‘miscible’ (mixable) and immiscible (not mixable).
State: That some flammable liquids are miscible with water whilst others are immiscible with water, and provide examples of liquids in each category, e.g.:
Methanol )
Ethanol ) Miscible with water
Acetone )
Petrol )
Kerosene )
Diesel/Gas Oil ) Immiscible with water
Benzene )
Toluene )
Explain: That miscibility with water is a property which needs to be taken into consideration by the emergency services when dealing with a liquid spillage or fire. In this connection bring out the following points:
Spillages of liquids, which are miscible with water, can be diluted with water (although large dilutions are often necessary before the danger of ignition is removed). Liquids, which are immiscible with water, cannot be diluted with water and since the liquids are usually lighter than water (i.e. will float on water) addition of water will not remove the fire risk.
Fire involving a liquid miscible with water can be extinguished by water jets (although large amounts of water may be required). However a fire involving a liquid immiscible with water cannot normally be extinguished by water jets. Water jets will cause the fire to spread.
Vehicles must carry fire extinguishers as required by the regulations applying to the journey (UK regs, ADR, IMDG as appropriate).

12. Spillage 5.2 Eliminate ignition sources Contain
The need for containment, prevention of escape, or exposure to situations giving rise to dangers, and the action to be taken in the event of such circumstances arising
State: If a leak or spillage occurs, eliminate all sources of ignition .
Contain if safe to do so
Recall: Vapours are heavier than air and can travel great distances
Recall: The actions to be taken in the event of an escape are as described on the information in writing,
Further action can be considered as per the emergency exercise

13. Sources of Ignition 5.2 Smoking Electrical spark Static electricity
Poor vehicle maintenance
Types of ignition sources, in particular sparks, naked flames, hot surfaces, electrical equipment, smoking and static electricity
SOURCES OF IGNITION
Discuss: The common potential sources of ignition and how risks of ignition can be minimised.
Smoking (obviously this must be banned in loading and unloading areas)
Matches, lighters should not be taken into loading/unloading areas.
Portable cooking stoves should not be used in the cab.
Non-enclosed cab heaters should not be fitted to flammable liquid vehicles.
Static electricity (effective earth bonding of tankers and tank containers during loading/unloading is a must; earthing is also necessary where, after an accident, a flammable liquid has to be transferred to another tank).
Note: Earthing cables must be connected before starting loading/unloading and not disconnected until all loading/unloading operation are
complete.
Lightning (loading/unloading of tankers and tank containers should be discontinued during an electrical storm).
Overheating of tyres )Good vehicle
Binding brakes )maintenance
Overheating wheel bearings )will
Electrical short circuits )minimise
CB radios, mobile phones etc. (do not use in loading/unloading areas)
Vehicle accidents – drive carefully
Show: Static electricity audio/visual presentation

14. PPE 5.2 Goggles Gloves Respirator for toxic vapours
Appropriate Personal Protective Equipment to include respiratory protective devices for toxic vapours
PERSONAL PROTECTIVE EQUIPMENT
Recap: The main points of protective clothing covered in the core module notes, emphasising particularly:
Tanker/tank container driver tends to be exposed to higher risks and therefore often need a higher level of protection than packaged goods drivers.
Goggles and PVC gloves should be regarded as minimum protection.
Explain: additionally a suitable respirator may be required for flammable liquids that also have a secondary hazard of being toxic or give of toxic vapours.
Show: Audio/visual presentation showing the hazardous properties of flammable liquids and vapours.