A23: Dangerous Substances And Explosive Atmospheres Regulations 2002

Dangerous substance (DS) means:

one which is explosive, oxidising, extremely flammable, highly flammable or flammable, (according to the approved classification and labelling guide whether or not it is classified under CHIP)
any other substance which creates a risk because of its physicochemical or chemical properties and its use or presence at work
any dust, which can form an explosive mixture with air, or an explosive atmosphere.

Explosive atmosphere means

a mixture, under atmospheric conditions, of air and one or more DS whether in the form of gases, vapours, mists or dusts, in which after ignition has occurred, combustion spreads to their entire unburned mixture.

Risk assessment (r5)

The employer shall make a suitable and sufficient assessment of the risk of any DS present or likely to be present in the workplace.

The assessment shall consider:

the hazardous properties of the substance
safety information provided by the supplier, including safety data sheets
the circumstances of the work, including
- the work processes and substances used and their possible interactions
- the amount of the substance involved
- the risk presented by any combination of substances
arrangements for the safe handling, storage and transport of DS and related waste
potentially high risk activities, such as maintenance
the control measures
the likelihood that an explosive atmosphere will occur and its persistence
the likelihood that ignition sources, including electrostatic discharges will be present and become active and effective
the scale of the anticipated effects of a fire or an explosion
any places which are or can be connected via openings to places in which explosive atmospheres may occur;
any additional relevant information.

This risk assessment shall be regularly reviewed to keep it up to date and particularly if:

there is a reason to suspect it is no longer valid
there has been a significant change for instance to the workplace, work processes, or organisation of the work and changes made where the review shows them to be required.

The employer (with five or more employees) shall record the significant findings of the risk assessment as soon as practicable including:

the control measures to be taken
sufficient information to show that the workplace and work processes are safely designed, operated and maintained ensuring the safe use of work equipment (see PUWER A12)
where an explosive atmosphere may occur (subject to transitional provisions r17) sufficient information to show:
- those places which have been classified into zones (r7)
- the equipment which is required for, or helps to ensure, the safe operation of equipment in hazardous locations (r7)
- that any verification by a competent person has been carried out (r7)
- the aim of any co-ordination and related measures and procedures (r11)

The employer shall, before any new work activity starts:

make an assessment, and
implement the required measures.

Elimination or reduction of risks (r6)

Every employer shall ensure that risk from DS is either eliminated or reduced as far as is reasonably practicable. This may be by, in order of priority, first substituting the DS with a substance or process which either eliminates or reduces the risk. Second by applying appropriate measures consistent with the risk assessment to:

control risks, and
to mitigate the detrimental effects of a fire or explosion or the other harmful physical effects arising from DS.

These measures, to control risks shall include, in order of priority:

reducing the quantity of DS to a minimum
avoiding or minimising the release of DS
controlling the release of DS at source
preventing the formation of an explosive atmosphere, including appropriate ventilation
ensure that any release of DS which may give rise to risk is suitably collected, safely contained, removed to a safe place, or otherwise rendered safe
avoiding ignition sources including electrostatic discharges and adverse conditions which could give rise to harmful physical effects
segregating incompatible DS

The measures to mitigate detrimental effects shall include:

reducing to a minimum the number of employees exposed
avoiding the propagation of fires or explosions
providing explosion pressure relief arrangements
providing explosion suppression equipment
providing plant constructed to withstand the pressure likely to be produced by an explosion
providing suitable PPE.

The employer shall arrange for the safe handling, storage and transport of DS, and waste containing DS, and maintain controls for the elimination or reduction of risk.

The employer should take the general safety measures listed in Schedule 1, provided they are consistent with the risk assessment and appropriate to the nature of the activity or operation.

Explosive atmospheres (r7)

Every employer shall:

classify the places where an explosive atmosphere may occur into hazardous or non-hazardous places (according to Schedule 2) and, where ‘hazardous’, into the appropriate zones
ensure that equipment and protective systems in ‘hazardous’ places complies with Schedule 3 and the relevant regulations*
mark ‘hazardous’ places with signs at their entrance(s) where necessary (according to Schedule 4)
ensure before a ‘hazardous’ place is used that the overall explosion safety is verified by a competent person (one who is competent in explosion protection as a result of experience or professional training or both)
provide appropriate work clothing which does not give rise to electrostatic discharges for use in ‘hazardous’ places.

* The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 (see Schedule 3).

Transitional Provisions apply - see below (r17)

Accidents, incidents & emergencies (r8)

In order to protect employees’ safety from an accident, incident or emergency related to DS the employer shall ensure that:

procedures, including appropriate first aid facilities and safety drills (to be tested at regular intervals), have been prepared which can be put into effect when such an event occurs
information on emergency arrangements is available, including
- details of relevant work hazards and hazard identification arrangements, and
- specific hazards likely to arise at the time of an accident, incident or emergency, and
suitable warning and other communication systems are established to enable an appropriate response, including remedial actions and rescue operations, to be made immediately when such an event occurs
where necessary, before any explosion conditions are reached, visual or audible, warnings are given and employees withdrawn, and
where the risk assessment indicates it is necessary, escape facilities are provided and maintained to ensure that, in the event of danger employees can leave promptly and safely.

The information on the procedures and systems shall be made available to relevant accident and emergency services to enable them to prepare their own response, and also if appropriate, be displayed at the workplace.

This regulation does not apply where the risk assessment shows that because of the quantity there is only a slight risk and that the control measures are sufficient.

In the event of an accident, incident or emergency related to the presence of DS at the workplace the employer shall ensure that:

immediate steps are taken to:

mitigate the effects of the event

restore the situation to normal, and

inform those employees who may be affected; and

only those persons who are responsible for carrying out repairs and other necessary work are permitted in the affected area and they are provided with

appropriate PPE, and
any necessary specialised safety equipment and plant which shall be used until the situation is restored to normal.

Information, instruction, training (r9)

Where a DS is present at work the employer shall provide suitable and sufficient information, instruction and training on the precautions and actions to be taken by the employee to safeguard himself and others including the details of the DS, also:

the name of the DS and the risks it presents
access to any relevant safety data sheet
legal requirements which concern the hazardous properties of the substance
the significant findings of the risk assessment

and this shall take account of significant changes in the type or method of work and be provided in a manner appropriate to the risk assessment.

Containers and pipes (r10)

The employer shall ensure that the contents of containers and pipes used for DS, and the nature of those contents and associated hazards, are clearly identifiable. This is subject to the requirements and exceptions in the legislation listed in Schedule 5.

Co-ordination (r11)

Where two or more employers share the same workplace (temporarily or permanently) where an explosive atmosphere may occur, the employer responsible for the workplace shall co-ordinate the requirements of these regulations to protect employees.

Transitional provisions (r17)

The requirements which relate to equipment and protective systems in (r7) and Schedule 3, do not apply to workplaces where explosive atmospheres may have occurred before 30th June 2003. However, the same workplaces shall meet the other requirements of (r7 and r11) by 30th June 2006. Workplaces in use for the first time after 30th June 2003 or modified extended of restructured after that date shall comply with (r7 and r11) from the date they are first used either to the whole premises if new, or otherwise to the extension or modification etc.

General safety measures (schedule 1)

The General Safety Measures which need to be taken to eliminate or reduce risks (r6) include:

Workplace and work processes

Ensuring that the workplace is designed, constructed and maintained so as to reduce risk.
Designing, constructing, assembling, installing, providing and using suitable work processes so as to reduce risk.
Maintaining work processes in an efficient state, in efficient working order and in good repair.
Ensuring that equipment and protective systems meet the following requirements:
- where power failure can give rise to the spread of additional risk, equipment and protective systems must be able to be maintained in a safe state of operation independently of the rest of the plant in the event of power failure
- safe means for manual override must be possible, operated by competent employees, for shutting down equipment and protective systems incorporated within automatic processes which deviate from the intended operating conditions
- on operation of emergency shutdown, accumulated energy must be dissipated as quickly and as safely as possible or isolated so that it no longer constitutes a hazard; and
- necessary measures must be taken to prevent confusion between connecting devices.

Organisational measures

The application of appropriate systems of work including:

the issuing of written instructions for the carrying out of the work; and
a system of permits to work issued by a person responsible for doing so, before the work starts
where the work is carried out in hazardous places or involves hazardous activities.

Classification of places where explosive atmospheres May occur (schedule 2)

Places where explosive atmospheres may occur

A place in which an explosive atmosphere may occur in such quantities as to require special precautions to protect the health and safety of the workers concerned is known as ‘hazardous’ by these Regulations.

Places where explosive atmospheres are not expected to occur

A place in which an explosive atmosphere is not expected to occur in such quantities as to require special precautions is known as ‘nonhazardous’ by these Regulations.

2. Classification of hazardous places

Hazardous places are classified in terms of zones on the basis of the frequency and duration of the occurrence of an explosive atmosphere.

Zone 0 : A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

Zone 1 : A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally.

Zone 2 : A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Zone 20 : A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

Zone21 : A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22 : A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Notes

1. Layers, deposits and heaps of combustible dust must be considered as any other source which can form an explosive atmosphere.

2. "Normal operation" means the situation when installations are used within their design parameters.

Criteria for the selection of equipment and Protective systems (schedule 3, see r7)

Equipment and protective systems for all places in which explosive atmospheres may occur must be selected on the basis of the requirements set out in the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 unless the risk assessment finds otherwise.

In particular, the following categories of equipment must be used in the zones indicated, provided they are suitable for gases, vapours, mists, dusts or mists and dusts, as appropriate:

in zone 0 or zone 20, category 1 equipment
in zone 1 or zone 21, category 1 or 2 equipment
in zone 2 or zone 22, category 1, 2 or 3 equipment.

Warning sign for places where explosive atmospheres may occur

Legislation concerned with the marking of Containers and pipes (schedule 5, see r10)

The Classification and Labelling of Explosives Regulations 1983 (S.I. 1983/1140)

The Chemicals (Hazard Information and Packaging for Supply) Regulations 2002 (S.I. 2002/1689)

The Health And Safety (Safety Signs And Signals) Regulations 1996(S.I. 1996/341)

The Radioactive Material (Road Transport) (Great Britain) Regulations 1996 (S.I. 1996/1350)

The Carriage of Dangerous Goods by Rail Regulations 1996 (S.I. 1996/2089)

The Packaging, Labelling and Carriage of Radioactive Material by Rail Regulations 1996 (S.I. 1996/2090)

The Carriage of Dangerous Goods (Classification, Packaging and Labelling) and Use of Transportable Pressure Receptacles Regulations 1996 (S.I. 1996/2092)

The Carriage of Explosives by Road Regulations 1996 (S.I. 1996/2093)

The Carriage of Dangerous Goods by Road Regulations 1996 (S.I. 1996/2095)

The Good Laboratory Practice Regulations 1997 (S.I. 1997/654). The Dangerous Substances And Explosive Atmospheres Regulations 2002(SI 2776)