Title: 428 413 Safety Engineering 5' Fire and Explosion Hazards and Protections 6' Toxic Substances ''
1428 413 Safety Engineering 5. Fire and
Explosion Hazards and Protections 6. Toxic
Substances ?.??.???????
???????????
????????????????????
??????????????????????????????
2References 1. D.A. Crowl, J.F. Louvar,
Chemical Process Safety Fundamentals with
Applications, Prentice Hall, 1990. 2. Dennis
P. Nolan, Handbook of Fire and Protection
Engineering Principles for Oil, Gas, Chemical,
and Related Facilities, Noyes Publication 3.
W.O.E Korver, Classifying Explosion-Prone Areas
for the Petroleum, Chemical and Related
Industries, Noyes Publication, 1995
3Fire and Explosion Hazards and Protections
4Burnt vehicles and debris left by hydrocarbon
vapor explosions that killed 15 workers at the BP
Texas City refinery March 23, 2005.
5Oct. 6, 2005 Huge flames rise from the Formosa
Plastics manufacturing complex in Point Comfort.
6Fire rages at the Marcus Oil facility on evening
of Dec. 3, 2004 following powerful tank
explosion.
7Smoke billows from heavily damaged Formosa
Plastics plant following April 23, 2004
explosion. Photo Kevin German/The State
Journal-Register.
8Introductions
- Fire, explosions and environmental pollution are
the most serious "unpredictable" life affecting
and business losses having an impact on
industries today. - Accidents
- Most accidents can be thought of as
non-preventable, all accidents are in fact
preventable.
9The main cause of accidents or failures can be
- Ignorance
- Economic Considerations
- Oversight and Negligence
- Unusual Occurrences
10Ignorance
- Incompetent design, construction or inspection
occurs. - Supervision or maintenance occurs by personnel
without the necessary understanding. - Assumption of responsibility by management
without an adequate understanding of risks. - There is a lack of precedent.
- There is a lack of sufficient preliminary
information. - Failure to employ competent Loss Prevention
professionals.
11Economic Considerations
- Initial engineering and construction costs for
safety measures appear uneconomical. - Operation and maintenance costs are unwittingly
reduced to below what is necessary.
12Oversight and Negligence
- Unethical behavior occurs.
- Professional engineers and designers commit
errors. - Contractual personnel or company supervisors
knowingly assume NO risks. - Lack of proper coordination in the review of
engineering designs. - Failure to conduct prudent safety reviews or
audits.
13Unusual Occurrences
- Natural catastrophes - earthquakes, extreme
weather, etc. - Political upheaval - terrorist activities.
- Labor unrest, vandalism.
14Fire and Explosion Protection Engineering Role
- is not a stand alone discipline,
- should be an integrated aspect of how a facility
is designed arranged and constructed. - Should be integral with all members of the design
team, be it structural, civil, electrical,
process, etc. Risk engineer should mainly be in
an advisory role. - In addition Risk Engineer must have expertise in
hazard, safety, risk and fire protection
principles and practices applied to the petroleum
or other related industries.
15Risk Management and Insurance
- The four methods, in order of preference are
- Risk Avoidance
- Risk Reduction
- Risk Insurance
- Risk Acceptance
16- Senior management responsibility and
accountability are the keys to providing
effective fire and explosion safety measures at
any facility or operation.
17Fire Dynamics
- Combustion reaction the structure of the flame
or reaction zone. - 2 types of reactions
- Premixed flame reaction oxidizer and fuel are
mixed prior to their entry to the combustion
zone. - Diffusion flame reactions oxidizer and fuel are
mixed in the vicinity of the flame.
18Reactions
- Oxidation reaction is the chemical combination of
oxygen with any substance. - The substance is oxidized.
- Rust is an example of oxidized iron. In this
case, the chemical reaction is very slow. - The very rapid oxidation of a substance is called
combustion, or fire with simultaneous evolution
of radiation energy, usually heat and light.
19Combustions
- Combustion theories
- the fire triangle,
- the tetrahedron of fire, and
- the life cycle of fire.
20The Fire Triangle
- There are three things necessary to have a fire
fuel, oxygen (or an oxidizer), and heat (or
energy).
21Fuel
- Anything that will burn.
- Fuels may be categorized into the following
classes - 1. Elements (which include the metals,
and some non-metals such as carbon, sulphur, and
phosphorus) - 2. Hydrocarbons
- 3. Carbohydrates (including mixtures that
are made up partially of cellulose, like wood and
paper) - 4. Many covalently bonded gases
(including carbon monoxide, ammonia, and hydrogen
cyanide) - 5. All other organic compounds.
22Hydrocarbon
- Hydrocarbon must first be in a vapor condition
before combustion processes can occur. - Liquids however must have significant vapor
emissions in order for flammable concentrations
to be present for combustion processes to occur. - Gases by their nature are immediately ignitable
and can produce a fast burning flame front that
generates into an explosive force in confined
areas.
23Oxidizer
- Oxygen is the most common oxidizing agent
- Most firefighters consider only oxygen, since the
greatest source of oxygen is the atmosphere.
24Energy
- All forms capable of providing the source of
energy needed to start the combustion process. - The energy can be generated chemically by the
combustion of some other fuel, or it can be
generated by some other exothermic chemical
reaction. - Energy may also be generated by mechanical
action - Static electricity is created whenever molecules
move over and past other molecules. - A third method of generation of energy is
electrical. This method may manifest itself as
heat, as produced in an electrical heater, as
arcing in an electrical motor or in a "short"
circuit, or as the tremendous amount of energy
released as lightning. - The fourth method of generation of energy is
nuclear.
25Energy
- Once the energy - in many cases, heat - is
generated, it must be transmitted to the fuel
(the "touching" of the fuel and energy legs). - This process is accomplished in three ways
- Conduction the transfer of heat through a
medium, such as a pan on a stove's heating
element), - Convection the transfer of heat with a medium,
such as the heated air in a hot-air furnace), and - Radiation the transfer of heat which is not
dependent on any medium.
26Oxidation
- A law of nature, that when fuel, oxidizers, and
energy are brought together in the proper
amounts, a fire will occur. - If the three are brought together slowly, and
over a long period of time, the oxidation will
occur slowly, as in the rusting of iron. - If the three are of a particular combination, the
resulting oxidation reaction might even be an
explosion. - Whatever form the final release of energy takes,
the thing that cannot be changed is that the
chemical reaction will occur.
27The Tetrahedron Theory
Diffusional continuous re-ignition
automatically obtained at flame temperature
levels. Fuel is in form of vapor and/or gas.
28The Tetrahedron Theory
- This theory encompasses the three concepts in the
fire triangle theory but adds a fourth "side" to
the triangle, making it a pyramid, or
tetrahedron. - The fourth side is called the "chain reaction of
burning".
29The Life Cycle Theory
- The input heat, which is defined as the amount of
heat required to produce the evolution of vapors
from the solid or liquid. The input heat will
also be the ignition source and must be high
enough to reach the ignition temperature of the
fuel - The fuel part the fuel must be in the proper
form to bum - The fourth part of the theory is proportioning,
or the occurrence of intermolecular collisions
between oxygen and the hydrocarbon molecule (the
"touching" together of the oxidizer leg and the
fuel leg of the fire triangle).
30The Life Cycle Theory
- The fifth step is mixing that is, the ratio of
fuel to oxygen must be right before ignition can
occur (flammable range). - The sixth step is ignition continuity, which is
provided by the heat being radiated from the
flame back to the surface of the fuel
31The Life Cycle Theory
32Products of Combustion
- Heat and combustible gases (inviscible) e.g.
- Carbon dioxide CO2
- Carbon monoxide CO
- Sulfur dioxide SO2
- Acrolein CH2CHCHO
- Hydrochloric acid HCl
- Hydrofluoric acid HF
- Hydrogen cyanide HCN
- Oxides of Nitrogen NOx
- Flame and smoke
33Heat Released From Combustion
- Depend on the type of fuel, a specific amount of
heat is released which called heat of combustion.
- In ideal combustion of 0.45 kg (1 lb) of methane,
approximately 25,157 kJ (23,850 Btu) are
released. - The temperature of the combustion products is
normally taken to be 1200 oC, which is a typical
hydrocarbon fire temperature.
34Heat Released From Combustion
- Heat flux is considered the more appropriate
measure by which to examine the radiation effects
from a fire. - A radiant heat flux of 4.7 kW/m2 will cause pain
on exposed skin, a flux density of 12.6 kW/m2 or
more may cause secondary fires and, - A flux density of 37.8 kW/m2 will cause major
damage to a process plant and storage tanks.
35Fires
- Jet Fire
- Most fires involving gas will be associated with
a high pressure and labeled as "jet" fires. - A jet fire is a pressurized stream of combustible
gas or atomized liquid that is burning. If such a
release is ignited soon after it occurs, (i.e.,
within 2 -3 minutes), the result is an intense
jet flame. - This jet fire stabilizes to a point that is close
to the source of release, until the release is
stopped. - A jet fire is usually a very localized, but very
destructive to anything close to it.
36Fires
- Pool Fire
- Once a pool of liquid is ignited, gas evaporates
rapidly from the pool as it is heated by the
radiation and convective heat of the flame. - Pool fires have some of the characteristics of a
vertical jet fire, but their convective heating
will be much less.
37Fires
- Flash Fire
- If a combustible gas release is not ignited
immediately, a vapor plume will form. This will
drift and be dispersed by the ambient winds or
natural ventilation. If the gas is ignited at
this point, but does not explode, it will result
in a flash fire, in which the entire gas cloud
burns very rapidly. - It is unlikely to cause any fatalities, but will
damage steel structures.
38Explosions
- A detonation is a shock reaction where the
flames travel at supersonic speeds (i.e., faster
than sound). - Deflagrations are where the flames are traveling
at subsonic speeds. - The explosion occur in pressurized gas and air
systems (i.e., process vessels and piping). It is
generally recognized that vapor cloud explosions
have flames that travel at subsonic speeds.
39Explosions (Detonations)
- Detonations can occur in solids and liquids but
are particularly frequent in petroleum facilities
in mixtures of hydrocarbon vapors with air or
oxygen. - Detonations will develop more rapidly at initial
pressures above ambient atmospheric pressure. If
the initial pressure is high the detonation
pressure will be more severe and destructive. - Detonations produce much higher pressures than
the ordinary explosion. In most cases a process
vessel or piping systems will be unable to
contain detonation pressure. - The only safe procedure is to avoid process
system detonations is to preventing the formation
of flammable vapor and air mixtures within
vessels and piping systems.
40Vapor Cloud Explosions
- The ignition of combustible gas or vapor
releases in the open atmosphere. - It will only occur if there is sufficient
congestion or in some cases turbulence of the
open air is occurring, - Vapor cloud explosions are high-speed, but have
subsonic combustion resulting in a deflagration
not a detonation. - Four conditions have to be achieved
- There has to a significant release of flammable
material. - The flammable material has to be sufficiently
mixed with the surrounding air. - There has to be an ignition source.
- There has to be sufficient confinement,
congestion, or turbulence in the released area.
41Smoke and Combustion
- Fatalities causes mainly from smoke and gas
inhalation. - Smoke lt 1 mm.
- The narcotic gases i.e. CO, HCN, CO2 are the main
danger and cause incapacitation by an attack on
the nervous system. - Low level of O2 in brain
- Psychological disorder i.e. impaired judgment
ands concentration, confused, panic and
incapacitate personnel.
42Smoke and Combustion
- SO2 suffocating by blocking transport of O2 in
the blood. - CO hemoglobin causes death.
- CO has an affinity 300 times that of O2.
- CO in blood 70-80 causes death.
43Smoke and Combustion
- HCN Hydrocyanic gas
- They render the O2 unavailable to the tissues,
and cause death through asphyxia. - Inhaling 180 ppm of HCN lead to unconsciousness.
Fatal effect would be caused by CO poisoning
after victim unconscious. - Hot gas Inhaling will cause tissue damage.
- Psychological the sight and causes panic and
disorientation.
44 Hazards Considerations
- Ease of ignition
- Source of ignition available
- Spill potential
- Fire exposure
- Container provided
- Flammable range
- Health exposure
45(No Transcript)
46(No Transcript)
47(No Transcript)
48Flammable and Combustible Liquid Hazards
- Definitions
- Flash point
- Fire point
- Limits of flammability
- Auto-ignition temperature
- Flammability
- Combustibility
49The MainCharacteristics of Combustible Materials
- Lower Flammable (Explosive) Limit (LFL or
LEL)/Upper Flammable Limit (UFL or UEL). - This is the range of flammability for
a mixture of vapor or gas in air at normal
conditions. - Material Range Difference
- Hydrogen 4.0 to 75.6 71.6
- Ethane 3.0 to 15.5 12.5
- Methane 5.0 to 15.0 10.0
50The MainCharacteristics of Combustible Materials
- Flash Point
- The lowest temperature of a flammable liquid at
which it gives off sufficient vapor to form an
ignitable mixture with the air near the surface
of the liquid or within the vessel used. - Material Flash Point
- Hydrogen Gas
- Butane -60 oC (-76 oF)
- Hexane -22 oC (-7 oF)
51The MainCharacteristics of Combustible Materials
- Autoignition Temperature (AIT)
- The minimum temperature at to which a substance
in air must be heated to initiate or cause self
sustaining combustion independent of the heating
source. - Material AIT
- Heptane 204 oC (399 oF)
- Hexane 225 oC (437 oF)
- Butane 287 oC (550 oF)
-
52The MainCharacteristics of Combustible Materials
- Vapor Density
- The relative density of the pure vapor or gas
when compared to air. - Vapor Pressure
- This is the property of a substance to vaporize.
- Flammable
- Combustible
- Heat of Combustion
53Purpose of the Dow Fire and Explosion Index
- To serve as a guide to the selection of fire
protection methods. - To help evaluate the overall risk from fire
explosion (FEI). - To better understand the potential risks.
54NFPA Standard and Basic Classifications of
Flammable Liquids
- Class 1 a closed-cup flashpoint below 100 oF at
a vapor pressure lt 40 psi. - Class 2 a closed-cup flashpoint at or above 100
oF but below 140 oF. - Class 3 a closed-cup flashpoint at or above 140
oF.
55NFPA Vapor Pressure vs Vapor Travelling
Distances
- Liquid Flash Pt. Liquid VP (atm)
Vapor Travelling - Class (?F) Temp (?F) Distances
- I 50 200 0.45
Large - II 100 200 0.12
Small - III 140 200 0.048
Minimal
56NFPA Molecular Weight vs Vapor Travelling
Distances
- Liquid Flash Pt. Liquid VP (atm) MW
Vapor Travelling - Class (?F) Temp (?F)
Distances - I 50 200 0.45
Minimal Large - II 100 200 0.45
Small Small - III 140 200 0.45
Large Minimal
57Dust Explosion
- An explosion results when the dust cloud has a
concentration above the LEL. - The explosion intensity depends on the rate of
pressure rise. - Dust explosion is the simplest way of eliminating
the an explosion hazard such as an automatically
operated water spraying system that keeps solid
fuel constantly wet.
58Mechanism of Fire Extinguishment
- Four majors requirements for a combustion
reaction - Sufficient oxidizer
- Fuel vapor
- Heat input (ignition source)
- Continuous chain reaction
- These 4 elements also become the mechanisms for
extinguishing a fire.
59Extinguishment by Cooling
- Water is the most effective means of removing
heat from ordinary combustible materials such as
wood, paper, cardboard, - Reducing and ultimately stopping the rate of
release of combustible vapors and gases.
60Extinguishment by Oxygen Dilution
- The term dilution can only be applied to the
gaseous state. - The necessary degree of O2 dilution varies
greatly with the particular fuel. - The O2 requirements for flaming is 16 and
smoldering is 5. - Carbon dioxide is used in the total flooding of
closed or semi-closed spaces.
61Extinguishment by Fuel Removal
- Removing the fuel or indirectly shutting off the
fuel vapors to combustion in the flaming mode by
simply covering the fuel. - The use of surfactant foams is a typical example.
- The cooling of a fuel surface essentially results
in the removal of fuel vapor.
62Extinguishment by Chemical Flame Inhibition
- Can be applied in the flaming mode only.
- This method is partially understood and is the
subject of major continuing research. - This method is the extreme rapidity and the high
relative efficiency with which flames can be
extinguished.
63Extinguishment by Chemical Flame Inhibition
(contd.)
- Combustion is a chain reaction process. Active H
interact with O2 molecule to produce active OH
and O species. - These active species are formed as products as
well as consumed as reactants and can be called
chain carriers. - Extinguishment by flame inhibitors is possible
only when the active species are not allowed to
fulfill their role in sustaining the flame.
64Extinguishment by Chemical Flame Inhibition
(contd.)
- Inhibitors
- Gaseous and liquid halogenated hydrocarbons
wherein the effectiveness increase as higher
order halogens are used. - Bromotrifluoromethane CBrF3 Halon 1301
- Bromochlorodifluoromethane CBrClF2 Halon 1211
- Dibromotetrafluoroethane CBrF2CBrF2 Halon 2402
65Extinguishment by Chemical Flame Inhibition
(contd.)
- Inhibitors
- Alkali metals, salts wherein the cationic portion
is Na, K, and the anionic portion is either
bicarbornate, carbamate, or halide. - Sodium bicarbornate regular dry chemical
- Potassium bicarbornate purple X
- Potassium carbarmate Monnex
- Potassium chloride Super K
66Extinguishment by Chemical Flame Inhibition
(contd.)
- Inhibitors
- Ammonium salts, the most prominent of which is
mono-ammonium phosphate wherein the cationic
ammonium radical (NH4) and the ionic phosphate
radical (H2PO4) are formed with the latter
absorbing an H active radical.
67Design Objectives in the Chemical Plants
- A major emphasis of all systems in plants is
defense in depth. - Fire safety requires fire prevention and fire
protection to be implemented by both engineering
design and administrative control.
68Fire Prevention by Design
- Can be achieved by removing fuel, removing
ignition sources, or removing oxidizing agents
(air). - 3 controls
- Control of fuel,
- Control of ignition sources, and
- Control of oxidizing agent.
69Fire Prevention by Design
- Combustible Materials
- It should be clear that control of combustibles
should be a primary design criteria for plants.
This control can be engineered by - Locating necessary combustible remote from the
potential ignition sources, - containing combustibles in suitable enclosures
to prevent exposure to ignition sources, and - selecting non-combustibles as substitutes for
combustibles. - Location, containment, material
selection/substitution.
70Fire Prevention by Design
- Typical design practices to prevent vapor cloud
explosions - All hydrocarbon areas should be provided with
maximum ventilation capability. - Enclosed spaces are avoided.
- Installation of walls and roofs are used only
where necessary (including firewalls). - Generally hydrocarbon floors areas are open
grated construction when elevated, unless solid
floors are provided where there is a need for
spill protection or a fire or explosion barrier,
otherwise ventillation requirements will prevail.
71Fire Prevention by Design
- Area congestion should be kept to a minimum.
- Vessels should be orientated to allow maximum
ventilation or explosion venting. - Bulky equipment should not block air circulation
or dispersion capacity. - Release or exposure of flammable vapors to the
atmosphere should be avoided. - Waste HC gases should be routed to the flare or
return to the process. - Sampling techniques should use a closed system.
- Process equipment liquid drains should use a
sealed drainage system. - Open drain ports should be avoided and separate
sewage and an oily water drain systems should be
provided. - Surface drainage should be provided to remove
spills immediately and effective from the process
area.
72Fire Prevention by Design
- Gas detection is provided, particularly to areas
handling low flash point materials with a
negative or neutral buoyancy. - Air or oxygen is eliminated from the interior of
process system i.e. vessels, piping and tanks. - Protective devices are located outside hazardous
areas or behind protective barriers. - Semi or permanently occupied buildings required
in or adjacent process areas are constructed to
withstand expected explosion overpressure.
73Fire Prevention by Design Vapor
- Dispersion enhancements water sprays.
- Large updraft air cooler fans.
- Location optimization based on prevailing winds.
- Supplemental ventilation systems.
- Damage limiting construction.
- Pre-installed or engineered features into the
design of the facility or equipment. - Fireproofing.
74Fire Prevention by Design
- Building Materials
- Interior finishes
- Thermal insulator
- Structural materials
- Process and Equipment Materials
- Cable insulation
- Lubrication fluids
- Cooling and insulating fluids
- Solvents
- Ion exchange
75Fire Prevention by Design
- Ignition Sources
- Potential sources of heat energy
- Electrical Energy can be converted to heat of
ignition in a variety of ways. - The flow of current through a material produces
heat by either resistance or inductance. - Making or breaking of an electrical circuit such
as a short circuit or a switch can cause arcing. - Frequently these two forms work together for
example, resistance heating can cause a softening
of wire insulation and lead to a short circuit
and fire.
76Fire Prevention by Design
- Potential sources of heat energy (contd.)
- Static electricity is generated by the contact
and separation of materials (sometimes referred
to as frictional electricity). Energy can be
converted to heat of ignition in a variety of
ways. - Machines belts or the flow of flammable liquids.
- Lightning.
- Heated equipment
- Hot piping e.g. steam lines,
- Space heaters,
- Open flame.
77Fire Prevention by Design
- Potential sources of heat energy (contd.)
- Mechanical Heat Energy
- Frictions Heat, sparks
- Heat of compression
- Chemical Heat Energy
- Spontaneous heating
- Heat of decomposition
- Heat of solution
- Heat of reaction
- Human
78Fire Prevention by Design
- Oxidizing agents
- The most case is O2.
- This is accomplished by inerting process
equipment, tanks, or rooms where applicable.
79Fire Protection by Design
- Focuses on managing the impact of a fire.
- The most case is O2.
- It is unlikely that all fire can be prevented.
- The objectives are
- Control of fire with building design,
- Control of fire with fire protection systems and
equipment.
80Fire Protection by Design
- Control of fire with building design.
- It is a very effective way to manage the impact
of fire. - Passive protection building design encompass
plant layout to separate hazards from important
areas, compartment to limit the spread of fire,
and various fire barriers or fire retardants to
reduce the growth or spread of fire.
81Fire Protection by Design
- Control of fire with fire protection systems and
equipment. - Active protection to detect and suppress fire
before un-acceptable damage has occurred.
82Administrative Control of Fire Hazards
- Fire safety requires
- Active protection to detect and suppress fire
before un-acceptable damage has occurred. - Purpose of administrative control
- Training
- Fire prevention
- Maintain effective program
83Method of Administrative Control
- Procedural
- Operating,
- Maintenance,
- Procurement, and
- Design/construction
- Permit systems
- Hazardous work permit
- Control of materials
- Technical specifications
84Enforcement of Administrative Control
- Coordination (authority and responsibility)
- Training
- Inspection
- Audits
85Maintaining Program Integrity
- Design review
- Contractor supervision
- Authority for enforcement
- Inspection/test of fire protection equipments
- Control of fire protection system impairments
- Outage approval
- Records to assure reinstatement
- Additional safeguard
86 Hazard Control
- Eliminate or replace liquid
- Confine vapors maintaining the vapor outside of
the flammable range - Control of ignition sources
- Control environment (air or temperature)
- Containers and fire barriers
- Fire suppression
87 Employers and the self-employed must
- Carry out a risk assessment of any work
activities involving dangerous substances - Provide technical and organizational measures to
eliminate or reduce as far as is reasonably
practicable the identified risks - Provide equipment and procedures to deal with
accident and emergencies - Provide information and training to employees
- Classify places where explosive atmospheres may
occur into zones, and mark the zones where
necessary.
88 Industries affected
- Storage of petrol.
- Use of flammable gases, such as acetylene, for
welding - Handling and storage of waste dusts in a range of
manufacturing industries - Handling and storage of flammable wastes
including fuel oils - Hot work on tanks or drums that have contained
flammable material - Work activities that could release naturally
occurring methane - Dusts produced in the mining of coal
- Use of flammable solvents in pathology and school
laboratories - Storage/display of flammable goods, such as
paints, in the retail sector - Filling, storage and handling of aerosols with
flammable propellants, such as LPG - Transport of flammable liquids in containers
around the workplace - Deliveries from road tankers, such as petrol or
bulk powders - Chemical manufacture, processing and warehousing
- Petrochemical industry - onshore and offshore
89 Industries affected
- Fired heaters
- Pumps handling hydrocarbon materials
- Reactors
- Compressors
- Large hydrocarbon inventory vessels, columns, and
drums
90 Safety Measures
- To ensure that the safety risks from dangerous
substances are either eliminated or reduced to as
far as is reasonably practicable. - Where it is not reasonably practicable to
eliminate risks, employers are required to take,
so far as is reasonably practicable, measures to
control risks and measures to mitigate the
detrimental effects of a fire or explosion or
similar event.
91 Safety Measures
- Elimination is the best solution and involves
replacing a dangerous substance with a substance
or process that totally eliminates the risk. In
practice this is difficult to achieve and it is
more likely that it will be possible to replace
the dangerous substance with one that is less
hazardous (e.g. by replacing a low flashpoint
solvent with a high flashpoint one) or to design
the process so that it is less dangerous for
example, by reducing quantities of substances in
the process, this is known as process
intensification. - However care must be taken whilst carrying out
these steps so as to ensure that no other new
safety or health risks are created or increased.
92 Control Measures
- Reduce the quantity of dangerous substances to a
minimum - Avoid or minimize releases
- Control releases at source
- Prevent the formation of an explosive atmosphere
- Collect, contain and remove any releases to a
safe place (e.g. by ventilation) - Avoid ignition sources
- Avoid adverse conditions (e.g. exceeding the
limits of temperature or control settings) that
could lead to danger - Keep incompatible substances apart
93 Mitigation
- Reducing the numbers of employees exposed
- Providing plant which is explosion resistant
- Providing explosion suppression or explosion
relief equipment - Taking measures to control or minimise the spread
of fires or explosions - Providing suitable Personal Protective Equipment
(PPE)
94 Reduction of Risks
- Design, construction and maintenance of the
workplace (e.g. fire-resistance, explosion
relief) - Design, assembly, construction, installation,
provision, use and maintenance of suitable work
processes, including all relevant plant,
equipment, control and protection systems - The application of appropriate systems of work
including written instructions, permits to work
and other procedural systems of organising work
95 Places where Explosive Atmospheres can occur
- areas where hazardous explosive atmospheres may
occur are classified into zones based on their
likelihood and persistence - areas classified into zones are protected from
sources of ignition by selecting equipment and
protective systems meeting the requirements of
the Equipment and Protective Systems Intended for
Use in Potentially Explosive Atmospheres
Regulations
96 Places where Explosive Atmospheres can occur
- where necessary, areas classified into zones are
marked with a specified "EX" sign at their points
of entry - where employees work in zones areas they are
provided with appropriate clothing that does not
create a risk of an electrostatic discharge
igniting the explosive atmosphere - before coming into operation for the first time,
areas where explosive atmospheres may be present
are confirmed as being safe (verified) by a
person (or organisation) competent in the field
of explosion protection. The person carrying out
the verification must be competent to consider
the particular risks at the workplace and the
adequacy of control and other measures put in
place.
97 Arrangements to deal with accidents, incidents
and emergencies
- Suitable warning (including visual and audible
alarms) and communication systems - Escape facilities if required by the risk
assessment - Emergency procedures to be followed in the event
of an emergency - Equipment and clothing for essential personnel
dealing with the incident - Practice drills
- Making information on the emergency procedures
available to employees - Contacting the emergency services to advise them
that information on emergency procedures is
available (and providing them with any
information they consider necessary)
98 Information instruction and training
- Employers are required to provide employees and
other people at the workplace who might be at
risk with suitable information, instruction and
training on precautions and actions they need to
take to safeguard themselves and others,
including - Names of the substances in use and risks they
present - Access to any relevant safety data sheet
- Details of legislation that applies to the
hazardous properties of those substances - The significant findings of the risk assessment
- The significant findings of the risk assessment.
99Determination of the presence of dangerous
substances
- You will need to carry out the following two
steps - - Check whether the substances have been classified
under the Chemicals (Hazard Information and
Packaging for Supply) Regulations as explosive,
oxidising, extremely flammable, highly flammable
or flammable - Assess the physical and chemical properties of
the substance or preparation and the
circumstances of the work involving those
substances to see if that can create a safety
risk to persons from an energetic event.