Controlling pressure - Drown out, quenching or dumping
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- Considered as special cases of crash cooling
- Objective is to slow down the reaction my mixing a large quantity or cold
liquid
- Provides either a sufficient heat sink to remove the heat of the reaction or
reduces rate of reaction by lowering the temp, or by diluting the reactants
concentrations
- If there is sufficient space you can consider introductions the quench fluid
directly into the reactor from a standby tank
, - Dump the contents of the reactor into a separate containment vessel
containing the quench water
Risk control hierarchy - machinery
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- Eliminating the risks - design should minimise risks at all phases of the life
of the equipment including construction, transport, installation,
commissioning, decommissioning, disposal, recycling
- Hardware (Physical) - guards, protection devices, isolation/ lock off,
equipment controls, ensure operating conditions are regulated, protection
against specified hazards
- Software (Procedural/ behavioural) - information, instruction, training,
supervision, safe systems of work, warning signs, maintenance instructions,
specific risks use restriction with adequate training
- PPE is rarely an option when dealing with pure machinery risks
Current
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- Flow of electrons through conductors
- Flows due to differences in electrical pressure between two points or
potential difference, it is measured in Volts
- DC current flows continuously in the same direction
- AC constantly reverses its direction of flow
- UK reverses at 50 times every second or 50 Herts (Hz)
Flammable liquids - temperature definitions
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- Flash point: the lowest temp at which a liquid produces sufficient vapour
to ignite on the application of a small pilot flame. When the pilot flame is
applied all the vapours are consumed. This is faster than the vapours being
consumed. When the pilot flame is removed the flame will go out.
- Fire point: the lowest temp at which a liquid produces sufficient vapours
to produce sustained combustion on the application of a pilot flame.
Usually about 5 to 8 degrees above the flash point. Vapours ignite but are
now being produced faster than the fire Is consuming them. Take the pilot
flame away and it will continue to burn
- Ignition temperature: the temperature to which a material has to be
heated for sustained combustion to be initiated from a pilot source
- Auto ignition temperature: The temp at which the vapour being given off
will ignite spontaneously without an outside ignition source.
Classification of hazardous areas, zoning - dusts
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- Zone 20 - explosive atmosphere present continuously or for long periods
of time
- Zone 21 - explosive atmosphere present occasionally under normal
operating circumstances
- Zone 22 - explosive atmosphere not normally present and then only for
short periods
Runaway reactions
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- Of most concern in chemical processing is exothermic reactions
- If the heat released cannot be removed effectively it presents a potential
hazard by remaining in the reaction mass
, - with the consequence of raising the reaction mass temperature, and
hence reaction rate, resulting in a runway reaction
Avoiding danger from underground services
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- Particularly hazardous because they are concealed, frequently close to
the surface, sometimes occur in unexpected locations and often poorly
protected
- Damage to live cables often results in arcing currents with associated
explosive effects, fire and flames
- Usually causes severe, potentially fatal buns to the hands, face and torso
- A safe system of work incorporating the following should be used:
o Use of cable location plans, frequently inaccurate so cannot always e
relied upon to give accurate information
o Cable locating devices, as cables are located their routes should be
marked on the surface of the ground. Only to be used by trained operators
o Safe digging practice, trial holes should be dug to expose the cables.
Hand tools should be used. Preferable that excavations should be
alongside rather than above the cables.
o Trained personnel
Principles in loading and unloading of tankers and tank containers
Give this one a try later!
Give this one a try later!
- Considered as special cases of crash cooling
- Objective is to slow down the reaction my mixing a large quantity or cold
liquid
- Provides either a sufficient heat sink to remove the heat of the reaction or
reduces rate of reaction by lowering the temp, or by diluting the reactants
concentrations
- If there is sufficient space you can consider introductions the quench fluid
directly into the reactor from a standby tank
, - Dump the contents of the reactor into a separate containment vessel
containing the quench water
Risk control hierarchy - machinery
Give this one a try later!
- Eliminating the risks - design should minimise risks at all phases of the life
of the equipment including construction, transport, installation,
commissioning, decommissioning, disposal, recycling
- Hardware (Physical) - guards, protection devices, isolation/ lock off,
equipment controls, ensure operating conditions are regulated, protection
against specified hazards
- Software (Procedural/ behavioural) - information, instruction, training,
supervision, safe systems of work, warning signs, maintenance instructions,
specific risks use restriction with adequate training
- PPE is rarely an option when dealing with pure machinery risks
Current
Give this one a try later!
- Flow of electrons through conductors
- Flows due to differences in electrical pressure between two points or
potential difference, it is measured in Volts
- DC current flows continuously in the same direction
- AC constantly reverses its direction of flow
- UK reverses at 50 times every second or 50 Herts (Hz)
Flammable liquids - temperature definitions
,Give this one a try later!
- Flash point: the lowest temp at which a liquid produces sufficient vapour
to ignite on the application of a small pilot flame. When the pilot flame is
applied all the vapours are consumed. This is faster than the vapours being
consumed. When the pilot flame is removed the flame will go out.
- Fire point: the lowest temp at which a liquid produces sufficient vapours
to produce sustained combustion on the application of a pilot flame.
Usually about 5 to 8 degrees above the flash point. Vapours ignite but are
now being produced faster than the fire Is consuming them. Take the pilot
flame away and it will continue to burn
- Ignition temperature: the temperature to which a material has to be
heated for sustained combustion to be initiated from a pilot source
- Auto ignition temperature: The temp at which the vapour being given off
will ignite spontaneously without an outside ignition source.
Classification of hazardous areas, zoning - dusts
Give this one a try later!
- Zone 20 - explosive atmosphere present continuously or for long periods
of time
- Zone 21 - explosive atmosphere present occasionally under normal
operating circumstances
- Zone 22 - explosive atmosphere not normally present and then only for
short periods
Runaway reactions
Give this one a try later!
- Of most concern in chemical processing is exothermic reactions
- If the heat released cannot be removed effectively it presents a potential
hazard by remaining in the reaction mass
, - with the consequence of raising the reaction mass temperature, and
hence reaction rate, resulting in a runway reaction
Avoiding danger from underground services
Give this one a try later!
- Particularly hazardous because they are concealed, frequently close to
the surface, sometimes occur in unexpected locations and often poorly
protected
- Damage to live cables often results in arcing currents with associated
explosive effects, fire and flames
- Usually causes severe, potentially fatal buns to the hands, face and torso
- A safe system of work incorporating the following should be used:
o Use of cable location plans, frequently inaccurate so cannot always e
relied upon to give accurate information
o Cable locating devices, as cables are located their routes should be
marked on the surface of the ground. Only to be used by trained operators
o Safe digging practice, trial holes should be dug to expose the cables.
Hand tools should be used. Preferable that excavations should be
alongside rather than above the cables.
o Trained personnel
Principles in loading and unloading of tankers and tank containers
Give this one a try later!
