IC2 - Principles Of Fire & Explosion

Question 0

The effects of fire on concrete

Answer 0

• does not conduct heat
• will spall and disintegrate as temperatures rise
• reinforcing rods will act as conductors
• loss of strength in cooling

Question 1

The effects of fire on steel

Answer 1

• heats up and twists & buckles
• conducts heat through a structure
• regains strength once cool - however properties may have changed

Question 2

What are the effects of fire on wood

Answer 2

• smoulder and char initially - burn as temperature increases
• rate of charging depends on the density of wood joints
• generates smoke and fumes
• burns on the outside leaving the inside strong
• some varieties of timber can be more fire resistant than others

Question 3

What is meant by fire stopping

Answer 3

Fire stopping is preventing the spread of smoke and flame by placing obstructions across air passageways, ventilation ducts and gaps around doors these must have the facility to block in the event of a fire.

Question 4

Methods of explosion relief

Answer 4

• explosion venting
• bursting discs
• explosion panels
• suppression

Question 5

What are the hazardous phase zones for flammable vapours

Answer 5

Zone 0 - is present continuously or for ling periods of time or frequently

Zone 1 - is likely to occur in normal operations occasionally

Zone 2 - is not likely to occur in a normal operation, but if it does occur will persist for a short period only

Question 6

What are the hazardous phase zones for combustible dusts

Answer 6

Zone 20 - dust is present for long periods of time continuously

Zone 21 - dust is likely to occur in normal operations occasionally

zone 22 - dust is not likely to occur in a normal operation but if it does occur will persist for a short time only

Question 7

Key principles for preventing and minimising a dust explosion

Answer 7

• Elimination at source of ignition
• limit dust cloud generation
• mitigate the explosion

Question 8

What is a vapour cloud explosion

Answer 8

• confined in a tank, vessel or building
• unconfined as a release of large quantities into the air
• may rise from vaporisation of a release of a liquified gas from a ruptured vessel
• ignited by ignition source
• fire explosion and resulting debris from over pressure

Question 9

what is the hierarchy of control to minimise the probability of explosion

Answer 9

1. avoid or minimise the release - using enclosed systems + maintaince to prevent loss of contaminants
2. control release at source - detection + automatic shut off systems
3. prevent the formation of explosive atmosphere - ventilation and inert atmosphere
4. release is collected, contained & removed - bunding & emergency arrangements
5. avoid ignition sources - areas zoned / appropriate electrical equipment is used
6. prevent smoking & static clothing - PTW if necessary
7. avoid adverse conditions - protect storage vessels against weather & vehicles
8. segregation of incompatible dangerous substances

Question 10

what are the control measures for eliminating ignition sources in a high dust area

Answer 10

• correct assessment of zoning
• electrical bonding and earthing
• extraction of ferrous metal contaminants from the product using magnets
• prevention of equipment hot spots
• no smoking policy & enforcement
• non sparking tools
• electrical conducting safety footwear to prevent static generation

Question 11

how can dust cloud suppression be achieved

Answer 11

• ensuring that ducting is dust tight
• good housekeeping to prevent overfilling silo, such interlocking
• means to prevent overfilling silos such as interlocking
• LEV at point of transfer
• damping down to suppress dust