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safety test 2 > October 21 > Flashcards

October 21 Flashcards

1
Q

Engineering or Administrative Control : putting a timer on machines so that they run at night time

A

Administrative (not engineering b/c you’re not “designing” out the hazard)

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2
Q

if a wall, door, or other building component is rated for 2 hours of fire resistance…

A

it should withstand a fire of certain strength for 2 hours before failure

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3
Q

What is fire resistance intended to do?

A

intended to confine fires while occupants escape and firefighters attempt to extinguish the fire

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4
Q

a fire needs what 4 components to spread

A

fuel, heat, oxygen, chemical reaction

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5
Q

What is the objective in fire resistance?

A

to limit the routes of fire spread as much as possible

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6
Q

how fast can fire spread

A

as fast as 60 mph - this is why forest fires are so dangerous

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7
Q

fires spread through 2 main structural routes:

A
  • horizontal openings (open doors, windows, ventilation ductwork, inside wall and ceiling separations
  • vertical openings (stairways, elevator shafts, laundry chutes)
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8
Q

Fire spread is highly dependent on…

A

the presence of combustibles in these openings

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9
Q

NFPA 704 Diamond - Health Hazard

A 
4 - deadly
3 - extreme danger
2 - hazardous
1 - slightly hazardous
0 - normal material
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10
Q

NFPA 704 Diamond - Fire Safety (Flash Points)

A 
4 - below 73 deg. F
3 - below 100 deg F
2 - below 200 deg F
1 - above 200 deg F
0 - will not burn
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11
Q

NFPA 704 Diamond - Reactivity

A 
4 - may detonate
3 - shock and heat may detonate
2 - violent chemical change
1 - unstable if heated
0 - stable
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12
Q

NFPA 704 Diamond - Specific Hazard

A 
OXY - oxidizer
ACID - acid
ALK - alkali
COR - corrosive
W - use no water
Biohazard symbol - radiation hazard
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13
Q

Fires are classified by…

A

the material that is burning

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14
Q

Class A fires

A

ordinary combustible materials such as wood, paper, cloth, and cardboard that leave an ash residue and burn with a whitish to grayish smoke

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15
Q

Class B fires

A

flammable liquids such as oil, grease, gasoline, paint thinner, and some plastics that will burn with black smoke (due to large amounts of unburned carbon particles)

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16
Q

Class C Fires

A

fires involving energized electrical equipment that give off bueish-white flashes from arcing (normally, once the equipment is deenergized, the fire will cease or become a Class A or Class B fire)

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17
Q

Class D Fires

A

metal fires that burn brightly and give off a white, powdery smoke and may continue to burn in the absence of oxygen

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18
Q

why are metal fires so hard to extinguish?

A

because they seem to defy the tetrahedron (can continue to burn in absence of oxygen)

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19
Q

definition of fire extinguishing

A

removal of heat, oxygen or fuel, or interruption of the chemical chain reaction will stop a fire

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20
Q

Portable Fire Extinguishers - Heat removal

A
  • certain extinguishing agents cool the fuel to below its ignition temp
  • primary example - water
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21
Q

Portable fire extinguishers - removal of oxygen

A
  • some agents establish a barrier between the fuel and the air, thereby depriving the fire of oxygen
  • foam on an oil fire acts in this manner
  • this effect may also be considered as removing the fuel from the fire by isolating the fuel; however, the heat remains with the fuel
22
Q

Portable fire extinguishers - dilution of oxygen

A
  • other agents dilute the air to reduce the concentration of oxygen to below 15% (nominally)
  • below this concentration, fires suffocate due to lack of oxygen
23
Q

what oxygen concentration levels adversely affect humans

A
  • oxygen concentrations below 19.5% adversely affect humans, so great care must be exercised to prevent the fire fighters from becoming a casualty
  • also, the lack of oxygen causes the smoke to be enriched by partially oxidized substances which may be highly toxic and flammable
24
Q

what is back drafting?

A

the subsequent addition of oxygen that causes an explosion

25
Q

portable fire extinguishers - interruption of the chemical reaction

A

dry chemical agents and Halon are thought to interrupt the chemical reaction occurring at the surface of the fuel

26
Q

Fire extinguishing agents are classified how?

A
  • fire extinguishing agents are classified according to the types of fires on which they are effective
27
Q

Class A Agent (Water)

A
  • removes heat, best on Class A fires
  • best overall agent
  • very bad for Class B fires, as it spreads the fuel
  • very bad for Class C fires, as it conducts electricity
  • disastrous on Class D fires, may cause an explosion
28
Q

Class BC Agent (Carbon Dioxide)

A
  • displaces oxygen reducing its concentration to below the level capable of supporting combustion
  • good for class B and C fires
  • not good for Class A fires
  • hazardous to humans
29
Q

Class BC Agent (Ordinary dry chemical powder)

A
  • siliconized sodium bicarbonate
  • airborne powder interrupts the chemical chain reaction
  • does not smother, cool, or remove heat
  • good for Class B and Class C fires
30
Q

Class ABC Agent (multipurpose dry chemical powder)

A
  • siliconized ammonium phosphate
  • performs as ordinary dry chemical powder, plus the powder melts away when it contacts hot surface, sealing the oxygen away from fuel
  • good for Class B and Class C fires
  • fair for class A fires
31
Q

Class AB Agent (Foam)

A
  • water based detergent floats on surface of burning liquids, excluding oxygen from fuel
  • excellent cooling qualities, same as water
  • not suitable for Class C fire
32
Q

Class D agent (Dry powder)

A
  • only for Class D Fires (metal)
  • low velocity, sodium bicarbonate or sand
  • attempts to smother fire; however, some metal fires will continue to burn with no apparent source of oxygen
33
Q

Class BCD Agent (PKP)

A
  • potassium bicarbonate dyed purple to distinguish it from other agents
  • primarily for Class D fires (smothering)
  • it will work on Class B and Class C fires as well (interrupting)
34
Q

Smoke detector vs. Sprinkler System?

A

smoke detector only detects a fire, sprinkler system attempts to put fire out

35
Q

Heat Detector

A

temperature is primary indicator of fire

36
Q

smoke detector - what is it and what kinds are there?

A
  • smoke is primary fire indicator (faster then heat detector)
  • ionization : contains radioactive material that “charges” smoke particles and senses the electrical potential
  • photo-electricity: smoke disrupts a beam of light, similar to an interlock
37
Q

flame detector

A
  • monitors the wavelength of light for those most common to fire
  • susceptible to false readings
38
Q

Gas sensor

A

use the presence of combustion gases as the primary fire detector

39
Q

Wet-pipe sprinkler system

A
  • water is present in the piping system at all times
  • water passes immediately as soon as sprinkler head is opened
  • very quick
  • susceptible to freezing, leaking, and other issues
40
Q

Dry-Pipe sprinkler system

A
  • pipes contain no water
  • may be pressurized with air or nitrogen
  • when sprinkler head is opened, pressure is lost - this loss in pressure opens a valve to release water into system
  • slower then wet pipe systems
41
Q

Pre-action systems

A
  • not pressurized

- use sensors to detect a fire at each head

42
Q

Sprinkler heads may open due to presence of:

A
  • heat - melts a “stop” in the head

- smoke, flame, or gas sensor detection, in the case of the pre-action system

43
Q

in most cases, sprinkler heads detect the fire…

A

detect the fire individually - thus, they don’t all go off at once like in the movies

44
Q

what is an exit route

A

an exit route is a continuous and unobstructed path of exit travel from any point within a workplace to a place of safety

45
Q

an exit route consists of 3 parts:

A
  1. exit access - portion of an exit route that leads to an exit
  2. exit - portion of an exit route that is generally separated from other areas to provide a protected way of travel to the exit discharge
  3. exit discharge - part of the exit route that leads directly outside or to a street, walkway, refuge, area, public way, or open space with access to the outside
46
Q

occupant load

A
  • the max # of persons that may be in a building at any time

= (floor area) / (occupant load factor)

47
Q

what is a refuge area

A
  • a space along an exit route that is protected from the effects of fire by separation from other spaces within the building by a barrier with at least one-hour fire resistance rating, OR
  • a floor with atleast 2 spaces, separated from each other by smoke-resistant partitions, in a building protected throughout by an automatic sprinkler system that complies
48
Q

how many exit routes must a workplace have?

A

a workplace must have at least 2 exit routes to permit prompt evacuation of employees and other building occupants during an emergency

49
Q

exit routes must be located…

A

as far away as practical from each other in case one is blocked by fire or smoke

50
Q

the number of exit routes (2 or more) is based on…

A
  • number of employees
  • size of building
  • arrangement of workplace

safety test 2 (8 decks)

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