October 21

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

Question 3

What is fire resistance intended to do?

Answer 3

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

Question 4

a fire needs what 4 components to spread

Answer 4

fuel, heat, oxygen, chemical reaction

Question 5

What is the objective in fire resistance?

Answer 5

to limit the routes of fire spread as much as possible

Question 6

how fast can fire spread

Answer 6

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

Question 7

fires spread through 2 main structural routes:

Answer 7

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

Question 8

Fire spread is highly dependent on…

Answer 8

the presence of combustibles in these openings

Question 9

NFPA 704 Diamond - Health Hazard

Answer 9

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

Question 10

NFPA 704 Diamond - Fire Safety (Flash Points)

Answer 10

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

Question 11

NFPA 704 Diamond - Reactivity

Answer 11

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

Question 12

NFPA 704 Diamond - Specific Hazard

Answer 12

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

Question 13

Fires are classified by…

Answer 13

the material that is burning

Question 14

Class A fires

Answer 14

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

Question 15

Class B fires

Answer 15

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)

Question 16

Class C Fires

Answer 16

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)

Question 17

Class D Fires

Answer 17

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

Question 18

why are metal fires so hard to extinguish?

Answer 18

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

Question 19

definition of fire extinguishing

Answer 19

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

Question 20

Portable Fire Extinguishers - Heat removal

Answer 20

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

Question 21

Portable fire extinguishers - removal of oxygen

Answer 21

• 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

Question 22

Portable fire extinguishers - dilution of oxygen

Answer 22

• 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

Question 23

what oxygen concentration levels adversely affect humans

Answer 23

• 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

Question 24

what is back drafting?

Answer 24

the subsequent addition of oxygen that causes an explosion

Question 25

portable fire extinguishers - interruption of the chemical reaction

Answer 25

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

Question 26

Fire extinguishing agents are classified how?

Answer 26

- fire extinguishing agents are classified according to the types of fires on which they are effective

Question 27

Class A Agent (Water)

Answer 27

- 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

Question 28

Class BC Agent (Carbon Dioxide)

Answer 28

- 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

Question 29

Class BC Agent (Ordinary dry chemical powder)

Answer 29

- 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

Question 30

Class ABC Agent (multipurpose dry chemical powder)

Answer 30

- 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

Question 31

Class AB Agent (Foam)

Answer 31

- 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

Question 32

Class D agent (Dry powder)

Answer 32

- 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

Question 33

Class BCD Agent (PKP)

Answer 33

- 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)

Question 34

Smoke detector vs. Sprinkler System?

Answer 34

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

Question 35

Heat Detector

Answer 35

temperature is primary indicator of fire

Question 36

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

Answer 36

- 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

Question 37

flame detector

Answer 37

- monitors the wavelength of light for those most common to fire - susceptible to false readings

Question 38

Gas sensor

Answer 38

use the presence of combustion gases as the primary fire detector

Question 39

Wet-pipe sprinkler system

Answer 39

- 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

Question 40

Dry-Pipe sprinkler system

Answer 40

- 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

Question 41

Pre-action systems

Answer 41

- not pressurized | - use sensors to detect a fire at each head

Question 42

Sprinkler heads may open due to presence of:

Answer 42

- heat - melts a "stop" in the head | - smoke, flame, or gas sensor detection, in the case of the pre-action system

Question 43

in most cases, sprinkler heads detect the fire...

Answer 43

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

Question 44

what is an exit route

Answer 44

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

Question 45

an exit route consists of 3 parts:

Answer 45

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

Question 46

occupant load

Answer 46

- the max # of persons that may be in a building at any time | = (floor area) / (occupant load factor)

Question 47

what is a refuge area

Answer 47

- 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

Question 48

how many exit routes must a workplace have?

Answer 48

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

Question 49

exit routes must be located...

Answer 49

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

Question 50

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

Answer 50

- number of employees - size of building - arrangement of workplace