SaChE Module Fire Hazards

What is the flash point of acetylene?

0F or -18C

deformation of steel can occur with exposure to a heat flux of:

1 kW/m2

Oxygen level in which a person can become unconscious within one minute

10-12%

LOC values for hydrocarbons often used in industrial processes are generally ___.

10-15%

Radiation at the surface of a pool fire is approximately:

100 kW/m2

The NFPA defines a flammable liquid as one whose flashpoint does not exceed ___ when tested by closed cup test methods.

100F

The NFPA defines a combustible material as one that combusts at ___ when tested in a closed cup

100F or higher

what oxygen concentration to people experience impaired judgement and coordination?

17%

a "non-ignitable" atmosphere is commonly defined as less than ___ oxygen.

5%

When oxygen levels are at ___ the person can go into cardiac arrest, have a heart attack or die.

6%

Because there is a lot of variability in reported AIT values, generally, you should use the highest value you can find.

False

Thermal Dose

Flux*Exposure time

UFL (upper flammability limit)

Highest concentration of a substance in air that will sustain combustion

LOC

Limiting Oxygen concentration--> minimum oxygen concentration required to propagate a flame

In general, which is more dangerous, a material with low or high MIE?

Low MIE

Particles

May be irritating to eyes and digestive system and in some cases , actively toxic

in the US, fire hazard prevention and mitigation guidelines are provided by

NFPA and API

Thermal flux is a function of

Not these 3: size, intensity, distance from fire, Also not 2: distance and intensity

following are true:

The LFL decreases as temperature increases The UFL increases as temperature increases

Which materials are combustible?

Wood and synthetic materials

Why is a foam sprinkler system often more effective than a water-based system?

a foam sprinkler coats the fuel, isolating it from air

True statements

another name for full area ventilation is general ventilation, local exhaust ventilation appropriate if limited number of specific sources, local exhaust ventilation sometime augments full area

phosgene

at 10s of ppm, can cause pulmonary edema and death

equipment utilizing an open flame should:

be installed a safe distance from chemical storage, be sufficiently enclosed, and be a safe distance from processing areas

carbon monoxide

can be deadly; replaces oxygen in bloodstream

vapors

can poison if inhaled or absorbed through the skin

what is the most common toxic gas component of smoke?

carbon monoxide

two common methods for testing, closed cup vs open cup, which is preferred?

closed-cup

What was the source of explosion at the BP refinery in Texas City?

combustion engine

The MIE of a solid decreases as the particle size __

decreases

The MIE of a solid _______ as the particle size ______.

decreases, decreases

The flashpoint is usually expressed in ___

degrees C

The hazard zone of longer lasting fires (as opposed to flash fires) can extend far beyond the flame region due to:

exposure time and intensity of the thermal flux

The hazard zone of longer lasting fires can extend far beyond the flame regime due to:

exposure time and intensity of the thermal flux

ventilation rate

expresses in air changes per hour

Due to a flash fire's short duration, combustible materials inside a building within the danger zone are not susceptible to catching fire if the fire initiates outside the building.

false

Most fire related deaths are related to burns.

false

clothing is ineffective at thermal mitigation

false

no sources of electricity should be used in process facilities that utilize flammable materials

false

theoretically, a flammable cloud is the area in which the concentration of flammables it at ore below the LEL

false

to minimize risk of fire from static discharge, nonconductive materials of construction should be used for storage and transfer of flammables

false

how do dikes help prevent and mitigate fires?

fluid kept from flowing to ignition source, reduced evaporation rate = smaller vapor cloud, and consequences of fire in dike mitigated since fire is contained and less likely to spread

what impacts the intensity of a fire?

fuel and type of fire

Local exhaust ventilation is appropriate

if there is a limited number of specific potential sources of flammables in the area

As particle size of a solid fuel is decreased the surface area per mass of fuel ___

increases

Hydrogen cyanide

interferes with cellular respiration

LFL

lowest concentration of a substance in air that will sustain combustion

Flash point

lowest temperature at which a liquid will give off sufficient vapor to be ignited in air. Only defined at P = 1 atm

AIT (autoignition temperature)

lowest temperature at which a material will spontaneously ignite and continue burning in a normal atmosphere

Minimum Ignition energy is usually expressed in units of

millijoules

MIE (minimum ignition energy)

minimum amount of energy required to ignite a combustible vapor, gas, or dust cloud

Steel exposed to a heat flux of greater than ____ can lead to structure failure

not 25 kW/m2

the primary parameter for evaluating the flammability hazard posed by the liquids is the ___.

not MIE

The primary parameter for evaluating the flammability hazard of vapors is called the ____.

not MIE, probably AIT

A pool fire burning under or near a tank of flammable liquid may cause the tank to explode in what is called a ___

not secondary event

the most important parameter in characterizing solid fuels is

particle size

if applicable to the material, the flash point, LFL, UEL, and AIT can commonly be found in _____ of a standard SDS.

physical and chemical properties

What approach to inherently safer design replaces a flammable solvent with a less combustible one?

substitute

in terms of deaths, injuries and property damage, why was the 2013 west fertilizer company event so severe?

the detonation of a large quantity of ammonium nitrate stored at the facility

Select the true statement about thermal flux

thermal flux decreases with the square of the distance from the fire

An LEL monitor may trip safety systems such as the ventilation system

true

Fog-like droplets of liquid within the vapor component of smoke can poison if absorbed through the skin.

true

purging for the purpose of fire prevention involves the use of an inert gas to sweep air or flammables out of lines or equipment.

true

regarding a flash fire hazard, people and material within the danger zone can be exposed to direct flame contact

true

regarding a flash fire, injuries to persons outside of the flammable cloud should be minimal

true

stainless steel tubing can burn in pure oxygen or fluorine if it gets hot enough.

true

the upper flammability limit increases significantly with pressure, enlarging the flammability range.

true

when the air is hot enough, one breath can kill

true