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PROCESS SAFETY > CHAPTER 6 - FIRE AND EXPLOSION > Flashcards

CHAPTER 6 - FIRE AND EXPLOSION Flashcards

1
Q

Rapid expansion of gases resulting in a rapidly moving pressure or shock wave

A

d. Explosion

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2
Q

The reaction moves less than the speed of sound in the unreacted medium.

A

c. Deflagration

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3
Q

The gas is dispersed and mixed with air until it comes in contact with an ignition source.

A

a. Unconfined explosion

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4
Q

An explosion resulting from the sudden failure of a vessel containing high-pressure
nonreactive gas.

A

a. Mechanical explosion

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5
Q

It results from the rapid combustion of fine solid particles.

A

c. Dust explosion

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6
Q

Overpressure is a pressure on an object as a result of an impacting shock wave. Dust
Explosion is an abrupt pressure wave moving through a gas.

A

a. First Statement is True.
Second statement is False.

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7
Q

Flashpoint and flammability limits are fundamental properties but are defined only by the specific experimental apparatus and procedure used. The flash point of a liquid is the lowest temperature at which it gives off enough vapor to form an ignitable mixture with air.

A

c. First statement is False.
Second statement is True.

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8
Q

Lower explosion limit (LEL) and upper explosion limit (UEL) are used interchangeably with LFL and UFL. The mixture will not burn when the composition is lower than the lower flammable limit (LFL); the mixture is too lean for combustion.

A

d. Both statements are True

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9
Q

The potential consequences of fires and explosions in pilot plants and the plant
environment are even lesser. The most commonly used method are open cup to determine the flash point.

A

Both statements are False .

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9
Q

Flammability limits for vapors are determined experimentally in a specially designed closed vessel apparatus. Vapor-air mixtures will ignite and burn only over a well specified range of compositions.

A

d. Both statements are True

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9
Q

What is the temperature at which vapor ignites spontaneously from the energy of the environment?

A

c. Autoignition temperature

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10
Q

This indicates the range of fuel concentration that can ignite when mixed with air, and they are often measured in pure oxygen to enhance safety in industrial settings.

A

a. Flammability Limits

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11
Q

What is the process of slow oxygen with accompanying evolution of heat, sometimes
leading to autoignition if the energy is not removed from the system?

A

b. Auto-oxidation

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12
Q

The following are examples of auto-oxidation with a potential for spontaneous
combustion except:

A

c. Clothes soaked with gasoline

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13
Q

What is the minimum oxygen concentration needed to sustain a flame?

A

d. Limiting Oxygen Concentration

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14
Q

What is the general way to represent the flammability of gas or vapor?

A

c. Triangle Diagram

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15
Q

The ____ is the minimum energy input to initiate combustion.

A

b. Minimum ignition energy

16
Q

Liquids with relatively low volatility are more highly to catch fire. Liquids with high
volatility are less likely to catch fire because they self-cool result of evaporation.

A

a. Both statements are true

17
Q

Many hydrocarbons have Minimum Ignition Energies (MIEs) around ____?

A

d. 0.25 mJ

18
Q

The Minimum Ignition Energy (MIE) depends on the following, except:

A

c. Energy

19
Q

What is a blast wave composed of, and what is its primary effect?

A

b. The blast wave is made up of
the pressure wave and
subsequent wind, and it is
responsible for most of the
damage.

20
Q

What is a potential hazard associated with adiabatic compression in processes such as
automobile engines and air compressors?

A

It can cause flammable vapors to ignite if
compressed to temperatures above their
point.

21
Q

What is a key method to prevent fires and explosions involving flammable liquids?

A

c. Identifying and eliminating
as many ignition sources as
possible

22
Q

According to the fire triangle, what must be done to reduce the risk of fire?

A

d. Eliminate ignition soures

23
Q

What can lead to a fire or explosion when mists or sprays are present?

A

b. Static electricity generated during passage orifices

24
Q

How does the lower flammability limit (LFL) change for mechanically formed mists as
drop diameter increases?

A

c. The LFL decreases as drop diameter increases

25
Q

What is primarily responsible for the damage caused by an explosion in many chemical plants?

A

d. The pressure wave created
during the explosion

26
Q

What happens to gas during an explosion?

A

a. It expands rapidly, pushing
surrounding gas outwards

27
Q

What characterizes a confined explosion?

A

b. It occurs in a confined space,
such as a vessel or a building.

28
Q

How does the damage caused by an explosion differ?

A

c. It varies depending on whether it is a detonation or a deflagration.

29
Q

What is the primary purpose of the TNO multi-energy method?

A

b. To estimate the overpressure and impulse of a blast wave

30
Q

What is the purpose of the Sachs-scaled distance in the TNO method?

A

d. To determine the intensity of
the blast wave.

31
Q

How does thermodynamic availability relate to explosion energy?

A

a. It quantifies the maximum useful
work that can be extracted from a
substance.

32
Q

What is the primary driver of the blast wave in a hydrocarbon combustion explosion?

A

c. The release of heat from the
combustion reaction.

33
Q

Which method assumes that the gas expands without any heat transfer?

A

b. Isentropic expansion

34
Q

What is the key assumption in the isothermal expansion method?

A

c. Constant temperature

35
Q

What is a common approach to estimating the blast pressure effects from vessel bursts?

A

c. Subtracting 50% of the total
potential energy

36
Q

What is the primary purpose of Clancey’s formula?

A

a. To estimate the maximum
distance debris can travel

37
Q

What factors influence the behavior of a vapor cloud explosion?

A

d. Quantity of released material
and fraction vaporized

38
Q

What is the immediate consequence of a tank rupture in a BLEVE?

A

b. A rapid vaporization of the
liquid

PROCESS SAFETY (13 decks)

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