CHAPTER 5 - TOXIC RELEASE AND DISPERSION MODEL

Question 1

A ________ is defined as any gas whose density is greater than the density of the ambient air through which it is being dispersed.

Answer 1

b. Dense gas

Question 2

The dense cloud slumps toward the ground under the influence of ________, increasing its diameter and reducing its height.

Answer 2

a. Gravity

Question 3

A model that was developed by performing a dimensional analysis and correlating existing data on dense cloud dispersion.

Answer 3

c.Britter and McQuaid Model

Question 4

With Eq. 5-64, if the group has a value greater than or equal to 2.5, then the dense gas release is considered as?

Answer 4

a. Continuous

Question 5

With Eq. 5-64, if the group value is less than or equal to 0.6, then the release is considered as?

Answer 5

b. Instantaneous

Question 6

What assumption was made in the Britter-Mcquaid Model about the release of dense gases?

Answer 6

a. occurs at ambient temperature and without aerosol or liquid droplet formation.

Question 7

What was found to have little effect on the results and is not a part of the Britter-Mcquaid model.

Answer 7

d. Atmospheric Stability

Question 8

What is the area that most data of the dispersion tests came from?

Answer 8

c. rural area on flat terrain

Question 9

The model requires a specification of the wind speed, distance downwind, and ambient gas density. At what elevation is required for the wind speed?

Answer 9

b. 10 m

Question 10

As a dense gas moves downstream the concentration ________.

Answer 10

c. Decreases

Question 11

This case is the same as case 2 but with eddy diffusivity as a function of direction. The applicable conditions are:
-Puff release (Qm= constant)
-No wind ((uj)=0), and
- Each coordinate direction has a different but constant eddy diffusivity( Kx,Ky,andKz)

Answer 11

d. Case 5: Puff with No Wind and Eddy Diffusivity Is a Function of Direction

Question 12

This case is the same as case 5 but with wind.he applicable conditions are,
-Puff release (Qm= constant)
-Wind blowing in x direction only (uj)=(ux)=u=constant, and
-Each coordinate direction has a different but constant eddy diffusivity( Kx,Ky,andKz)

Answer 12

b. Case 7: Puff with Wind

Question 13

This case is the same as case 4 but with eddy diffusivity a function of direction. The applicable conditions are:

-Continuous release (Qm= constant)
-Steady State (d(c)/dt=0),
-Wind blowing in x direction only ((uj)=(ux)=u=constant
-Each coordinate direction has a different but constant eddy diffusivity( Kx,Ky,andKz)

Answer 13

a. Case 6: Steady-State Continuous Point Source Release with Wind and Eddy Diffusivity Is a Function of Direction

Question 14

The EPA9 suggests that F stability can exist with wind speeds as low as ____.

Answer 14

a. 1.5 m/s

Question 15

Pasquill-Gifford or Gaussian dispersion applies only to neutrally buoyant dispersion of gasses in which the turbulent mixing is the dominant feature of the dispersion. It is typically valid only for a distance of ______ km from the release point.

Answer 15

a. 0.1–10 km

Question 16

In the Gaussian plume model, what does a “puff” refer to?

Answer 16

b. An instantaneous release of gas in a single, compact cloud.

Question 17

In the Gaussian puff model, what primarily determines the size and shape of the puff over time?

Answer 17

b. Atmospheric stability and wind speed.

Question 18

When applying the Gaussian puff model, what factor is critical in determining the dispersion of the puff over time?

Answer 18

c. The wind speed and direction at the time of release.

Question 19

In dispersion modeling, what does the term “dense gas” specifically refer to?

Answer 19

a. A gas that is heavier than air and tends to stay close to the ground

Question 20

In the context of the Gaussian plume model, what does the term “steady-state” imply?

Answer 20

d. Both the wind conditions and the rate of gas release are constant over time.

Question 21

A process equipment can release toxic materials quickly and in significant enough quantities to spread in dangerous clouds throughout a plant site and the local community during?

Answer 21

b. An Accident

Question 22

Which statement correctly describes the impact of wind speed on the dispersion of a plume or puff according to the Gaussian dispersion models?

Answer 22

a. Higher wind speeds lead to greater dispersion and lower concentrations at a given point.

Question 23

What is the primary effect of atmospheric stability on gas dispersion according to the Gaussian dispersion model?

Answer 23

a. Unstable conditions lead to faster vertical dispersion.

Question 24

Toxic release models are routinely used to _________the effects of a release on the plant and community environments.

Answer 24

a. Estimate

Question 25

Chemical engineers must ___________ all aspects of toxic release to prevent the existence of release situations and to _______ the impact of a release if one occurs

Answer 25

c. Understand ; reduce

Question 26

The toxic release model represents the first ________ steps in the consequence modeling procedure.

Answer 26

b. 3

Question 27

_______________ describe the airborne transport of toxic materials away from the accident site and into the plant and community

Answer 27

c. Dispersion Models

Question 28

Concentrations downwind are ________, because of turbulent mixing and dispersion of the toxic substance with air.

Answer 28

b. Less

Question 29

___________________ relates to vertical mixing of the air.

Answer 29

a. Atmospheric Stability

Question 30

The momentum of a__________ jet will carry the gas higher than the point of release, resulting in a much higher effective release height.

Answer 30

c. Medium-velocity

Question 31

Emergency response planning guidelines (ERPGs) for air contaminants was issued by?

Answer 31

c. AIHA

Question 32

What does TLV stands for?

Answer 32

a. Threshold limit value

Question 33

It is the maximum airborne concentration below which almost everyone believes People could be exposed for up to an hour without feeling or developing permanent or additional severe health consequences or symptoms that might limit their capacity to act in a protective manner.

Answer 33

b. ERPG-2

Question 34

To date, an AIHA peer review task force has produced ____ and is currently reviewing, updating, and expanding them.

Answer 34

a. 47 ERPGs

Question 35

An ____ exposure condition is defined as a condition “that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.”

Answer 35

a. IDLH

Question 36

Since the _____, the National Research Council’s Committee on Toxicology has provided Emergency Exposure Guidance Levels (EEGLs) for ____ chemicals to the Department of Defense.

Answer 36

a. 1940s ; 44

Question 37

For smokestack releases Turner suggested using the empirical ______ formula to compute the additional height resulting from the buoyancy and momentum of the release.

Answer 37

b. Holland

Question 38

38. Risk is composed of both _______ and probability.

Answer 38

b. Consequences

Question 39

Toxic endpoints promulgated by the Environmental Protection Agency (EPA) as part of the _______.

Answer 39

b. RMP

Question 40

They define an _____ toxic concentration as the level of a toxic gas or vapor that could lead to acute health effects

Answer 40

b. Acute