Lecture 16 (Ventilation)

Question 1

IAQ

Answer 1

Remove or control:
Hazardous/ obnoxious odors
Asbestos
Chemicals
Gases etc.

Question 2

IAQ Related illnesses

Answer 2

Pontiac fever
Sinusitis
Legionnaires disease (10-20% mortality)

Question 3

Ventilation Purposes

Answer 3

Provide a continuous supply of fresh outside air
Maintain temperature and humidity at comfortable levels
Reduce potential fire or explosion hazards
Remove or dilute airborne contaminants

Question 4

Ventilation Steps

Answer 4

What the problem is
Location of problem
Type of structure/building layout
Identify source
Locate the source
Is it safe for me and others? 
If unknown or dangerous; follow operation policy

Question 5

Ventilation Types

Answer 5

Vertical: Moving air up and out
Horizontal: Moving air out through windows and doors

Question 6

Ventilation System Types

Answer 6

Local Exhaust Ventilation:
Captures/Removes the contaminant at or near its source
General Dilution Ventilation:
Diluting the concentration of the contaminant(s)

Question 7

Local Exhaust System

Answer 7

There are four elements that make up a local exhaust:
The hood
The ductwork
The air cleaning device
The fan

Question 8

Hood

Answer 8

Captures the contaminant by overcoming its momentum and then drawing it into the system
Velocities Required are:
100 fpm for vapours and gases
200 fpm or more for dusts

Question 9

Duct

Answer 9

Provides a pathway to carry the contaminant to the air cleaning device.
Velocities required are:
1000 fpm for vapours and gases
4000 fpm for heavy dusts

Question 10

Air Flow

Answer 10

Air moves when there is a pressure difference between two locations
Q = VA

Question 11

Natural Air Flow

Answer 11

No cost
Difficult to control
Increased time to utilize

Question 12

Forced Air Flow

Answer 12

Easy to control direction
Need power source
Fumes
Cost

Question 13

Air Cleaning Devices

Answer 13

Mechanical Separators
Filtration Devices
Wet Collectors
Electrostatic Precipitators
Gas Collection
Combustion Incinerators

Question 14

Ventilation Measurements

Answer 14

Smoke Tubes

Anemometers

Question 15

Mechanical Seperators

Answer 15

Gravity chambers
Impingement separators
Cyclone collectors or separators

Question 16

Cyclone collectors or separators

Answer 16

contaminated rotating gas causes particulates to move to the outside of the rotating column
The particulates fall to the bottom and exit through a port
Particles smaller than 5 μm are not collected
Relatively low cost

Question 17

Impingement Separators

Answer 17

Dust-laden air passes through a network of baffles
Particulates have more momentum and cannot make the quick turns
Not used for particles smaller than 20 μm

Question 18

Gravity chambers

Answer 18

low-cost collection devices

works when the air velocity is very slow for large particles

Question 19

Filtration Devices

Answer 19

Mat filters
Ultrafiltration filters
Fabric filters

Question 20

Fabric filters

Answer 20

Air moves through the fabric bags and dust collects inside them
Choose filter based on type of containment and air temperature

Question 21

Ultrafiltration Filters

Answer 21

HEPA remove a wide range of particles
Require considerable maintenance
Have high- pressure drops across them

Question 22

Mat Filters

Answer 22

Made of glass fibers. some are disposable, others are washable