Industrial Ventilation vs. IAQ

1
Industrial Ventilation vs. IAQ
Heating Ventilation Air Conditioning
2
Industrial Ventilation vs. IAQ
24
3
Industrial Ventilation vs. IAQ
4
Industrial Ventilation vs. IAQ
5
Routes of Entry

• Inhalation
• Ingestion
• Absorption
• Injection

6
Control Options

• Process change
• Substitution
• Isolation
• Ventilation
• Administrative control
• Personal protective equipment

7
Problem Characterization
AIRFLOW
EMISSION SOURCE
BURTON 2-1
8
Burton Ex. 2-1

• GROUP EXERCISE
• Study the figure on page 2-4 and discuss
  potential control measures that you might use to
  correct the problem.

BURTON 2-4
9
THE BEHAVIOR OF AIR
10
The Atmosphere

• Reaches 50 miles into space.
• Pressure 14.7 pounds per square inch.

11
Composition of Air
12
Pressure Measurement
Vacuum
Atmospheric Pressure 14.7 psia
13
Pressure Measurement
14.7 psia 407in. Water
14.7 psia 29.92 in. Mercury (Hg.)
14
How Do We Make Air Move ?
15
Pressure

• Differences in air pressure cause movement.

16
Pressure Differential Causes Movement
FLOW
LOW
HIGH
FAN
BURTON 3-6
17
Negative Pressure Less Than Atmospheric
18
Positive Pressure Greater Than Atmospheric
19
Pressure Relationships
20
Pressure Terms

• Static Pressure
• Velocity Pressure
• Total Pressure

21
Static Pressure
Flow
SP
Static pressure (SP) is exerted in all directions.
22
Velocity Pressure
Flow
SP
VP
Velocity Pressure (VP) is kinetic (moving
pressure) resulting from air flow.
23
Total Pressure
Flow
SP
VP
TP
Total pressure (TP) is the algebraic sum of the
VP and SP.
24
Pressure Upstream and Downstream of the Fan

• TP SP VP
• Up-stream - -
• Down-stream

BURTON 3-8
25
What is use of the term Velocity Pressure ?

• Determine the air flow.
• To design the system.
• V 4005(VP)1/2

26
What is use of the term Static Pressure ?

• Accelerate the air.
• Overcome resistance to friction.

27
Static Pressure and Velocity Pressure are
Mutually Convertible
When air is accelerated, the static pressure is
converted to velocity pressure.

When air is decelerated, the velocity pressure
can be transformed back into static pressure.
28
Conservation of Mass

• Mass in Mass out.
• Air speeds up when the duct area is smaller.

Q VA Q Cubic Feet Per Minute V Velocity A
Area
29
Dilution Ventilation

• YES
• non-hazardous
• gas, vapor, respirable particle
• uniform time emission
• emissions not close to people
• moderate climate

• NO
• toxic material
• large particulate
• emission varies widely over time
• large, point source emissions
• people in vicinity
• severe climate
• irritation or complaints

BURTON 4-1
30
Volume Vapor Flow Rate

BURTON 4-3
31
Estimating Dilution Air Volume

BURTON 4-5
32
Poor Dilution
33
Good Dilution
34
Example 4-1

• What is q, the volume flow rate of vapor
  formed, if 0.5 gallons of toluene are evaporated
  uniformly over an 8-hr. shift? What volume flow
  rate Qd is required for dilution to 10 ppm, if
  Kmixing 2 ? (Assume STP d 1.0)
• What is the average face velocity of air in a
  room 10ft. 8ft. 40ft for these conditions?

BURTON 4-6
35
Strategy Ex. 4-2

• Step 1 Calculate the volume flow rate of the
  vapor
• emitted q.
• q (387 lbs. evaporated)/ (MW
  t d)
• Notelbs. Evaporated
  gal. 8.31 SG
• Step 2. Calculate the dilution air volume flow
  rate
• Qd.
• Qd q 106 K mixing
• 
  Ca (ppm)
• Step 3 Calculate the face velocity.
• V face Qd/A
• Step 4 Calculate the air changes/ hour.
• N (Qd 60)/Vr

36
Purge and Buildup

• Purge and buildup - predict contaminant buildup
  or purge rate.
• Steady state -equilibrium maintained.

BURTON 4-9
37
Example 4-5

• An automobile garage was severely contaminated
  with carbon monoxide.
• How long will it take to purge the garage?

BURTON 4-11
38
Chapter 11 - Makeup Air Balance

• Exhausted air must be replaced.
• Negative pressure without makeup air.

BURTON 11-1
39
Make up Air

• Fresh air supplied into the breathing zone of the
  associate.

40
Overcoming Negative Static Pressure

• Changes in static pressure involving radial
  (squirrel cage) fans cause a small change in the
  volumetric flow rate.

• Changes in static pressure involving axial
  (propeller) fans cause a large change in the
  volumetric flow rate.

BURTON 11-2
41
Good Makeup Air
INDUSTRIAL VENTILATION 2-4
42
Bad Makeup Air
INDUSTRIAL VENTILATION 2-4
43
Reentrainment
BURTON 11-9
44
Reentrainment
BURTON 11-9
45
Avoiding Reentrainment10-50-3000 RULE
BURTON 14-5
46
Recirculation of Exhaust Air

• Good for non-toxic particulate control.
• Can recover 40-60 of heat energy.

BURTON 12-1
47
Types of Ventilation Systems
BURTON 5-1
48
Why Choose Local Ventilation?

• No other controls
• Containment
• Employee in vicinity
• Emissions vary with time
• Sources large and few
• Fixed source
• Codes

BURTON 5-2
49
Exercise 5-3

• Form your group and try exercise 5-3. Compare
  the operation to the parameters listed below
• No other controls available
• Hazardous contaminant
• Employee in immediate vicinity
• Emissions vary with time
• Emission sources large and few
• Fixed emission source
• Codes standards

BURTON 5-3
50
Components of a Local Exhaust System
BURTON 5-4
51
Static Pressure Review
BURTON 5-5
52
Energy Conservation
BURTON 5-6
53
Basic Air Flow Equations

• Q V A
• TP SP VP
• V 4005(VP/d)0.5

BURTON 5-7
54
Static Pressure Loss

• Static Pressure Loss Kloss VP d

BURTON 5-8
55
Elbow Loss

• Air moving through elbows spends static
  pressure because of
• directional change
• friction
• shock losses
• turbulent mixing
• air bunching up
• SP(loss) K(elbow ) VP d

BURTON 5-9
56
Elbow Loss Ex. 5-8

• What is the elbow loss factor K(elbow) where
  the elbow radius of curvature is R/D 2.0 in a
  smooth transition elbow.

BURTON 5-9
57
Elbow Loss Exercise 5-9

• What is the actual loss in inches of water of
  air flowing through a 60-degree, 3-piece elbow at
  V 3440 fpm? R/D 1.5, STP, d1.

BURTON 5-10
58
Elbow Loss Exercise 5-9

• SPloss K VP d
• Use Chart 13, Appendix pg. 25 for information on
  a 90-degree 3- piece elbow with R/D 1.5
• Let K (angle/90) K 90
• VP (V/4005)2

59
Friction Loss as a Function of Duct Length

• Friction Loss K VP L R d
• K is a value taken from Chart 5,
• appendix page 9
• VP is duct velocity pressure, in w.g.
• L is the length of the duct in feet
• d is the density correction factor
• R is roughness correction factor

BURTON 5-11
60
Exercise 5-10

• What is the friction loss for a length of
  galvanized duct with the following parameters? D
  8in., Q 1000scfm, L 43 ft. R 1.

61
Tee Losses
BURTON 5-11
62
Tee Losses Ex. 5-12

• What is the estimated static pressure loss in
  inches of water for a branch entry of 30 degrees
  where the branch entry velocity is 4500 fpm?

BURTON 5-12
63
Converting Static Pressure To Velocity Pressure

• At the hood, all of the available static
  pressure is converted to velocity pressure and
  hood entry loss.
• ?SPh ? VP he

BURTON 6-2
64
Measuring Hood Static Pressure

• Measure hood static pressure 4-6 duct
  diameters downstream from the hood.

4-6 D
BURTON 6-2
65
Hood Entry Losses

• The hood entry loss is the sum total of all
  losses from the hood face to the point of
  measurement in the duct.
• SP(loss) K VP d
• he K VP d

BURTON 6-2
66
Example 6-1

• What is the hood static pressure when the duct
  velocity pressure is VP 1.10 in. w.g. and the
  hood entry loss is
• he 1.00 in w.g.
• ?SPh ? VP he
• ?SPh ? 1.10 1.00
• -2.10 in w.g.

BURTON 6-3
67
Vena Contracta

• The greatest loss normally occurs at the
  entrance to the duct, due to the vena contracta
  formed in the throat of the duct.

BURTON 6-3
68
Hood Efficiency

• A hoods efficiency can be described by the
  ratio of actual to ideal flow. This ratio is
  called the Coefficient of Entry, Ce.
• Ce Q(actual)/Q(ideal)

BURTON 6-4
69
Hood Static Pressure and Entry Losses Example 6-5

• The average velocity in a duct serving a hood
  is V 2000 fpm. The loss factor for the hood
  has been obtained from the manufacturer as Khood
  2.2. What are the he and SPh? (Assume STP,
  d 1)

BURTON 6-5
70
Hand Grinding Table Example 6-6

• Assume that a special hand grinding table
  hood has been built and the following data have
  been measured
• SPh -2.50 in w.g., V 4000fpm, and the
  duct diameter is 18 in. (Assume STP, d1)

BURTON 6-6
71
Types of Hoods

• Receiving
• Capturing
• Enclosing

BURTON 6-10
72
Hood Types

• SLOTTED HOOD

73
Hood Types

• ENCLOSED HOOD

74
Hood Types

• ENCLOSING HOOD

75
Hood Types

• CAPTURING HOOD

76
Grinding Wheel Hood Example Example 6-9

• Determine the volume flow rate, transport
  velocity, duct diameter, loss factor K, Ce, he,
  and SPh, for a grinding wheel hood, wheel
  diameter 13in. (low surface speed), straight
  take off sto, STP)

BURTON 6-12
77
EXERCISE 6-10USEFUL FORMULAS

• Q V A
• V 4005(VP)1/2
• VP (V/4005)2
• he K VP
• ?SPh ? VP he

BURTON 6-12 AND 6-13
78
Exercise 6-10a

• Where appropriate, determine the volume flow
  rate, transport velocity, duct diameter, loss
  factor K, Ce, he, and SPh for a grinding wheel
  hood with a wheel diameter of 14 in. (low surface
  speed, tapered takeoff tto. Note the picture
  in the book is for a buffing hood.

BURTON 6-12
79
Exercise 6-10a Strategy

• 1. Use Chart 11C, appendix pg. 18 to find Q,
  Vtrans., K, and Ce.
• 2. Use Chart 5A in appendix pg. 9 to find the
  diameter of the pipe needed and its area.
• 3. Calculate Vactual Q/A
• 4. VP (Vactual/4005)2
• 5. he K VP
• 6. ?SPh ? VP he

80
Exercise 6-10b

• Where appropriate, determine the volume flow
  rate, transport velocity, duct diameter, loss
  factor K, Ce, he, and SPh for a hand grinding
  table 10 feet long by 2 feet wide.

BURTON 6-13
81
Exercise 6-10b Strategy

• 1. Use Chart 11C, appendix pg. 18 to find Q,
  Vtrans., K, and Ce.
• 2. Use Chart 5A in appendix pg. 9 to find the
  diameter of the pipe needed and its area.
• 3. Calculate Vactual Q/A
• 4. VP (Vactual/4005)2
• 5. he K VP
• 6. ?SPh ? VP he

82
Exercise 6-10c

• Where appropriate, determine the volume flow
  rate, transport velocity, duct diameter, loss
  factor K, Ce, he, and SPh for a band saw used to
  cut wood that has a blade width of 1 inch.

BURTON 6-13
83
Exercise 6-10c Strategy

• 1. Use Chart 11E, appendix pg. 20 to find Q,
  Vtrans., K, and Ce.
• 2. Use Chart 5A in appendix pg. 9 to find the
  diameter of the pipe needed and its area.
• 3. Calculate Vactual Q/A
• 4. VP (Vactual/4005)2
• 5. he K VP
• 6. ?SPh ? VP he

84
Exercise 6-10d

• Where appropriate, determine the volume flow
  rate, transport velocity, duct diameter, loss
  factor K, Ce, he, and SPh for a bell-mouthed hood
  used for welding. X10 in., Vc 100 fpm, Vtrans
  3000 fpm.

BURTON 6-13
85
Exercise 6-10d Strategy

• 1. Use Chart 11A, appendix pg. 16 to find Q, K,
  and Ce.
• 2. Use Chart 5A in appendix pg. 9 to find the
  diameter of the pipe needed and its area.
• 3. Calculate Vactual Q/A
• 4. VP (Vactual/4005)2
• 5. he K VP
• 6. ?SPh ? VP he

86
Exercise 6-10e

• Where appropriate, determine the volume flow
  rate, transport velocity, duct diameter, loss
  factor K, Ce, he, and SPh for a canopy hood used
  for a hot-liquid open surfaced tank. P 16 ft.,
  X 3 ft., Vcontrol 125 fpm, Vtrans 2000fpm.

BURTON 6-13
87
Exercise 6-10e Strategy

• 1. Use Chart 11B, appendix pg. 17 to find Q, K,
  and Ce.
• 2. Use Chart 5A in appendix pg. 9 to find the
  diameter of the pipe needed and its area.
• 3. Calculate Vactual Q/A
• 4. VP (Vactual/4005)2
• 5. he K VP
• 6. ?SPh ? VP he

88
Factors Influencing Hood Performance

• Competition
• Mixing
• Work practices

BURTON 6-17
89
Canopy Hoods

• Use only for hot processes with rising air.
• Estimate initial and terminal velocities of
  rising air stream.
• The volume of air exhausted from the hood must
  exceed the volume of air arriving at the hood
  face.
• Warm rising air expands as it rises. Make the
  cross-sectional area of the hood face 125 larger
  than the plume of hot air.
• Avoid canopy hoods if an employee must work over
  the source.

BURTON 6-19
90
Chapter 7Selection and Design of Ductwork
BURTON 7-1
91
Exercise 7-2

• Standard air (d1) moves through an 8 in.
  galvanized duct system at 4000 fpm. Estimate VP,
  find the loss factors K from the Charts, and then
  estimate static pressure loss for each component
  in each branch. (Note treat the branch entry as
  two 45-degree entries and use the ACGIH value for
  K on Chart 14.)

BURTON 7-4
92
Exercise 7-2a, Flanged Hood

BURTON 7-4
93
Exercise 7-2b, Plain Duct Hood

BURTON 7-4
94
Exercise 7-2c, Elbow, 3-piece

BURTON 7-4
95
Exercise 7-2d, Elbow, 5-piece

BURTON 7-4
96
Exercise7-2e, Elbow, 4-piece

BURTON 7-4
97
Exercise 7-2f, Branch Entry

BURTON 7-4
98
Exercise 7-2g, 50 ft. of Duct

BURTON 7-4
99
RoughnessExample 7-1

• Standard air is flowing in 40 feet of a 24 in.
  concrete pipe at the 4000 fpm. What is the
  correction factor, R? The loss factor K?

BURTON 7-5
100
Duct Shapes

• Use round duct whenever possible, it resists
  collapsing, provides better aerosol transport
  conditions, and may be less expensive.

BURTON 7-6
101
Pressure Diagrams
BURTON 7-11
102
Chapter 8 Fan Selection and Operation

• AXIAL FANS
• propeller fans

• CENTRIFUGAL FANS
• radial fans
• forward inclined
• backward inclined

BURTON 8-2
103
Fan Total Pressure

• The fan total pressure (FTP) represents all
  energy requirements for moving air through the
  ventilation system.
• The fan total pressure is often referred to
  as the fan total static pressure drop.
• FTP TP outlet - TP inlet
• FTP SPout - VP out - SPin - VP in
• FTP SPout - SPin

BURTON 8-3
104
Exercise 8-1

• Find the Fan Total Pressure given that the
  SPin -5.0 in w.g, SPout 0.40 in w.g.
• VPin VPout 1.0 in. w.g.
• FTP SPout - SPin
• 0.40 - (-5.0) 5.4 in w.g.

BURTON 8-3
105
Exercise 8-2Fan Static Pressure

• The fan static pressure out of the fan is
  defined as the fan total pressure minus the
  average velocity pressure out of the fan.
• FSP Fan TP - VPout

BURTON 8-4
106
SOP and Fan Curves

• To develop a system curve, the fan should be
  turned at different rpms and the flow and the
  absolute values of the static pressures at the
  fan are plotted.

BURTON 8-5
107
Developing Fan Curves
BURTON 8-6
108
SOP on Steep Part of Curve
BURTON 8-7
109
Example 8-1

• Choose an appropriate fan for a system
  operating point of Q 10,000 scfm and FTP 1.5
  in. w.g.

BURTON 8-8
110
Exercise 8-3

• Find a fan and appropriate rpm for a fan
  exhausting 15,000 cfm at a fan TP 2.0 in. w.g.

BURTON 8-8
111
Exercise8-4

• Find a suitable fan and the appropriate rpm
  for a ventilation system exhausting 480 cfm at a
  fan TP 13.8 in. w.g.

BURTON 8-8
112
Commercial Fan Curves
BURTON 8-9
113
Commercial Fan Curves
BURTON 8-10
114
Commercial Fan Curves
BURTON 8-11
115
System Effect Losses
BURTON 8-12
116
Six-and-Three Rule
BURTON 8-13
117
Air Horsepower

• Air horsepower refers to the minimum amount
  of power to move a volume of air against the fan
  total pressure. It represents the power to get
  the air through the duct system.
• ahp ( FTP Q d)/6356

BURTON 8-14
118
Brake Horsepower

• Brake horsepower refers to the actual power
  required to operate the fan so that it fulfills
  the job of moving the specified cfm against the
  FTP. It takes into account fan inefficiencies,
  i.e. losses in the fan.
• bhp ahp/ME

BURTON 8-15
119
Shaft Horsepower

• Shaft horsepower is bhp plus any power
  required for drive losses, bearing losses, and
  pulley losses between the fan and the shaft of
  the motor.
• shp bhp Kdl

BURTON 8-15
120
Rated Horsepower

• Rated horsepower is the nameplate horsepower on
  the motor.

BURTON 8-15
121
Example 8-4

• What is the required power for the system and
  what rated power motor would you use?
• FTP 5.0 in. w.g. ,
• Q 12000 scfm
• ME 0.60, Kdl 1.10, d 1,
• f 6356

BURTON 8-16
122
Exercise 8-7

• Estimate the ahp, bhp, shp, and the rated
  power motor you would choose for the following
  system.
• Fan TP 10.0 in. w.g.,
• Q 5000 scfm
• Kdl 1.15, STP(d1),
• f 6356, ME 0.65

BURTON 8-17
123
Fan Laws
BURTON 8-19
124
Local Exhaust Ventilation Design
BURTON 9-1
125
Plenum Design
BURTON 9-3
126
BALANCING

• Balancing during the design phase means
  adjusting losses in duct runs leading to a
  junction that the predicted loss in each run is
  essentially equal.

BURTON 9-4
127
Example 9-2

• Design an local exhaust system based on the
  criteria listed in the example.

BURTON 9-5
128

129
Example 9-3

• Design a local exhaust system based upon the
  criteria listed on this page.

BURTON 9-11
130
(No Transcript)