Duct Segment Identification: ab
 Target Volumetric Flow rate (Design) Q = 390cfm (Given)
 Minimum Transport Velocity (Vt) = 4000 fpm (Given)
 Maximum Duct Diameter = 4.23”
Q=V*A
A=Q/V
= 390 / 4000 = 0.375 Sq. ft
A = (Pi * D2)/ 4
Hence D = 4.23”
 Selected Duct Diameter = 4”
We don’t have a diameter of 4.22”. Let’s choose a diameter that is less
than the obtained one and is available.
 Duct Area = 0.0872 sq. ft.
By taking diameter = 4”
 Actual Duct Velocity = 4471.3 fpm
V = Q / Duct Area = 390 / 0.0872
 Duct Velocity Pressure, VP = 1.2464” wg
We know VP = (V / 4005)2
 Maximum Slot Area = N / A
 Slot Area Selected = N / A
 Slot Velocity Pressure = N / A
 Slot Loss Coefficient = N / A
 Acceleration Factor = N / A
 Slot Loss per VP = N / A
 Slot Static Pressure = N / A
 Duct Entry Loss Coefficient = 0.65
For θ = 1800 and rectangular hood loss factor = 0.65 from VS-80-11
 Acceleration Factor = 1
Acceleration Factor is generally taken as 1 for hoods.
 Duct Entry Loss per VP = 1.65
Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor
 Duct Entry Loss = 2.046
Duct Entry Loss = Duct Entry Loss per VP * Duct VP
 Other Losses = N / A
 Hood Static Pressure (SPh) = 2.057
 Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss +
Other Losses
 Straight Duct Length = 15’ (Given)
 Friction Factor (Hf) = 0.0709
From Table 9-4 at V = 4000 fpm and D = 4”
Friction Loss per VP = 1.0635
 No. of 900 degree elbows = N / A
 Elbow Loss Coefficient = N / A
 Elbow Loss per VP = N / A
 No. of Branch Entries = N / A
 Entry Loss Coefficient = N / A
 Entry Loss per VP = N / A
Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient
 Special Fittings Loss Factors = N / A
 Duct Loss per VP = 1.0635
Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry
Loss per VP + Special Fittings Loss Factors
 Duct Loss = 1.3256
Duct Loss = Duct Loss per VP * Duct VP
 Duct SP Loss = 3.382
SP Loss = Hood Static Pressure + Duct Loss
 Other Losses = N / A
 Cumulative Static Pressure = -3.382
 Governing Static Pressure = -3.350’ wg
It is a negative pressure
 Corrected Volumetric Flow rate = N / A
 Corrected Velocity = N / A
 Corrected Velocity Pressure = N / A
 Resultant Velocity Pressure = N / A
Duct Segment Identification: bc
 Target Volumetric Flow rate (Design) Q = 390cfm (Given)
 Minimum Transport Velocity (Vt) = N / A
 Maximum Duct Diameter = N / A






Selected Duct Diameter = N / A
Duct Area = N / A
Actual Duct Velocity = N / A
Duct Velocity Pressure, VP = N / A
Maximum Slot Area = N / A
Slot Area Selected = N / A
 Slot Velocity Pressure = N / A
 Slot Loss Coefficient = N / A
 Acceleration Factor = N / A
 Slot Loss per VP = N / A
 Slot Static Pressure = N / A
 Duct Entry Loss Coefficient = N / A
 Acceleration Factor = N / A
 Duct Entry Loss per VP = N / A
 Duct Entry Loss = N / A
 Other Losses = 2.00
 Hood Static Pressure (SPh) = N / A
Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss +
Other Losses
 Straight Duct Length = N / A
 Friction Factor (Hf) = N / A
 No. of 900 degree elbows = N / A
 Elbow Loss Coefficient = N / A
 Elbow Loss per VP = N / A
 No. of Branch Entries = N / A
 Entry Loss Coefficient = N / A
 Entry Loss per VP = N / A
Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient
 Special Fittings Loss Factors = N / A
 Duct Loss per VP = N / A
Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry
Loss per VP + Special Fittings Loss Factors
 Duct Loss = N / A
Duct Loss = Duct Loss per VP * Duct VP
 Duct SP Loss = 2.00
SP Loss = Hood Static Pressure + Duct Loss
 Other Losses = N / A
 Cumulative Static Pressure = -5.350
 Governing Static Pressure = -5.350’ wg
It is a negative pressure
 Corrected Volumetric Flow rate = N / A
 Corrected Velocity = N / A
 Corrected Velocity Pressure = N / A
 Resultant Velocity Pressure = N / A
Duct Segment Identification: cd
 Target Volumetric Flow rate (Design) Q = 390cfm (Given)
 Minimum Transport Velocity (Vt) = 4000 fpm (Given)
 Maximum Duct Diameter = 4.88”
Q=V*A
A=Q/V
= 390 / 3000 = 0.13 Sq. ft
A = (Pi * D2)/ 4
Hence D = 4.88”
 Selected Duct Diameter = 4.50”
We don’t have a diameter of 4.88”. Let’s choose a diameter that is less
than the obtained one and is available.
 Duct Area = 0.1104 sq. ft.
By taking diameter = 4.5”
 Actual Duct Velocity = 3532.9 fpm
V = Q / Duct Area = 390 / 0.1104
 Duct Velocity Pressure, VP = 0.7781” wg
We know VP = (V / 4005)2
 Maximum Slot Area = N / A
 Slot Area Selected = N / A
 Slot Velocity Pressure = N / A
 Slot Loss Coefficient = N / A
 Acceleration Factor = N / A
 Slot Loss per VP = N / A
 Slot Static Pressure = N / A
 Duct Entry Loss Coefficient = 0.490
For θ = 1800 and rectangular hood loss factor = 0.490 from FIGURE 9-a
Acceleration Factor = 1
Acceleration Factor is generally taken as 1 for hoods.
 Duct Entry Loss per VP = 1.49
Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor
 Duct Entry Loss = 1.159
Duct Entry Loss = Duct Entry Loss per VP * Duct VP
 Other Losses = N / A
 Hood Static Pressure (SPh) = 1.159
 Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss +
Other Losses
 Straight Duct Length = 1.0’ (Given)
 Friction Factor (Hf) = 0.0628
From TABLE 9-4 at V = 3000 fpm and D = 4.5”
Friction Loss per VP = 0.0628
 No. of 900 degree elbows = N / A
 Elbow Loss Coefficient = N / A
 Elbow Loss per VP = N / A
 No. of Branch Entries = N / A
 Entry Loss Coefficient = N / A
 Entry Loss per VP = N / A
Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient
 Special Fittings Loss Factors = N / A
 Duct Loss per VP = 0.0628
Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry
Loss per VP + Special Fittings Loss Factors
 Duct Loss = 0.0489
Duct Loss = Duct Loss per VP * Duct VP
 Duct SP Loss = 1.208
SP Loss = Hood Static Pressure + Duct Loss
 Other Losses = N / A
 Cumulative Static Pressure = -1.208
 Governing Static Pressure = -6.588’ wg
It is a negative pressure
 Corrected Volumetric Flow rate = N / A
 Corrected Velocity = N / A
 Corrected Velocity Pressure = N / A
 Resultant Velocity Pressure = N / A

Duct Segment Identification: ef
 Target Volumetric Flow rate (Design) Q = 390cfm (Given)
 Minimum Transport Velocity (Vt) = 3000 fpm (Given)
 Maximum Duct Diameter = 4.88”
Q=V*A
A=Q/V
= 390 / 3000 = 0.13 Sq. ft
A = (Pi * D2)/ 4
Hence D = 4.88”
 Selected Duct Diameter = 4.5”
We don’t have a diameter of 4.88”. Let’s choose a diameter that is less
than the obtained one and is available.
 Duct Area = 0.1104 sq. ft.
By taking diameter = 4.5”
 Actual Duct Velocity = 3532.9 fpm
V = Q / Duct Area = 390 / 0.1104
 Duct Velocity Pressure, VP = 0.7781” wg
We know VP = (V / 4005)2
 Maximum Slot Area = N / A
 Slot Area Selected = N / A
 Slot Velocity Pressure = N / A
 Slot Loss Coefficient = N / A
 Acceleration Factor = N / A
 Slot Loss per VP = N / A
 Slot Static Pressure = N / A
 Duct Entry Loss Coefficient = N / A
 Acceleration Factor = N / A
 Duct Entry Loss per VP = N / A
 Duct Entry Loss = N / A
 Other Losses = N / A
 Hood Static Pressure (SPh) = N / A
 Straight Duct Length = 10’ (Given)
 Friction Factor (Hf) = 0.0628
From TABLE 5-5 at V = 3000 fpm and D = 8”
Friction Loss per VP = 0. 6280
 No. of 900 degree elbows = N / A
 Elbow Loss Coefficient = N / A
 Elbow Loss per VP = N / A
 No. of Branch Entries = N / A
 Entry Loss Coefficient = N / A
 Entry Loss per VP = N / A
Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient
 Special Fittings Loss Factors = N / A
 Duct Loss per VP = 0.6280
Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry
Loss per VP + Special Fittings Loss Factors
 Duct Loss = .4887
Duct Loss = Duct Loss per VP * Duct VP
 Duct SP Loss = 0.489
SP Loss = Hood Static Pressure + Duct Loss
 Other Losses = N / A
 Cumulative Static Pressure = 0.489
 Governing Static Pressure = N / A
It is a negative pressure
 Corrected Volumetric Flow rate = N / A
 Corrected Velocity = N / A
 Corrected Velocity Pressure = N / A
 Resultant Velocity Pressure = N / A
CALCULATION OF BRAKE HORSE POWER (BHP):
FAN SP = SPout - SPin - VPin
= 0.489 – (-6.588) – 0.7781 = 6.299
FAN TP = SPout + VPout - SPin - VPin
= 0.489 + 0.7781 – (-6.588) – 0.7781 = 7.077
BHP = FAN TP * Q / (6362 * η)
Where:
η = mechanical efficiency (generally taken as 0.9)
BHP = 7.077 * 390 / (6362 * 0.9) = 0.482 hp (select 0.5 hp)