Velocity Pressure Method Calculation Sheet
Plant Name: ____________________________ Elevation: _________ Date: ________________
Location: _______________________________ Temp: ____________ Drawing #.:___________
Department: ____________________________+ Factor: ___________ Designer: _____________
1 Duct Segment Identification
2 Target Volume Flowrate, Q = V*A- Chap 10 cfm
3 Min. Transport Velocity, V Chap 10 fpm
4 Maximum Duct Diameter (D= ((4*144*Q)/(pi*V))0.5)inches
5 Selected Duct Diameter inches
2
6 Duct Area (pi*(D/12) /4) sq. ft 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
7 Actual Duct Velocity fpm #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
8 Duct Velocity Pres, VP = (V/4005)2 "wg #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
9 H Maximum Slot Area = (2/11) sq ft
10 O Slot area selected sq ft
11 O S Slot Velocity, Vs Chap 10 fpm
2
12 D L Slot Velocity Pres, VPs=(Vs/4005) "wg 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
13 O Slot Loss Coefficient, Chap 10, Chap 3
14 T Acceleration Factor 0 or 1
15 S S Slot Loss per VP (13+14) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
16 U Slot Static Pressure (12*15) "wg 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
17 C Duct Entry Loss Factor F5-12, Chap 10
18 T Acceleration Factor (1 at hoods) 1 or 0
19 I Duct Entry Loss per VP (17 + 18) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
20 O Duct Entry Loss (8 * 19) "wg #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
21 N Other Losses "wg
22 Hood Static Pressure SPh (16+20+21) "wg #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
23 Straight Duct Length ft
24 Friction Factor (Hf) #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
25 Friction Loss per VP (23 * 24) #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
26 No. of 90 degree Elbows
27 Elbow Loss Coefficient (Bottom of Page)
28 Elbow Loss per VP (26*Loss Factor)(bottom of page)
29 No. of Branch Entries ( 1 or 0)
30 Entry Loss Coefficient
31 Entry Loss per VP (29*Loss Factor) (Branch)
32 Special Fittings Loss Factors
33 Duct Loss per VP (25 + 28 + 31 + 32) #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
34 Duct Loss (8*33) #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
35 Duct SP Loss (22 + 34) #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
36 Other Losses
37 Cumulative Static Pressure "wg
38 Governing Static Pressure (at TO location) "wg
39 Corrected Volumetric Flowrate cfm
40 Corrected Velocity fpm
41 Corrected Velocity Pressure "wg
42 Resultant Velocity Pressure "wg
Q1 Q
PERTINENT EQUATIONS: VPr VP1 2 VP2
Q3 Q3
SPgov .
Qcorr Qdesign
SPduct OR
V 0.533
2
0.4937 Q1 Q2
H f 0.0307 0.612
Q 0.079
Q
V Pr
* D1.066 4005*( A1 A2 ) Branch Entry
Loss Factors
FSP SPoutlet SPinlet VPinlet Angle (*) Factor
Elbow Loss Factors: 10 0.06
FanTP SPout SP VPout VP
in in 60*elbow = 2/3 loss 45oelbow=1/2 loss 30*elbow= 1/3 loss 15 0.09
SP3 SP1 (VP3 V Pr) 20 0.12
R/D 25 0.15
90oelbow 0.5 0.75 1 1.5 2 2.5 30 0.18
Other Information: Stamped 0.71 0.33 0.22 0.15 0.13 0.12 35 0.21
5-piece - 0.46 0.33 0.24 0.19 0.17 40 0.25
4-piece - 0.5 0.37 0.27 0.24 0.23 45 0.28
3-piece 0.9 0.54 0.42 0.34 0.33 0.33 50 0.32
60 0.44
90 1.00
see Fig 5-14
Fig 5-15
Velocity Pressure Method Calculation Sheet
Plant Name: ____________________________ Elevation: _________ Date: ________________
Location: _______________________________ Temp: ____________ Drawing No.:___________
Department: ____________________________+ Factor: ___________ Designer: _____________
1 Duct Segment Identification
2 Target Volume Flowrate, Q = V * A - Chap 10 cfm
3 Min. Transport Velocity Chap 10 fpm
0.5
4 Maximum Duct Diameter (D= ((4*144*Q)/(pi*V)) ) inches
5 Selected Duct Diameter inches
2
6 Duct Area (pi*(D/12) /4) sq. ft
7 Actual Duct Velocity fpm
2
8 Duct Velocity Pres, VP = (V/4005) "wg
9 H Maximum Slot Area = (2/11) sq ft
10 O Slot Area Selected sq ft
11 O S Slot Velocity, Vs Chap 10 fpm
2
12 D L Slot Velocity Pres, VPs = (Vs/4005) "wg
13 O Slot Loss Coefficient , Chap 10, Chap 3
14 T Acceleration Factor 0 or 1
15 S S Slot Loss per VP (13+14)
16 U Slot Static Pressure (12*15) "wg
17 C Duct Entry Loss Factor F5-12, Chap 10
18 T Acceleration Factor (1 at hoods) 1 or 0
19 I Duct Entry Loss per VP (17 + 18)
20 O Duct Entry Loss (8 * 19) "wg
21 N Other Losses "wg
22 Hood Static Pressure SPh (16+20+21) "wg
23 Straight Duct Length ft
24 Friction Factor (Hf)
25 Friction Loss per VP (23 * 24)
26 No. of 90 degree Elbows
27 Elbow Loss Coefficient (Bottom of Page)
28 Elbow Loss per VP (26*Loss Factor)(bottom of page)
29 No. of Branch Entries ( 1 or 0 )
30 Entry Loss Coefficient
31 Entry Loss per VP (29*Loss Factor) (Branch)
32 Special Fittings Loss Factors
33 Duct Loss per VP (25 + 28 + 31 + 32)
34 Duct Loss (8*33)
35 Duct SP Loss (22 + 34)
36 Other Losses
37 Cumulative Static Pressure "wg
38 Governing Static Pressure (at TO location) "wg
39 Corrected Volumetric Flowrate cfm
40 Corrected Velocity fpm
41 Corrected Velocity Pressure "wg
42 Resultant Velocity Pressure "wg
PERTINENT EQUATIONS:
SPgov .
Qcorr Qdesign
SPduct
Q1 Q
VPr VP1 2 VP2
Q3 Q3
V 0.533 0.4937
H f 0.0307 0.612 0.079
Q Q
* D1.066
FSP SPoutlet SPinlet VPinlet 2
Q1 Q2
FanTP SPout SP VPout VP V Pr
4005 * ( A1 A2 )
in in
SP SP (VP V Pr)
3 1 3
Other Information:
Branch Entry Elbow Loss Factors:
Loss Factors 60*elbow = 2/3 loss 45oelbow=1/2 loss 30*elbow= 1/3 loss
Angle (*) Factor
10 0.06 R/D
15 0.09 90oelbow 0.5 0.75 1 1.5 2 2.5
20 0.12 Stamped 0.71 0.33 0.22 0.15 0.13 0.12
25 0.15 5-piece - 0.46 0.33 0.24 0.19 0.17
30 0.18 4-piece - 0.5 0.37 0.27 0.24 0.23
35 0.21 3-piece 0.9 0.54 0.42 0.34 0.33 0.33
40 0.25
45 0.28
50 0.32
60 0.44
90 1.00
see Fig 5-14
Fig 5-15