Tables and Calculators

Common Conversions
Enter J/S/KG: Equals: BTU/h/lb

Enter SQ FEET:		 Equals: SQ Meters
Enter SQ Meters: Equals: SQ Feet
Enter MM: Equals: FEET
Enter SQ Inches: Equals: SQ Feet
Enter SQ FEET: Equals: SQ Inches
Enter FEET: Equals: MM
Enter PSI: Equals: Ft of H20
Enter PSI: Equals: HG
Enter GPM(US): Equals: Litres per second
Enter BTUH: Equals: Watts
Enter WATTS: Equals: BTUH
Enter DEG C: Equals: DEG F
Enter DEG F: Equals: DEG C




Air Mix Calculator
Enter Outside Airflow:
Enter Indoor Airflow: Total Airflow
Enter Outside Temp: Enter Indoor Temp:  Mixed Temp




Equivalent Diameters for Rectangular and Round Circular Ducts
The rectangular dimensions and the air flow volume are adapted to the equal friction loss method of sizing ventilation duct systems.  An approximate friction loss of 0.8 inches water gauge per 100 ft duct (6.6 Pa/m) is used.
Air Flow
-q- (Cubic Feet per Minute, CFM)(m3/s)		 Rectangular Duct Sizes
(Inches)		 Equivalent Diameter Round Duct Sizes
- de - (Inches)		 Velocity
- v - (ft/min) (m/s)		 Friction Loss
(Inches water gauge per 100 ft duct)
200
-0.09		 3 x 7
4 x 5 		4.94.9 1527
-7.8 		0.88
300>
-0.14 		4 x 7
5 x 6 		5.7
6 		1635
-8.3 		0.82
400
-0.19 		4 x 9
5 x 7
6 x 6 		6.4
6.4
6.6 		1736
-8.8 		0.8
500
-0.24 		6 x 7 7.1 1819
-9.2 		0.78
750
-0.35 		5 x 12
6 x 10
7 x 8 		8.3
8.4
8.2 		1996
-10.1 		0.77
1000
-0.47 		7 x 10
8 x 9 		9.1
9.3 		2166
-11 		0.79
1250
-0.59 		8 x 10
9 x 9 		9.8
9.8 		2386
-12.1 		0.88
1500
-0.71 		8 x 12
10 x 10 		10.7
10.9 		2358
-11.9 		0.77
1750
-0.83 		8 x 14
9 x 12
10 x 11 		11.5
11.3
11.5 		2469
-12.5 		0.78
2000
-0.94 		8 x 15
10 x 12 		11.8
12 		2589
-13.2 		0.81
2500
-1.2 		10 x 14
12 x 12 		12.9
13.1 		2712
-13.8 		0.8
3000
-1.4 		12 x 14 14.1 2767
-14.1 		0.75
3500
-1.7 		12 x 15 14.6 3010
-15.3 		0.84
4000
-1.9 		10 x 22
14 x 16 		15.9
15.8 		2938
-14.9 		0.73
4500
-2.1 		12 x 19
14 x 16 		16.4
16.4 		3068
-15.6 		0.76
5000
-2.4 		10 x 25
12 x 20
15 x 16 		16.9
16.8
16.9 		3248
-16.5 		0.82
6000
-2.8 		14 x 20
15 x 18 		18.2
17.9 		3358
-17.1 		0.8
7000
-3.3 		12 x 26
16 x 20 		19
19.5 		3482
-17.7 		0.8
8000
-3.8 		12 x 30
14 x 25 		20.2
20.2 		3595
-18.3 		0.8
9000
-4.3 		14 x 34
15 x 25 		21.4
21 		3671
-18.6 		0.78
10000
-4.7 		12 x 36
16 x 25
20 x 20 		21.9
21.7
21.9 		3858
-19.6 		0.83
12500
-5.9 		12 x 45
16 x 30
20 x 24 		24.1
23.7
23.9 		4012
-20.4 		0.8
15000
-7.1 		16 x 36
18 x 30
23 x 25 		24.7
25.2
26.2 		4331
-22 		0.87
17500
-8.3 		16 x 40
20 x 32
25 x 25 		27
27.5
27.3 		4337
-22 		0.79
20000
-9.4 		20 x 35
25 x 28 		28.6
28.9 		4483
-22.8 		0.79
25000
-11.8 		16 x 55
20 x 43
25 x 38 		31
31.5
33.5 		4709
-23.9 		0.78
30000
-14.2 		20 x 50
30 x 32 		33.7
33.9 		4815
-24.5 		0.74
35000
-16.5 		20 x 55
30 x 35 		35.2
35.4 		5179
-26.3 		0.81
40000
-18.9 		25 x 48
30 x 40 		37.4
37.8 		5243
-26.6 		0.77
45000
-21.2 		32 x 40 39.1 5397
-27.4 		0.77
50000
-23.6 		32 x 45
35 x 40 		41.3
40.9 		5222
-26.5 		0.66