Dead Men's Steam School Seminar
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How to Calculate Steam Velocities
Every effort was made to verify the validity of the formulas but we are not responsible for errors and omissions. These do not take the place of engineering calculations. These are rules of thumb. Please consult with the equipment manufacturer for actual requirements.
|
Pipe Sizing to Assure Steam Velocities Below 40 FPS |
||
|
Pipe Size |
Pounds / Hr |
Btu/ Hr |
|
2” |
140 |
134,400 |
|
2 ½” |
199 |
191,200 |
|
3” |
307 |
295,600 |
|
4” |
530 |
509,200 |
|
5” |
833 |
799,600 |
|
6” |
1,204 |
1,155,600 |
|
8” |
2,131 |
2,046,000 |
|
10” |
3,397 |
3,262,000 |
|
12” |
4,783 |
4,592,000 |
|
Pipe Sizing to Assure Steam Velocities Below 50 FPS |
||
|
Pipe Size |
Pounds / Hr |
Btu/ Hr |
|
2” |
175.00 |
168,000 |
|
2 ½” |
248.96 |
239,000 |
|
3” |
384.90 |
369,500 |
|
4” |
663.02 |
636,500 |
|
5” |
1,041.15 |
999,500 |
|
6” |
1,504.69 |
1,444,500 |
|
8” |
2,664.06 |
2,557,500 |
|
10” |
4,247.40 |
4,077,500 |
|
12” |
5,979.17 |
5,740,000 |
How to calculate steam velocity
Lbs/Hr x Cubic Volume of Steam divided by 25 x Internal area of pipe = Steam Velocity
Steam Velocity = Lbs Hour x Cubic Volume of Steam/25 x Internal Area of Pipe
Lbs. Steam/Hr = Btuh/960 Lbs. Steam/Hr = Boiler HP x 34.5 Another formula to calculate steam velocity is:
Steam Velocity = 2.4 x Lbs Hour x Specific Volume of Steam Internal Area of Pipe
|
Volume of Steam in Cubic Feet per Hour |
|
|
PSIG Steam |
Cubic Feet per pound |
|
0 |
27 |
|
1 |
25 |
|
2 |
24 |
|
3 |
22 |
|
4 |
21 |
|
5 |
20 |
|
Internal Volume of Schedule 40 Pipe |
|
|
Pipe Size |
Internal Square Inches |
|
2” |
3.36” |
|
2 ½” |
4.78” |
|
3” |
7.39” |
|
4” |
12.73” |
|
5” |
19.99” |
|
6” |
28.89” |
|
8” |
51.15” |
|
10” |
81.55” |
|
12” |
114.80” |
How Fast is Fast?
One foot per second = 0.6818 miles per hour
The following is a chart to help you to compare the steam velocities.
|
Feet per Second to Miles per Hour |
||||
|
FPS |
MPH |
|
FPS |
MPH |
|
15 |
10.2 |
|
50 |
34.09 |
|
20 |
13.6 |
|
55 |
37.5 |
|
25 |
17 |
|
60 |
40.9 |
|
30 |
20.4 |
|
65 |
44.31 |
|
35 |
23.86 |
|
70 |
47.72 |
|
40 |
27.27 |
|
75 |
51.13 |
|
45 |
30.68 |
|
80 |
54.54 |
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