| Maximal flow velocity in pipes |
| Water |
m/s |
ft/s |
| Tap water (low noise) |
0.5 - 0.7 |
1.6 -8.2 |
| Tap water |
1.0 - 2.5 |
3.3 - 8.2 |
| Cooling water |
1.5 - 2.5 |
4.9 - 8.2 |
| Boiler feed water. suction |
0.5 - 1.0 |
1.6 - 3.3 |
| Boiler feed water. discharge |
1.5 - 2.5 |
4.9 - 8.2 |
| Condensate |
1.0 - 2.0 |
3.3 - 6.5 |
| Heating circulation |
1.0 - 3.0 |
3.3 - 9.8 |
| Lower velocity in thin lines. higher in thick
lines. The pressure drop normally calculates separately for longer lines with
several separate bend-resistance´s. |
| Steam |
m/s |
ft/s |
| Saturated Steam. high pressure |
25 - 40 |
82 - 131 |
| Saturated Steam. in special cases |
- 60 |
- 197 |
| Saturated Steam. medium and low pressure |
30-40 |
99 - 131 |
| Saturated Steam. at peak load |
- 50 |
- 164 |
| Steam / Water emulsion |
- 25 |
- 82 |
| The pressure drop normally calculates separately
for longer lines with several separate bend-resistance's. |
| Oil |
m/s |
ft/s |
| Suction lines for pumps |
- 0.5 |
-1.6 |
| Suction lines for pump (low pressure) |
0.1 - 0.2 |
0.3 - 0.65 |
| Discharge line for booster pump |
1.0 - 2.0 |
3.3 - 6.5 |
| Discharge line for burner pump |
- 1.0 |
- 3.3 |
| Air |
m/s |
ft/s |
| Combustion air ducts |
12 - 20 |
40 - 66 |
| Air inlet to boiler room |
1 - 3 |
3.3 - 9.8 |
| Warm air for house heating |
0.8 - 1.0 |
2.6 - 3.3 |
| Vacuum cleaning pipe |
8 - 15 |
26 - 49 |
| Compressed air pipe |
20 - 30 |
66 - 98 |
| Ventilation ducts (hospitals) |
1.8 - 4 |
5.9 - 13 |
| Ventilation ducts (office buildings) |
2.0 - 4.5 |
6.5 - 15 |
| Exhaust gas |
m/s |
ft/s |
| Ducts at minimum load |
- 4.0 |
- 13 |
| Stack at minimum load |
- 5.0 |
- 16 |
| Boiler with one-step burner (on - off) |
5.0 - 8.0 |
16 - 26 |
| Boiler with two-step burner (high - low) |
10 - 15 |
31 - 49 |
| Boiler with modulating burner (3:1) |
15 - 25 |
49 - 82 |
| To keep the surface free from soot the velocity should always
exceed |
3.0 - 4.0 |
9.8 - 13 |
