Steam Pipes - Pressure Drop vs. Steam Flow
Pressure drop in steam pipes can be estimated with the diagrams below.
Imperial Units
The diagram is made for steam with pressure 100 psi schedule 40 steel pipe. For other pressures - use correction factors:
| Pressure (psi) | 0 | 5 | 10 | 30 | 60 | 90 | 100 | 110 | 150 | 200 | 250 | 300 |
| Factor | 6.9 | 5.2 | 4.3 | 2.4 | 1.5 | 1.1 | 1.0 | 0.92 | 0.70 | 0.55 | 0.45 | 0.38 |
- 1 lbs/hr = 1.26x10-4 kg/s
- 1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895x10-3 N/mm2 = 6.895x10-2 bar = 27.71 in H2O at 62oF (16.7oC) = 703.1 mm H2O at 62oF (16.7oC) = 2.0416 in mercury at 62oF (16.7oC) = 51.8 mm mercury at 62oF (16.7oC) = 703.6 kg/m2 = 0.06895 atm = 2.307 Ft. H2O
Metric Units
The diagram is made for steam with pressure 7 bar. For other pressures - multiply the pressure drop with correction factors:
| Pressure (bar) | 0 | 1 | 2 | 4 | 5 | 6 | 7 | 8.5 | 10 | 12 | 14 | 20 |
| Factor | 6.9 | 3.67 | 2.51 | 1.55 | 1.31 | 1.13 | 1.0 | 0.85 | 0.74 | 0.63 | 0.55 | 0.39 |
- 1 kg/h = 2.778x10-4 kg/s = 3.67x10-2 lb/min
- 1 bar = 105 Pa (N/m2) = 0.1 N/mm2 = 10,197 kp/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2) = 106 dyn/cm2 = 750 mmHg
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