Pressure loss in hot water steel piping systems can be estimated from the nomogram below:
The heat flow is based on temperature difference 20oC.
- 1 Pa = 10-6 N/mm2 = 10-5 bar = 0.1020 kp/m2 = 1.02x10-4 m H2O = 9.869x10-6 atm = 1.45x10-4 psi (lbf/in2)
- 1 kW = 1,000 Watts = 3,412 Btu/h = 737.6/550 British hp = 1.341 British hp = 103/9.80665 kgf m/s = 737.6 ft
- 1 liter/s = 10-3 m3/s = 3.6 m3/h = 0.03532 ft3/s = 2.1189 ft3/min (cfm) = 13.200 Imp.gal (UK)/min = 15.852 gal (US)/min = 792 Imp. gal (UK)/h
- 1 m/s = 3.6 km/h = 196.85 ft/min = 2.237 mph
- m (meter) = 3.2808 ft = 39.37 in = 1.0936 yd = 6.214x10-4 mile
Example - Pressure Loss in a Hot Water Heating Pipe
The pressure loss in a 2" BS 1387 hot water heating pipe with heat flow 100 kW can be estimated as indicated below
- With temperature difference 20oC the water flow is 1.2 liter/s
- The flow velocity is 0.54 m/s
- The pressure loss is 60 Pa/m
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