Book - School of Science and Technology

Chimneys 3250.35650Area of chimney m 20.30.250.20.150.14 m/s5 m/s6 m/s7 m/s8 m/s10 m/s12 m/s600550500450400350Diameter of round chimney mm3000.05250200000.2 0.4 0.6 0.8 1.0 1.2Boiler rating MWFigure 12.4 Chimney areas for stated velocitiesTable 12.3 Pressure loss per metre height of smooth chimney (multiply values by 4 for brick or rough cementrendering)EffectiveChimneydiameter(mm)Pressure loss, (Pa per m height or run) for gas flow at the following velocities (m/s)4 5 6 7 8 9 10 11 12200 0.45 0.71 1.02 1.39 1.81 2.29 2.82 3.41 4.07250 0.34 0.52 0.76 1.02 1.34 1.70 2.10 2.53 3.04300 0.27 0.41 0.60 0.81 1.06 1.35 1.66 2.00 2.39350 0.22 0.35 0.49 0.68 0.88 1.12 1.38 1.67 1.99400 0.18 0.29 0.41 0.56 0.73 0.93 1.14 1.38 1.65450 0.16 0.25 0.36 0.49 0.64 0.81 1.00 1.21 1.44500 0.14 0.22 0.32 0.44 0.57 0.72 0.89 1.07 1.28550 0.13 0.20 0.28 0.38 0.50 0.64 0.78 0.95 1.12600 0.11 0.18 0.25 0.35 0.45 0.57 0.71 0.85 1.02650 0.10 0.16 0.23 0.32 0.41 0.52 0.64 0.78 0.92700 ± 0.14 0.21 0.28 0.37 0.47 0.57 0.69 0.83750 ± 0.13 0.19 0.26 0.34 0.43 0.53 0.64 0.76Velocitypressure 5.4 8.4 12.1 16.5 21.5 27.3 33.6 40.6 48.4