Book - School of Science and Technology

Cylinders, indirect cylinders and calorifiers 579PatternBS ref.Dimensions (mm)Heating surface (m 2 )Height DiameterCapacity(litre) Coil Annulus4 450 675 84 0.31 ±5 450 750 95 0.35 ±6 450 825 106 0.40 ±7 450 900 117 0.44 ±8 450 1050 140 0.52 ±9 450 1200 162 0.61 ±9E 450 1500 206 0.79 ±10 500 1200 190 0.75 ±11 500 1500 245 0.87 ±12 600 1200 280 1.10 ±13 600 1500 360 1.40 ±14 600 1800 440 1.70 ±Single feed 3 400 1050 104 0.42 0.635 450 750 56 0.35 0.527 450 900 108 0.44 0.668 450 1050 130 0.52 0.789 450 1200 152 0.61 0.919E 450 1500 196 0.79 1.1810 500 1200 180 0.75 1.13Note: based upon a transmission coefficient of 30 W/m 2 K, the heatingsurface listed is stated to be adequate to raise the temperature of thecylinder contents by 55 K in one hour.application from those fitted elsewhere. This usage is confused by the fact that the formerhad, almost always, an annular heat exchanger whereas the latter were in one form oranother of shell and tube construction. Although the annular type unit has now all butdisappeared, subsequent references here will draw the traditional distinction.Indirect cylindersWith an annular heat exchanger, an indirect cylinder could be installed either horizontallyor vertically. Those cylinders fitted with a helical coil to BS 1566: Parts 1 and 2:1988, as inFigure 20.17, may be preferred from the point of view of differential pressure, primary tosecondary, but there remains some doubt whether or not they suffer from a deficiency inheatingsurface.SecondaryflowSecondaryreturnCold waterfeedHeating coilPrimaryflowPrimaryreturnFigure 20.17 Indirect cylinder with helical coil