The Flow Of Gases In Furnaces

246

APPENDIX VII

stoppage breaks the seal. Frozen water lines in winter frequently
cause the superintendent to consign the plant to the tropical
regions, particularly when they occur on a cold Sunday morn-
ing. Water vapor absorbed by the flue gases reduces not
only their temperature, but also the stack draft and the
amount of heat available for the waste-heat boiler to convert
into steam.

As to the valve area required for a furnace, there is as much
diversity in practice as there is with the other portions of the
furnace. Figs. 160 and 161 are a graphical comparison of reversing
valve practice, while Table 10 shows the same data in tabular
form. The reference numbers in the table correspond with those
given in preceding chapters.

TABLE 9

REVERSING VALVES

Nominal Diameter Valve
Nominal Area of Valve

In
Ft
nun
Sq In
8(1 Ft,
rn2

18 21 24
1.5Q 1.75 2.00
450 525 610
254 346
452
1,77 2.40 3.14
0.164 0.223 0.292

27 80 33
2.25 2.50
2.75
685 760 840
572 706
855
3.90 4.91 5.93
0.362, 0.456 0.548

36 40 42
3.00 3.33 3.50
915 1000 1070
1017 1256 1385
7.07 8.73 9.62
0.657 0.808 0.894

48 54 60
4.00 4.50 5.00
1220 1370 1525
1809 2290
2827
12.57 15.90 19.63
1.168 1.477 1.823

66
72
5.50 6.00
1675 1830
3421 4071
23.76
28.27
2.210 2.930