Bryan Boilers AB Series, Installation, Operation & Service Manual

Page: 8 / 36

TABLE 1.8.1B: STACK EXIT VELOCITY
Estimated STACK EXIT VELOCITY Calculation
(Multiply total ACFM times the velocity factor below velocity in feet per second)
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
6
7
8
10
12
14
16
0.0849
0.0624
0.0477
0.0306
0.0212
0.0156
0.0119 18
20
22
24
26
28
32 0.00943
0.00764
0.00631
0.00531
0.00390
0.00340
0.00298 34
36
38
40
48
60 0.00264
0.00236
0.00212
0.00191
0.00133
0.00085
TABLE 1.8.1C: ESTIMATING FLUE GAS EMISSIONS
Estimated Emissions (Volumetric Flow Rate Per Million Btu/hr Input)
(Multiply PPH listed times boiler input divided by 1,000,000)
BOILER
TYPE
PARTICULATES NOx CO SOx
PPH per
MBH
PPM PPH per
MBH
PPM PPH per
MBH
PPM PPH per
MBH
PPM
Atmospheric Gas
(Draft Diverter)
Atmospheric Gas
(Barometric D.R.)
N/A
N/A
N/A
N/A
0.115
0.115
70
90
0.120
0.120
75
100
N/A
N/A
N/A
N/A
1.8.2 CLEARANCES
The vent system and draft control devices must
be installed so as to achieve the clearances to
surfaces outlined in Table 1.2.1, Minimum
Clearances chart, in this manual. See also Table
1.8.9 for vent clearances. All clearances must
comply with the National Fuel Gas Code
(NFPA54), and with all local and state building codes. The clearances
described in this manual are intended to be
general guidelines only, additional requirements
may occur because of local building design
regulations.
1.8.3 PROTECTION AGAINST DOWNDRAFTS
Because of varying wind conditions and proximity
of adjacent structures, the stack termination may
be exposed to severe downdrafts. If this is
anticipated, provision should be made to supply a
stack cap which will prevent downdrafts. The
Breidert type cap will accomplish this.
Downdrafts will cause ignition problems as well
as expulsion of flue products into the boiler room.