Page 19
KN INSTALLATION AND OPERATION INSTRUCTIONS
Gas piping
(continued)
Table 3 Gas flow capacity for black iron pipe
Iron
pipe
size
Pipe length, equivalent feet
(length plus allowance for fittings)
10
20
30
40
50
60
80
100
150
Natural gas pipe flow capacity
(cubic feet per hour)
(notes
1, 2, 3
)
¾”
278
190
152
130
115
105
90
79
64
1”
520
350
285
245
215
195
170
150
120
1 ¼”
1050
730
590
500
440
400
350
305
250
1 ½”
1600
1100
890
760
670
610
530
460
380
Propane gas pipe flow capacity
(cubic feet per hour)
(notes
2, 3
)
¾”
172
118
94
81
71
65
56
49
40
1”
320
220
175
150
135
120
105
95
75
1 ¼”
650
455
365
310
275
250
220
190
155
Notes, Table 3
1
2
3
Natural gas flow capacity is based on 0.60 specific gravity. Refer to the National Fuel Gas Code, ANSI
Z223.1/NFPA 54, for other pressure drops and other specific gravity gases.
The flow rates above allow for a pressure drop of:
Natural gas — 0.30 inches water column, with gas pressure 14 inches water column or less.
Propane — 0.30 inches water column, with gas pressure 14 inches water column or less.
To determine required flow rate in cubic feet per hour for all appliances connected to the gas line:
Natural gas — Divide total Btuh by the gas Btu per cubic foot rating (typically 1,000 Btu/ft
3
nominal).
Propane — Divide total Btuh by 2,500.
Table 4 Equivalent feet of pipe for common gas line components
Iron
pipe
size
Equivalent feet of pipe for each fitting
90° Elbow
Tee
(note
1
)
Gate valve
(note
2
)
Gas cock
(note
2
)
1”
2.6
5.2
0.6
1.5
1 1/4”
3.5
6.9
0.8
1.9
1 1/2”
4.0
8.0
0.9
2.3
2”
5.2
10.3
1.2
3.0
Notes, Table 4
1
2
Allows for flow through the branch of the tee.
Assumes valve is full open.
Gas piping joints
Always use a pipe sealant that is suitable for use
with LP gas. Failure to comply could result in
an explosion, causing possible severe personal
injury, death or substantial property damage.
Only use pipe dope listed for use with propane gas. Even natural
gas may contain some amount of propane.
Use pipe dope sparingly. Excessive pipe dope can block pipe
flow or foul gas train components.
Gas pipe sizing
Required supply pressure at boiler
Minimum gas supply pressure (natural gas or propane), both for
flowing and static conditions:
2 inches
(102 mm)
water column.
Maximum gas supply pressure (natural gas or propane), both
for flowing and static conditions:
14 inches
(356 mm)
water column.
Sizing guidelines
The sizing recommendations of Table 3 are taken from the
National Fuel Gas Code, ANSI Z223.1/NFPA 54. Propane
values are based on adjustment from propane specific gravity
and pressure.
Table 3 allows for a pressure drop from the main supply
regulator to the boiler of 0.3 inches
(7.6 mm)
water column for
natural gas or propane.
For conditions not shown in Table 3, other pressure drops,
or natural gas with other than 0.6 specific gravity, refer to the
appropriate code guidelines for sizing.
Equivalent length
Do not neglect the pressure drop due to pipe fittings.
Equivalent length is the sum of the actual length of piping plus
the total equivalent lengths of all fittings in the line from the
main regulator to the boiler connection. See Table 4 for equiva-
lent lengths of common fittings and components.
Multiple appliances
If more than one appliance is supplied by the same supply
pipe, the piping must be sized based on the maximum possible
demand.
Undersized gas supply piping can cause the
gas line pressure to become negative during
operation of the
KN
boiler. This can cause pilot
outages and operation failures of other appliances
connected to the line, including gas ranges, water
heaters, etc. Failure to properly size the gas lines
can result in potential for severe personal injury,
death or substantial property damage.
Test all gas piping for leaks
All gas piping, components and connections must be leak tested before
putting the boiler in operation. Isolate the boiler from the gas supply
piping if testing with pressure greater than 14 inches
(12.7 mm)
pressure. Failure to do so could result in severe personal injury, death or
substantial property damage.
Check all gas piping components and joints for
leaks. Use either a soap suds mixture, a gas leak
detector or other suitable means.
After testing the system gas piping, remove
the gas valve cover plate on the left side of the
boiler (see illustration at right). Inspect and
leak test around the interior gas line and gas
valve. Replace the cover after completing the
gas connection inspection and testing.
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