Pipe Sizing For Natural Gas - Weil-McLain Ultra Manual

-
gas fired water boiler
Gas piping
Natural Gas:

Pipe sizing for natural gas

1. Size gas piping from meter outlet to entrance
of boiler in accordance with Figure 76 and Fig-
ure 77.
2. Use total input of all boilers. Divide total input
in Btuh by 1,000 to obtain cubic feet per hour of
natural gas.
a. Pipe lengths in Figure 76 are equivalent length
of straight pipe. Convert pipe fittings to equiva-
lent lengths using data from Figure 77.
b. Figure 76 is only for natural gas with specific
gravity 0.60, with a pressure drop through the
gas piping of 0.30" w.c.
c. For additional gas pipe sizing information,
refer to ANSI Z223.1 (or B149.1 or B149.2 for
Canadian installations).
Natural gas supply pressure
1. Pressure required at gas valve inlet pressure port:
a. Maximum: 13" w.c. with no flow (lockup) or
with boiler on
b. Minimum: 5" w.c. with gas flowing (verify dur-
ing boiler startup, while boiler is at high fire)
2. Install 100% lockup gas pressure regulator in supply
line if inlet pressure can exceed 13" w.c. at any time.
Adjust lockup regulator for 13" w.c. maximum.
Propane Gas:
You must follow the instructions, begin-
ning on page 9, to operate the boiler on
propane. Failure to comply could result
in severe personal injury, death or sub-
stantial property damage.
Pipe sizing for propane gas
1. Contact gas supplier to size pipes, tanks and 100%
lockup gas pressure regulator.
Propane supply pressure
1. Adjust propane supply regulator provided by gas
supplier for 13" w.c. maximum pressure.
2. Pressure required at gas valve inlet pressure port:
a. Maximum: 13" w.c. with no flow (lockup) or
with boiler on
• Minimum: 4" w.c. with gas flowing (verify dur-
ing boiler startup, while boiler is at high fire).
Part number 550-100-066/0608
— Boiler Manual
(continued)
Figure 75
Common gas line for multiple boilers
Figure 76
Pipe capacity for 0.60 specific gravity natural gas
Gas pipe Capacity
total length,
1"
feet
10 520
20 350
30 285
40 245
50 215
75 175
100 150
150 120
Figure 77
Equivalent lengths of straight pipe for typical gas line fittings
Pipe size
inches
90° Elbow
1
1¼
1½
2
2½
(cubic feet per hour, 0.60 specific gravity)
1¼" 1½" 2"
1050 1600 3050
730 1100 2100
590 890 1650
500 760 1450
440 670 1270
360 545 1020
305 460 870
250 380 710
Equivalent length, feet
Tee
2.62 5.24
3.45 6.90
4.02 8.04
5.17 10.3
6.16 12.3
2½"
4800
3300
2700
2300
2000
1650
1400
1130
53