20
Size of gas supply piping may be larger than heater connection
on installations where a significant run of piping is required.
To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to boiler gas inlet.
Fittings and unions in the gas line must be of the metal to metal type.
Apply joint compounds (pipe dope) sparingly and only to the male
threads of pipe joints. Do not apply compound to the first two
threads. Use compounds resistant to the action of liquefied
petroleum gases.
GAS SUPPLY LINE SIZING
The gas piping installation must be capable of supplying the
maximum probable gas demand without excessive pressure
loss. Depending on local practices, the ALLOWABLE PRESSURE
LOSS between the gas meter, or service regulator and each
appliance is generally 0.3 or 0.5 inches of water column
( 0.075 or 0.124 kPa).
For single boiler installation, refer to table 6 to size iron pipe or
equivalent gas supply line size to be used with single unit.
For multiple boiler installation or installations of a single boiler
with other gas appliances please refer to tables 7 and 8 to size
iron pipe or equivalent gas supply line. These tables are taken
from ANSI Z223.1 NATIONAL FUEL GAS CODE, or
CAN/CSA – B149.1 - 00 (and latest addenda):
•
Table 7 is based on a pressure drop of 0.5 inches water
column (0.124 kPa), and a gas with a specific gravity of 0.60
and a heating value of 1,000 BTU/ft
3
, approximately that of
Natural Gas.
•
Table 8 is based on a pressure drop of 0.5 inches water
column (0.124 kPa), and a gas with a specific gravity of 1.53
and a heating value of 2,500 BTU/ft
3
, approximately that of
Propane Gas.
No additional allowance is necessary for an ordinary number of
fittings. Where it is necessary to use more than the average
number of fittings (i.e., elbows, tees and valves in gas supply
line) use a pipe larger than specified to compensate for increased
pressure drop.
TABLE 6.
SINGLE UNIT INSTALLATION, SUGGESTED GAS PIPE SIZING.
MAXIMUM EQUIVALENT PIPE LENGTH (IN FEET).
Btu
1-1/4"
1-1/2"
2"
2-1/2"
Input
Nat.
Prop.
Nat.
Prop.
Nat.
Prop.
Nat.
Prop.
500,000
40
90
80
200
—
—
—
—
750,000
10
40
40
90
125
—
—
—
1,000,000
—-
20
20
50
70
175
175
—
Natural gas 1000 Btu/ft^
3
, 0.60 specific gravity @ 0.3 in. w.c. pressure drop
Propane gas 2500 Btu/ft^
3
, 1.50 specific gravity @ 0.3 in. w.c. pressure drop.
Table 6
shows the maximum equivalent gas pipe length for a
single unit installation. It does not take into account other
appliances that may be connected to the gas line. For installation
of multiple units, or instances where several appliances are
connected to the same line, use tables 7 and 8 for proper sizing.
WIRING
CAUTION
LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERATION.
FIGURE 15. GAS MANIFOLDS
LB/LW - 1000 NATURAL GAS
LB/LW-500 NATURAL & PROPANE GAS
LB/LW - 750 & 1000 PROPANE GAS
LB/LW-750 NATURAL GAS
FIELD INSTALLED
MAIN MANUAL GAS SHUT-OFF VALVE, DRIP LEG & UNION
Содержание LB 1000
Страница 22: ...22 FIGURE 16 CONNECTION DIAGRAM ...
Страница 23: ...23 FIGURE 17 SCHEMATIC DIAGRAM ...
