--m
5. GAS PIPING
I Size and install the gas supply piping properly in
order to provide a supply of gas sufficient to meet
the maximum demand without undue loss of
pressure between the meter and the boile_
2 Determine the volume of gas to be provided to the
boiler in cubic feet per hour. To obtain this value,
divide the Btu per hour rating (on the boiler rating
plate) by the heating value of the gas in Btu per
cubic feet. Obtain the heating value of the gas from
the gas supplien As an alternative, use Table 3 or 4
on the next page to obtain the volume of gas to be
provided to the boilen
3 Use the value obtained above as the basis for piping
sizing. Size the gas piping in accordance with Table
5. Consult the National Fuel Gas Code for other
sizing options.
4. Locate the drop pipe adjacent to, but not in front of
the boilen
5.
6.
Install a sediment trap. See Figure 13. Locate a tee
in the drop pipe at same elevation as the gas inlet
connection to the boiler. Extend the drop pipe to a
pipe cap.
Install a ground joint union ahead of the gas control
assembly to permit servicing of the control. Some
local codes require an additional service valve when
using the combination gas controls. If your code
requires such a valve, a suggested location is shown
in Figure 13.
Use a pipe joint sealing compound that is resistant to
the action of liquefied petroleum gas. A non-resistant
compound may lose sealing ability in the presence of
this gas, resulting in a gas leak and fire or explosion
potential.
7. Check piping for leaks prior to placing the boiler in
operation.
Use an approved gas detector, a non-corrosive leak
detection fluid or other leak detection method. If
leaks are found, turn off all gas flow and repair as
necessa W,
I _ SERVICE
VALVE
_--_ JACKET
G.J. UNION
I _ SEDIMENT TRAP
_ FLOOR LINE
Figure 13: Gas Connection to Boiler
8, Disconnect the boiler and its individual shut off valve
from the gas supply piping system during any
pressure testing of that system at test pressure in
excess of 1/2 psig (3.5 kPa).
Do not subject the gas valve to more than 1/2 psi
pressure. Doing so may damage the valve.
Isolate the boiler from the gas supply piping system
by closing its individual service valve during any
pressure testing of the gas supply piping system at
test pressure equal to or less than 1/2 psig (35 kPa)
9. Minimum permissible supply pressure for purposes of
input adjustment (Inches Water Column):
Natura! Gas 5.0"
LP Gas l 1.0"
Maximum permissible supply pressure to the boiler
(Inches Water Column):
Natural Gas 13.5"
LP Gas 13.5"
When checking for leaks, do not use matches,
source of ignition. This can ignite a gas leak,
resulting in fire or explosion.
13
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