Gas Piping; Gas Ratings; Specific Gravity Correction Factors - Burnham Revolution Installation, Operating And Service Instructions

VI. Gas Piping
WARNING
Failure to properly pipe gas supply to boiler may
result in improper operation and damage to the
boiler or structure. Always assure gas piping is
absolutely leak free and of the proper size and
type for the connected load.
An additional gas pressure regulator may be
needed. Consult gas supplier.
A.
Size gas piping. Design system to provide adequate gas
supply to boiler. Consider these factors:
1. Allowable pressure drop from point of delivery to
boiler. Maximum allowable system pressure is ½
psig. Actual point of delivery pressure may be less;
contact gas supplier for additional information.
Minimum gas valve inlet pressure is stamped on the
rating label located in the boiler's vestibule com-
partment.
2. Maximum gas demand. Refer to the boiler's input as
printed on it's rating label. Also consider existing
and expected future gas utilization equipment (i.e.
water heater, cooking equipment).
3. Length of piping and number of fittings. Refer to
Table 7 for maximum capacity of Schedule 40 pipe.
Table 8 lists equivalent pipe length for standard
fittings.
Table 5: Gas Ratings
Natural/LP
Maximum
Boiler
Model Number
Gas Pressure
(in. w.c.)
RV3
RV4
RV5
RV6
RV7
USA boilers built for installation at altitudes greater than ,000 feet above sea level have been specially
orificed to reduce gas input rate 4 percent per 1,000 feet above sea level per the National Fuel Gas Code,
NFPA 54/ANSI Z223.1. Canadian boilers' orifice sizing is indicated on the rating label. High altitude boiler
models are identifiable by the model number's ninth digit on the rating label.
48
Minimum Natural
Gas Pressure
(in. w.c.)
Inlet to Gas Valve
4.5
14
(5 = ,001' - 5,000'; D = 5,001' - 9,000')
4. Specific gravity of gas. Gas piping systems for gas
with a specific gravity of 0.60 or less can be sized
directly from Table 7, unless authority having
jurisdiction specifies a gravity factor be applied. For
specific gravity greater than 0.60, apply gravity
factor from Table 6. If exact specific gravity is not
shown choose next higher value.
Table 6: Specific Gravity Correction Factors
Specific
Gravity
0.50
0.55
0.60
0.65
0.70
0.75
0.80
For materials or conditions other than those listed
above, refer to National Fuel Gas Code, NFPA54/ANSI
Z223.1, or size system using standard engineering
methods acceptable to authority having jurisdiction.
B.
Connect boiler gas valve to gas supply system.
Minimum LP
Gas Pressure
(in. w.c.)
Inlet to Gas Valve
11
NOTICE
Correction Specific
Factor Gravity
1.10 1.30
1.04 1.40
1.00 1.50
0.96 1.60
0.93 1.70
0.90 ---
0.87 ---
Natural
Manifold
Pressure
(in. w.c.)
3.5
Correction
Factor
1.07
1.04
1.00
0.97
0.94
---
---
LP
Manifold
Pressure
(in. w.c.)
10