15
CHECKING GAS PIPING
CAUTION
To prevent personal injury or property
damage due to fire, the following
instructions must be performed regarding
gas connections, pressure testing, location
of shutoff valve and installation of gas
piping.
Before placing in operation, leak test the unit and gas
connections. To avoid the possibility of explosion or fire,
never use a match or open flame to test for leaks. Never
exceed specified pressures for testing. Higher pressure
may damage the gas valve and cause overfiring, resulting
in heat exchanger failure.
This unit and shutoff valve must be disconnected from the
gas supply piping system before supply piping system
pressure testing with test pressures in excess of 1/2 psig
(3.48 kPa).
This unit must be isolated from the gas supply system by
closing its manual shutoff valve before pressure testing of
gas supply piping system with test pressures equal to or
less than 1/2 psig (3.48 kPa).
TANKS AND PIPING - PROPANE GAS UNITS
WARNING
To prevent death, personal injury or property
damage due to fire or explosion caused by
a propane gas leak, install a gas detecting
warning device. Since rust can reduce the
level of odorant in propane gas, a gas
detecting warning device is the only reliable
way to detect a propane gas leak. Contact a
local propane gas supplier about installing
a gas detecting warning device.
WARNING
All metal inserts, screens or turbulators
must be removed from the heat exchanger
tubes when using propane gas. Failure to
comply could cause serious personal injury
or death. Failure to comply with this
requirement will also void warranty
coverage.
All propane gas equipment must conform to the safety
standards of the National Board of Fire Underwriters (See
NBFU Manual 58).
For satisfactory operation, propane gas pressure must be
10 inch WC at the furnace manifold with all gas appliances
in operation. Maintaining proper gas pressure depends on
three main factors:
1. Vaporization rate, depending on temperature of the
liquid, and “wetted surface” area of the container or
containers.
2. Proper pressure regulation. (Two-stage regulation is
recommended for both cost and efficiency).
3. Pressure drop in lines between regulators, and be-
tween second stage regulator and the appliance. Pipe
size will depend on length of pipe run and total load of
all appliances.
Complete information regarding tank sizing for vaporiza-
tion, recommended regulator settings, and pipe sizing is
available from most regulator manufacturers and propane
gas suppliers.
Since propane gas will quickly dissolve white lead or most
standard commercial compounds, special pipe dope must
be used. Shellac base compounds resistant to the actions
of liquefied petroleum gases such as Gasolac, Stalactic,
Clyde’s or John Crane are satisfactory.
Refer to Figure 19 for typical propane gas installations.
Figure 19
Propane Gas Installation (Typ.)
PROPANE GAS PIPING CHARTS
Sizing Between First and Second Stage Regulator
Maximum Propane Capacities listed are based on 2 psig pressure drop at 10 psig setting.
Capacities in 1,000 BTU/hour.
Pipe or
Nominal Pipe Size
Tubing
Tubing Size, O.D. Type L
Schedule 40
Length,
3/8"
1/2"
5/8"
3/4"
7/8"
1/2"
3/4"
Feet
10
730
1,700
3,200
5,300
8,300
3,200
7,500
20
500
1,100
2,200
3,700
5,800
2,200
4,200
30
400
920
2,000
2,900
4,700
1,800
4,000
40
370
850
1,700
2,700
4,100
1,600
3,700
50
330
770
1,500
2,400
3,700
1,500
3,400
60
300
700
1,300
2,200
3,300
1,300
3,100
80
260
610
1,200
1,900
2,900
1,200
2,600
100
220
540
1,000
1,700
2,600
1,000
2,300
125
200
490
900
1,400
2,300
900
2,100
150
190
430
830
1,300
2,100
830
1,900
175
170
400
780
1,200
1,900
770
1,700
200
160
380
730
1,100
1,800
720
1,500
To convert to capacities at 15 psig settings - multiply by 1.130
To convert to capacities at 5 psig settings - multiply by 0.879
