Table 3: Specific Gravity other than 0.60
SPECIFIC GRAVITY
MULTIPLIER
0 .50
1 .100
0 .60
1 .000
0 .70
0 .936
0 .80
0 .867
0 .90
0 .816
1 .00
0 .775
PROPANE-AIR
1 .10
0 .740
PROPANE
1 .55
0 .622
BUTANE
2 .00
0 .547
Table 4: Pressure Drop other than 0.3”
PRESSURE
DROP
MULTIPLIER
PRESSURE
MULTIPLIER
0 .1
0 .577
1 .0
1 .83
0 .2
0 .815
2 .0
2 .58
0 .3
1 .000
3 .0
3 .16
0 .4
1 .16
4 .0
3 .65
0 .6
1 .42
6 .0
4 .47
0 .8
1 .64
8 .0
5 .15
Remove all burrs and obstructions from pipe . Do not bend
pipe; use elbows or other pipe fittings to properly locate pipe.
A drip leg must be installed in the vertical line before each
burner such that it will not freeze . Install unions so gas train
components can be removed for service . All pipe threads must
have a pipe dope which is resistant to the action of LP gas .
After installation, pressurize the piping as required and test all
joints for tightness with a rich soap solution . Any bubbling is
considered a leak and must be eliminated . Do not use a match
or flame to locate leaks.
Valve and Regulator Venting
Valve diaphragm vents, pressure regulator vents, and pressure
switch vents are located in the outdoor burner vestibule and
therefore vent tubing is not run to the outside of this vestibule .
If local regulations require that this be done, it is a part of the
field gas piping hookup. Remove any plastic protector plugs
from regulator and valve vents .
Normally Open Vent Valve
Vent valves such as required by IRI for over 1000 MBh input
units must always be routed to the outdoors. This is field
piping .
Gas Piping Routing into Unit
On-The-Roof Piping (Models 020-140)
1 . Remove knockout (1) at corner of burner vestibule door
and saw out corner of door . See
. Make saw cuts
(2) tangent to round hole and square with door edges .
2 . Install pipe corner plate (3) on vestibule, locating on pre-
punched holes . See
. This part is shipped inside
the vestibule with flue box.
3 . Route gas supply pipe through hole . Carefully plan pipe
route and fitting locations to avoid interference with
swinging of doors, etc .
Through-the-Curb Piping
(Models 020-140)
1 . Remove bottom access panel (5) . See
.
2 . Remove knockout (4) and make an opening (6) through
bottom deck directly below knockout hole .
3 . Route gas pipeline through these openings and seal
them off with suitable grommets (7).
Section
A-A .
4 . Replace bottom access panel (5) .
Figure 3: Pipe Routing and Knockout
Figure 4: Pipe Corner Plate
2
1
A
A
2
7
7
4
6
Gas Supply
Section A-A
See
3
4
5
Installation
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7
IM 684-6 • ROOFTOP SYSTEMS
