Owner's Manual

52
5) The next piping segment, D
7
, serves seven
modules. 7 x 460 = 3220 MBH – Total Input thru
D
7
.
6) Enter Figure 4-3 with 3220 Total Input MBH and
again pick off a pipe/tting size of 4”. Record this
as D
7
.
7) In like manner:
D
6
= 3” D
3
= 2½”
D
5
= 3” D
2
= 2”
D
4
= 3” D
1
, C
1
= 1½”
8) Since all modules require the same input MBH, D
1
– 1½” applies to the vertical drops to each module.
9) From Figure 2-3 the modules’ Gas Connection size
is determined to be 1” MPT (non-IRI assumed for
this example).
10) Record each module’s supply piping (A) and
manual valve (B) sizes as 1”.
11) By inspection the reducing tee ttings © in the
horizontal gas line can be sized based on the
adjacent pipe sizes.
C
8
is between D
8
which is 4” and D
7
which is also
4” and feeds D
1
which is 1½”. Hence C
8
should be
recorded on the drawing as 4” x 4” x 1½”.
12) In like manner:
C
7
= 4 x 3 x 1½ C
4
= 3 x 2½ x 1½
C
6
= 3 x 3 x 1½ C
3
= 2½ x 2 x 1½
C
5
= 3 x 3 x 1½ C
2
= 2 x 1½ x 1½
13) Record all pipe and tting sizes on the gas pipe
drawing for reference during installation.
4.4 Gas Pipe Sizing (Alternate Method)
4.4.1 If all of the conditions for using Figure 4-3 are not
met, the following procedure must be used to size gas
piping:
1) Determine the total equivalent length of pipe from
the meter to the furthest module by adding to the
measured length the equivalent length of each
tting from Figure 4-4. (Straight thru ow through
a tee is not considered a tting).
2) Determine the actual cubic feet of gas to be
carried by the main segment by dividing the BTU
requirement by the heating value of the gas.
3) Determine the equivalent cubic feet of .60 specic
gravity gas by multiplying the actual cubic feet
from 2) above by the appropriate specic gravity
multiplier from Figure 4-6.
4) Enter Figure 4-5 under column for the total
equivalent length of pipe as found in 1) above.
5) Read down until nding a number equal to or
greater than the equivalent cubic feet from 3)
above, which the main segment is required to
carry.
6) Read across to the left hand column and pick off
the minimum pipe size required.
Example #2: Eight 809HE modules are to be piped in
line with propane from a tank source 115 feet from the
furthest module and 8 ells are in the supply line. The
propane to be used has a specic gravity of 1.40 and a
heating value of 2420 Btu/Ft
3
. Size the piping:
a) To the measured length of 115’ add the equivalent
length of 8 ells x 10.1 Ft/Ell for a total equivalent
of 195.8 Ft. (The factor of 10.1 comes from Figure
4-4 under the column for ells at an estimated 4”
main size.)
b) The actual cubic feet required in main D
8
is
8 (modules) x 460,000 (Btu/809HE) = 1521 Ft
3
/Hr
2420 (BTU/Ft
3
)
In a like manner the actual cubic feet required in the
remaining main segments are found to be:
Flow D
7
= 7 x 460,000 ÷ 2420 = 1331 Ft
3
/Hr
Flow D
6
= 6 x 460,000 ÷ 2420 = 1141 Ft
3
/Hr
Flow D
5
= 5 x 460,000 ÷ 2420 = 950 Ft
3
/Hr
Flow D
4
= 4 x 460,000 ÷ 2420 = 760 Ft
3
/Hr
Flow D
3
= 3 x 460,000 ÷ 2420 = 570 Ft
3
/Hr
Flow D
2
= 2 x 460,000 ÷ 2420 = 380 Ft
3
/Hr
Flow D
1
= 1 x 460,000 ÷ 2420 = 190 Ft
3
/Hr
c) Enter gure 4-6 at a specic gravity of 1.40 and
note the multiplier of 1.3. Tabulate equivalent ow
rates for each pipe segment as follows:
Equiv. Flow D8 = 1521 x 1.53 = 2327 Ft
3
/Hr
Equiv. Flow D7 = 1331 x 1.53 = 2036 Ft
3
/Hr
Equiv. Flow D6 = 1141 x 1.53 = 1746 Ft
3
/Hr
Equiv. Flow D5 = 950 x 1.53 = 1454 Ft
3
/Hr
Equiv. Flow D4 = 760 x 1.53 = 1163 Ft
3
/Hr
Equiv. Flow D3 = 570 x 1.53 = 872 Ft
3
/Hr
Equiv. Flow D2 = 380 x 1.53 = 581 Ft
3
/Hr
Equiv. Flow D1 = 190 x 1.53 = 291 Ft
3
/Hr
d) Enter Figure 4-5 from the top at column marked
200 Ft. of pipe. The length found in a) above was
195.8 Ft. which is between column marked 175
and 200 Ft. Use next larger of 200 Ft.
e) Read down until nding a number equal to
or greater than the equivalent cubic foot ow
requirement found in c) above.
f) Read across to the left hand column and pick off
the following required minimum pipe sizes:
Size D
8
= 4”
Size D
7
= 4”
Size D
6
= 4”
Size D
5
= 3”
Size D
4
= 3”
Size D
3
= 2½”
Size D
2
= 2”
Size D
1
= 1½”
g) D1 = 1½” becomes the vertical riser from each of
the modules to the overhead horizontal main.
h) Mark all pipe sizes on the plan for reference during
installation.
4.5 Gas Pipe Installation
With modules fully assembled, including jackets,
install gas supply piping in accordance with the
current edition of “National Fuel Gas Code” (ANSI