22
4801-1020
Super-Saver XL
TM
Heater
8. Pipe Sizing Guidelines
Calculating HVR and ELOP
1. Using a system schematic, label each piping section of the system starting at the meter or regulator.
A different pipe section starts where the gas demand of the system changes, usually at a junction.
2. Determine the Heating Value Required (HVR) in BTUH (BTU’s per hour) for each section of pipe.
HVR = (No. heaters supplied by pipe section) x (Heat output per heater)
3. Determine the Equivalent Length Of Pipe (ELOP) required for sufficient gas service.
ELOP = (Length from meter to most remote heater) + (Minor loss equivalents of the system)
IMPORTANT
:
Use the ELOP value from this equation for size determination of all pipe sections.
4. Use the ELOP value from step 3, and the HVR of each pipe section to determine the required pipe
size for either natural gas (NG) (Refer to Table 1
) or liquid propane (LP) (Refer to
Table 2
) from the table “Maximum Capacity Of Pipe”.
Directions for Reading Pipe Size from Tables
Example: Four 40,000 BTUH (12 kW) heaters will be installed on the gas pipe line as shown in
“Arbitrary Piping System”
NOTE
:
Values given in English and Metric
equivalent units.
1. Determine the HVR value for each pipe section of the system.
2. Determine the ELOP. Length from meter to most remote heater = length from a to e (or g) = 100'
(30 m) + 25' (8 m) = 125' (38 m). Minor loss equivalents from Table 1 = 1 gate valve x 2'/valve
(1 m/valve) + 3 tees x 11'/tee (4 m/tee) = 35' (13 m). Calculated ELOP = 125' (38 m) + 35' (13 m) =
160' (51 m). Tabulated ELOP = 200' (60 m). Round up to the nearest table value.
3. In the appropriate table, NG (Refer to Table 2
) or LP (Refer to Table 3
the column showing the ELOP or the next longer length, if the table does not give the exact length.
Use this column to compare table values to the HVR values. Use the Natural Gas table (Refer to
Table 2
) in this example. From step 2, ELOP = 200' (60 m). Locate the column labeled
200' (60 m) in Table 2
4. Select a pipe section and read down the ELOP column to find the maximum gas capacity that
matches the HVR for that particular pipe section. If the exact value is not listed, choose the next
larger value in the column. In this example, start with pipe section c-e. For pipe section c-e,
HVR = 40,000 BTUH (12 kW). From Table 2
, column 200', 40 (12) is not listed.
(
NOTE
:
The table values are in thousands of BTUH’s.
) The next larger value of 72 (21) is read from
the table, corresponding to 72,000 BTUH (21 kW).
Pipe Section
# of Heaters
HVR Calculation
HVR Value
BTUH
kW
BTUH
kW
a-b
4
4 x 40,000
4 x 12
160,000
48
b-c
2
2 x 40,000
2 x 12
80,000
24
c-e
1
1 x 40,000
1 x 12
40,000
12
b-d
1
1 x 40,000
1 x 12
40,000
12
b-f
1
1 x 40,000
1 x 12
40,000
12
c-g
1
1 x 40,000
1 x 12
40,000
12
