Sterling QVSB - Manual (Page 7)

7
Maximum Capacity of Pipe in Cubic Feet of Gas per Hour (Cubic Meters per Hour) for Gas Pressures of 0.5 psig (3.5 kPa) or Less,
and a Pressure Drop of 0.5 Inch Water Column (124.4 Pa)
(Based on a 0.60 Specifi c Gravity Gas)
Nominal
Iron Internal Length of Pipe, Feet (meters)
Pipe Size Dia. 10 20 30 40 50 60 70 80 90 100 125 150 175 200
in. in. (3.0) (6.1) (9.1) (12.2) (15.2) (18.3) (21.3) (24.4) (27.4) (30.5) (38.1) (45.7) (53.3) (61.0)
1/2 0.622 175 120 97 82 73 66 61 57 53 50 44 40 37 35
(4.96) (3.40) (2.75) (2.32) (2.07) (1.87) (1.73) (1.61) (1.50) (1.42) (1.25) (1.13) (1.05) (0.99)
3/4 0.824 360 250 200 170 151 138 125 118 110 103 93 84 77 72
(10.2) (7.08) (5.66) (4.81) (4.28) (3.91) (3.54) (3.34) (3.11) (2.92) (2.63) (2.38) (2.18) (2.04)
1 1.049 680 465 375 320 285 260 240 220 205 195 175 160 145 135
(19.3) (13.2) (10.6) (9.06) (8.07) (7.36) (6.80) (6.23) (5.80) (5.52) (4.96) (4.53) (4.11) (3.82)
1 1/4 1.380 1400 950 770 660 580 530 490 460 430 400 360 325 300 280
(39.6) (26.9) (21.8) (18.7) (16.4) (15.0) (13.9) (13.0) (12.2) (11.3) (10.2) (9.20) (8.50) (7.93)
1 1/2 1.610 2100 1460 1180 990 900 810 750 690 650 620 550 500 460 430
(59.5) (41.3) (33.4) (28.0) (25.5) (22.9) (21.2) (19.5) (18.4) (17.6) (15.6) (14.2) (13.0) (12.2)
2 2.067 3950 2750 2200 1900 1680 1520 1400 1300 1220 1150 1020 950 850 800
(112) (77.9) (62.3) (53.8) (47.6) (43.0) (39.6) (36.8) (34.5) (32.6) (28.9) (26.9) (24.1) (22.7)
2 1/2 2.469 6300 4350 3520 3000 2650 2400 2250 2050 1950 1850 1650 1500 1370 1280
(178) (123) (99.7) (85.0) (75.0) (68.0) (63.7) (58.0) (55.2) (52.4) (46.7) (42.5) (38.8) (36.2)
3 3.068 11000 7700 6250 5300 4750 4300 3900 3700 3450 3250 2950 2650 2450 2280
(311) (218) (177) (150) (135) (122) (110) (105) (97.7) (92.0) (83.5) (75.0) (69.4) (64.6)
4 4.026 23000 15800 12800 10900 9700 8800 8100 7500 7200 6700 6000 5500 5000 4600
(651) (447) (362) (309) (275) (249) (229) (212) (204) (190) (170) (156) (142) (130)
GAS SUPPLY PIPING
Table 3 - Gas Pipe Size
1. Determine the required Cu. Ft. / Hr. by dividing the rated heater input by 1000. For SI / Metric measurements: Convert unit Btu. / Hr. to
kilowatts. Multiply the units input (kW) by 0.0965 to determine Cubic Meters / Hour. 2. FOR NATURAL GAS: Select the pipe size directly
from the table. 3. FOR PROPANE GAS: Multiply the Cu. Ft. / Hr. (Cubic Meters per Hour) value by 0.633; then use the table. 4. Refer to
the metric conversion factors listed in General Safety section for more SI unit measurements/conversions.
To avoid equipment damage or possible personal injury, do not connect gas piping to
this unit until a supply line pressure/leak test has been completed. Connecting the unit before
completing the pressure/leak test may damage the unit gas valve and result in a fi re hazard.
Do not rely on a shut off valve to isolate the unit while conducting gas pressure/leak tests. These
valves may not be completely shut off, exposing the unit gas valve to excessive pressure and damage.
NOTICE: If more than one gas unit heater is to be
served by the same piping arrangement, the total
cubic feet per hour input and length of pipe must be
considered.
NOTICE: If the gas unit heater is to be fi red with LP
gas, consult the local LP gas dealer for pipe size
information.
HEATER INSTALLATION FOR USE WITH PROPANE
(BOTTLED) GAS MUST BE MADE BY A QUALIFIED
L.P. GAS DEALER OR INSTALLER. HE WILL INSURE
THAT PROPER JOINT COMPOUNDS ARE USED
FOR MAKING PIPE CONNECTIONS; THAT AIR
IS PURGED FROM LINES; THAT A THOROUGH
TEST IS MADE FOR LEAKS BEFORE OPERATING
HEATER; AND THAT IT IS PROPERLY CONNECTED
TO PROPANE GAS SUPPLY SYSTEM.
Before any connection is made to an existing line
supplying other gas appliances, contact the local gas
company to make certain that the existing line is of
adequate size to handle the combined load.
PIPE SIZING
To provide adequate gas pressure at the gas unit
heater, size the gas piping as follows:
1. Find the cu ft/hr by using the following formula:
Input
Cu. ft/hr =
Btu per Cu. ft.
2. Refer to Table 3. Match “Pipe Run in Feet” with
appropriate “Gas Input - Cu Ft/Hr” fi gure. This fi gure
can then be matched to the pipe size at the end of
the column.
Example: It is determined that a 67 foot (20.4m) run of
gas pipe is required to connect a 200 MBTU gas unit
heater to a 1,000 Btu/cu. ft (0.29 kW) natural gas supply.
200,000 Btu/hr
= 200 Cu ft/hr
1,000 Btu/cu ft
Using Table 3, a 1 inch pipe is needed.
NOTICE: See General Safety Information section for
English/SI (metric) unit conversion factors.