
Parker Hannifin Corporation
Parflex Division
Ravenna, Ohio
Bulletin No. 4660-PGP2T
Parflex
®
Flexible Gas Piping System
Design and Installation Guide
3.2.8 Elevated Dual Pressure System - Propane
This a 2 psig supply pressure parallel arrange-
ment. This system is similar to the natural gas
elevated dual pressure system except that the
fuel gas is propane and the run from the meter
to the reducing regulator is a long distance (200
ft.). The pressure downstream of the meter is 2
psig and the maximum pressure drop from the
meter to the reducing regulator is 1.0 psig. The
outlet pressure from the reducing regulator is
set at 11.0 inches WC. A 0.5 inch WC pressure
drop is used in sizing the tubing from the outlet
of the reducing regulator to each appliance. The
specific gravity of the gas is 1.52 and the energy
content is 1 CFH = 2,500 BTUH.
1. Total Load and Regulator Size— Calculate
the total appliance load and determine if one
regulator has sufficient capacity. The total
load is 73.6 CFH (184,000 BTUH). The supply
pressure from the meter/ primary regula-
tor is 2 psig and the pressure drop from the
meter to the reducing regulator is 1.0 psig;
therefore, the inlet pressure to the reducing
regulator is 1.0 psig. Since the outlet pres-
sure of the reducing regulator is set at 11.0
inches WC, the expected pressure drop across the regulator is 17 inches WC (1.0 psig - 11.0” WC = 17”
WC). A single 325-3 line regulator has a flow rate capacity of 225 CFH for natural gas. This value must,
however, be converted to a flow rate for propane with a specific gravity of 1.52. Using the specific grav-
ity conversion factor table at the sizing tables, we find that a multiplier is not shown for propane having
a specific gravity of 1.52. Using the next higher gravity value of 1.60, we find that the multiplier is 0.61.
Multiplying this value by the natural gas flow rate of 225 CFH, we obtain 137 CFH (225 CFH x 0.61). The
325-3 regulator has a propane flow capacity which exceeds the system requirement of 73.6 CFH.
2. Sizing Section A (First Stage Regulator)—Section A must have capacity to supply all appliances through
the reducing regulator. The total load is 73.6 CFH (184,000 BTUH) and the distance is 200 ft. Referring
to Table 14 (meter to regulator with 2 psig inlet and 1.0 psig drop) under the 200 ft. length column, we
find that size ½ inch (PGP-8) has capacity above 184,000 BTUH (225,000). Use 1/2 inch (PGP-8) to run
Section A. To size the remaining sections, the pressure source is the outlet of the reducing pressure
regulator rather than the meter. Use the low-pressure Table 12 (11.0 inch WC inlet with 0.5 inch WC
drop) for propane. Size each section individually using the appliance load and run distance.
3. Sizing Section B—Section B supplies the oven/range. The load is 50,000 BTUH and the distance be-
tween the regulator outlet and the appliance is 20 ft. The total pressure drop from the regulator outlet
to the appliance is 0.5 inch WC and the regulator output pressure is set at 11.0 inches WC. Referring to
Table 12 under the 20 ft. length column, we find that 1/2 inch (PGP-8) has capacity above 50,000 BTUH
(106,000 BTUH). Use 1/2 inch (PGP-8) to run Section B.
4. Sizing Section C—Section C supplies the furnace with a load of 75,000 BTUH over a distance of 5 ft. Re-
ferring to Table 12 under the 5 ft. length column, we find that size 3/8 inch (PGP-6) has capacity above
75,000 BTUH (82,000). Use 3/8 inch (PGP-6) to run Section C.
5. Sizing Section D—Section D supplies the dryer with a load of 25,000 BTUH over a distance of 35 ft. Re-
ferring to Table 12, a 35 ft. length column does not exist. Use the 40 ft. length column and find that size
3/8 inch (PGP-6) has capacity above 25,000 BTUH (29,000). Use 3/8 inch (PGP-6) to run Section D.
6. Sizing Section E—Section E supplies the water heater with a load of 34,000 BTUH over a distance of 50
ft. Referring to Table 12 under the 50 ft. length column. We find that size 1/2 inch (PGP-8) has capacity
above 34,000 BTUH (70,000). Use 1/2 inch (PGP-8) to run Section E.
Applince Loads
Lemgths
Table Size
Meter To Regulator
A = 200 ft.
PGP-8 (1/2")
Oven/range = 20CFH (50,000 BTUH/2500)
B = 20 ft.
PGP-8 (1/2")
Furnace = 30 CFH (75,000 BTUH/2500)
C = 5 ft.
PGP-6 (3/8")
Dryer = 10 CFH (25,000 BTUH/2500)
D = 35 ft.
PGP-6 (3/8")
Water Heater = 13.6 CFH (34,000 BTUH/2500)
E = 50 ft.
PGP-8 (1/2")
Elevated Dual Pressure Propane System
Section 3.0 System Configuration & Sizing