Nordyne RC 92+ Manifold Pressure in WC for Natural Gas at Various Altitudes, Above Sea Level

CAPACITY OF BLACK IRON GAS PIPE (CU. FT. PER HOUR)

FOR NATURAL GAS (SPECIFIC GRAVITY = 0.60)

NOMINAL					LENGTH OF PIPE RUN
							(feet)
BLACK IRON
PIPE DIAMETER		10	20	30		40		50	60	70	80
1/2		130	90	75		65		55	50	45	40
3/4		280	190	150		130		115	105	95	90
	1	520	350	285		245		215	195	180	170
1	1/4	1050	730	590		500		440	400	370	350
1	1/2	1600	1100	890		760		670	610	560	530

The cubic feet per hour listed in the table above must be greater than the cubic feet per hour of gas flow required by the furnace. To determine the cubic feet per hour of gas flow required by the furnace, divide the input rate of the furnace by the heating value of the gas:

Cubic Feet Per Hour Required =	Input To Furnace (Btu/hr)
	Heating Value of Gas (Btu/Cu. Ft.)

Table 7. Capacity of Black Iron Gas Pipe (cu. ft. per hour)

for Natural Gas (specific gravity = .60)

NATURAL GAS

ORIFICE SIZE

MAN. PRESSURE

(IN W.C.)

LP/PROPANE GAS

ORIFICE SIZE

MAN. PRESSURE

(IN W.C.)

ELEVATION (FEET ABOVE SEA LEVEL)

0-1,999	2,000-4,999	5,000-5,999	6,000-7,999	8,000-10,000
45	45	45	45	See
				Table 11
3.5	3.5	3.5 ‡	3.2 ‡	2.8 ‡
55	55	56	56	See
				Table 11
10.0	8.5	10.0	9.0	8.5

‡= Based on heating value from 900 to 999 BTUH. For heating values less than 900 BTUH multiply manifold pressure by 1.1 for corrected pressure. For heating values greater than 1,000 BTUH, multiply manifold pressure by 0.9 for corrected pressure.

Table 8. Manifold Pressure (in WC) for Natural Gas at Various Altitudes

Furnace Rating	Orifice Drill Size
Plate Input (Btu/h)	Nat.	LP
40,000	45	55
60,000	45	55
80,000	45	55
100,000	45	55
120,000	45	55

Table 10. Natural and LP Gas Orifice Sizes

for Elevations between zero and

4999 ft. Above Sea Level

Furnace Rating	Orifice Drill Size
Plate Input (Btu/h)	Nat.	LP
40,000	45	56
60,000	45	56
80,000	45	56
100,000	45	56
120,000	46	56

Table 11. Natural and LP gas Orifice Sizes for Elevations between 5000 and 10,000 ft.

Above Sea Level

29