Appliance Gas Pipe Flow Rate Capacities

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Appliance Gas Pipe Flow Rate Capacities

HVAC Systems and Components
Fluids Engineering and Design

Appliance Natural Gas Pipe Flow Rate Capacities

Also see: Natural Gas Pipe Flow Rate Requirement Formulas and Calculator for pressure less than 1.5 psig

Piping for natural gas appliances should be of adequate size and installed so that it provides a supply of gas sufficient to meet the maximum demand without undue loss of pressure between the point of supply (the meter) and the appliance. The size of gas pipe required depends on:

(1) maximum gas consumption to be provided,
(2) length of pipe and number of fittings,
(3) allowable pressure loss from the outlet of the meter to the appliance,
(4) specific gravity of the gas.

Gas consumption in ft³/h is obtained by dividing the Btu input rate at which the appliance is operated by the average heating value of the gas in Btu/ft³. Insufficient gas flow in gas supply lines can cause inefficient operation of gas-fired appliances and sometimes create hazardous operations. Gas-fired appliances are normally equipped with a data plate giving information on maximum and/or minimum gas flow requirements or Btu input as well as inlet gas pressure requirements. The local gas utility can give the gas pressure available at the utility’s gas meter. Using this information, the required size of gas piping can be calculated for satisfactory operation of the appliance(s).

The data table given below provides recommended pipe capacities for gas flow for up to 200 ft of pipe based on a specific gravity of 0.60.

Maximum Capacity of Gas Pipe in Cubic Feet per Hour for pipe lengths 10 to 80 ft.

Nominal Iron Pipe Size, in.	Internal Diameter, in.	Length of Pipe, ft
Nominal Iron Pipe Size, in.	Internal Diameter, in.	10	20	30	40	50	60	70	80
1/4	0.364	32	22	18	15	14	12	11	11
3/8	0.493	72	49	40	34	30	27	25	23
1/2	0.622	132	92	73	63	56	50	46	43
3/4	0.824	278	190	152	130	115	105	96	90
1	1.049	520	350	285	245	215	195	180	170
1-1/4	1.380	1,050	730	590	500	440	400	370	350
1-1/2	1.610	1,600	1,100	890	760	670	610	560	530
2	2.067	3,050	2,100	1,650	1,450	1,270	1,150	1,050	990
2-1/2	2.469	4,800	3,300	2,700	2,300	2,000	1,850	1,700	1,600
3	3.068	8,500	5,900	4,700	4,100	3,600	3,250	3,000	2,800
4	4.026	17,500	12,000	9,700	8,300	7,400	6,800	6,200	5,800

Maximum Capacity of Gas Pipe in Cubic Feet per Hour for pipe lengths 90 to 200 ft.

Nominal Iron Pipe Size, in.	Internal Diameter, in.	Length of Pipe, ft
Nominal Iron Pipe Size, in.	Internal Diameter, in.	90	100	125	150	175	200
1/4	0.364	10	9	8	8	7	6
3/8	0.493	22	21	18	17	15	14
1/2	0.622	40	38	34	31	28	26
3/4	0.824	84	79	72	64	59	55
1	1.049	160	150	130	120	110	100
1-1/4	1.380	320	305	275	250	225	210
1-1/2	1.610	490	460	410	380	350	320
2	2.067	930	870	780	710	650	610
2-1/2	2.469	1,500	1,400	1,250	1,130	1,050	980
3	3.068	2,600	2,500	2,200	2,000	1,850	1,700
4	4.026	5,400	5,100	4,500	4,100	3,800	3,500

Note: Capacity is in cubic feet per hour at gas pressures of 0.5 psig or less and pressure drop of 0.3 in. of water; specific gravity = 0.60.

References:

American Gas Association and National Fire Protection Association.