Natural Gas and Propane Line Sizing

Proper sizing of fuel gas pipes is critical to the proper operation of equipment, following all local gas bylaws and codes.

In Canada CSA 149.1 specification should be followed. Regional jurisdictions may differ; consult local licensed gas fitters and professionals. Eco Power Equipment typically recommends following CSA 149.1, other standards may be pertinent.

Step by Step:

Determine the total developed length of pipe from the Gas Regulator to the farthest the appliance connection.
Count all fittings (90 degrees, 45 degrees, Tees, etc)
Select a delivery pressure and determine the allowable pressure drop. (0.3 - 0.5 in WC for low pressure. Up to 10% for medium pressure is recommended)
Calculate the total BTU/HR required by the equipment

Gas Layout

Once you calculate the length of straight pipe sections within the system, you can use the following chart for length equivalents for fittings by size.

Resistance of bends, fittings, and valves for natural gas and propane expressed in equivalent length of straight pipe in feet* (See Clauses 6.3.7, A.2.4, and A.4 of CSA 149.1 Code Book)
Nominal Pipe Size	Inside Diameter	45°	90°	TEE
3/8	0.493	0.58	1.23	2.46
1/2	0.622	0.73	1.55	3.1
3/4	0.824	0.96	2.06	4.12
1	1.049	1.22	2.62	5.24
1-1/4	1.38	1.61	3.45	6.9
1-1/2	1.61	1.88	4.02	8.04
2	2.067	2.41	5.17	10.3
2-1/2	2.469	2.88	6.16	12.3
3	3.068	3.58	7.67	15.3

For example - a 1" 90-degree fitting equals 2.62 feet of pipe.

The next step is to review your site pressure conditions for your supply side; here are some typical supply pressures by fuel pressure.

Natural Gas:

CHART H - 2PSI NATURAL GAS SYSTEM
Maximum capacity of natural gas in thousands of Btu/h for Schedule 40 pipe and plastic pipe for pressures of 5 psig based on a pressure drop of 2.5 psig. (See Clauses A.2.3, A.2.4, A.2.6, and A.3.5. of CSA 149.1 Code Book)
Length of pipe,ft	1/2	3/4	1	1-1/4	1-1/2	2
10	1440	3012	5673	11648	17425	33610
20	990	2070	3899	8005	11994	23100
30	795	1662	3131	6429	9632	18550
40	680	1423	2680	5502	8244	15877
50	603	1261	2375	4876	7306	14071
60	546	1142	2152	4418	6620	12749
70	503	1051	1980	4065	6090	11729
80	468	978	1842	3782	5666	10912
90	439	917	1728	3548	5316	10238
100	414	867	1632	3351	5022	9671
125	367	768	1447	2970	4451	8571
150	333	696	1311	2691	4032	7766
175	306	640	1206	2476	3710	7145
200	285	596	1122	2303	3451	6647

CHART I- 5PSI NATURAL GAS SYSTEM
Maximum capacity of natural gas in thousands of Btu/h for Schedule 40 pipe and plastic pipe for pressures of 5 psig based on a pressure drop of 2.5 psig. (See Clauses A.2.3, A.2.4, A.2.6, and A.3.5. of CSA 149.1 Code Book)
Length of pipe,ft	1/2	3/4	1	1-1/4	1-1/2	2
10	2800	5855	11028	22643	33925	65337
20	1924	4024	7580	15562	23317	44906
30	1545	3231	6087	12497	18724	36061
40	1323	2766	5210	10696	16026	30864
50	1172	2451	4617	9479	14203	27354
60	1062	2221	4183	8589	12869	24785
70	977	2043	3849	7902	11839	22801
80	909	1901	3581	7351	11014	21212
90	853	1783	3359	6897	10334	19903
100	806	1685	3173	6515	9762	18800
125	714	1493	2812	5774	8652	16662
150	647	1353	2548	5232	7839	15097
175	595	1245	2344	4813	7212	13889
200	554	1158	2181	4478	6709	12921

Propane:

CHART K - 10PSI PROPANE GAS SYSTEM
Maximum capacity of propane in thousands of Btu/h for Schedule 40 pipe and plastic pipe for pressures of 10 psig based on a pressure drop of 5 psig (See Clauses 6.3.5, 8.2.3, 8.2.4, and 8.3.5 of CSA 149.1 Code Book)
Length of pipe,ft	1/2	3/4	1	1-1/4	1-1/2	2
10	7658	16014	30166	61933	92795	178714
20	5264	11006	20733	42566	63777	122829
30	4227	8838	16649	34182	51216	98636
40	3618	7565	14249	29256	48834	84420
50	3206	6704	12629	25929	38949	74820
60	2905	6075	11443	23493	35200	67792
70	2673	5589	10527	21613	32384	62368
80	2486	5199	9794	20107	30127	58021
90	2333	4878	9189	18866	28267	54439
100	2204	4608	8680	17821	26701	51423
125	1953	4084	7693	15794	23664	45575
150	1770	3700	6970	14311	21442	41295
175	1628	3404	6413	13166	19726	37990
200	1515	3167	5966	12248	18351	35343

On the secondary side, which is typically low pressure, here are some common pressures.

CHART J - 11” WC PROPANE GAS SYSTEM
Maximum capacity of propane in thousands of Btu/h for Schedule 40 pipe and plastic pipe, including fittings, for pressures of 11 in w.c. based on a pressure drop of 1 in w.c. (See Clauses 6.3.2, 6.3.5, B.2.3, B.2.4, and B.3.5 of CSA 149.1 Code Book)
Length of pipe,ft	1/2	3/4	1	1-1/4	1-1/2	2	2-1/2	3
10	386	807	1520	3121	4676	9005	14353	25374
20	265	555	1045	2145	3214	6189	9865	17439
30	213	445	839	1722	2581	4970	7922	14004
40	182	381	718	1474	2209	4254	6780	11986
50	162	338	636	1307	1958	3770	6009	10623
60	146	306	577	1184	1774	3416	5445	9625
70	135	282	530	1089	1632	3143	5009	8855
80	125	262	493	1013	1518	2924	4660	8238
90	118	246	463	951	1424	2743	4372	7729
100	111	232	437	898	1345	2591	4130	7301
125	98	206	388	796	1192	2297	3660	6471
150	89	186	351	721	1080	2081	3317	5863
175	82	172	323	663	994	1914	3051	5394
200	76	160	301	617	925	1781	2839	5018

CHART G - 7” WC NATURAL GAS SYSTEM
Maximum capacity of natural gas in thousands of Btu/h for Schedule 40 pipe and plastic pipe, including fittings, for pressures of less than 7 in w.c. based on a pressure drop of 0.5in w.c. (See Clauses 6.3.2, A.2.3, A.2.4, A.2.6, and A.3.5 of CSA 149.1 Code Book)
Length of pipe,ft	1/2	3/4	1	1-1/4	1-1/2	2	2-1/2	3
10	156	326	614	1261	1890	3639	5800	10253
20	107	224	422	867	1299	2501	3986	7047
30	86	180	339	696	1043	2008	3201	5659
40	74	154	290	596	893	1719	2740	4843
50	65	137	257	528	791	1524	2428	4293
60	59	124	233	478	717	1380	2200	3889
70	54	114	214	440	659	1270	2024	3578
80	51	106	199	409	613	1181	1883	3329
90	48	99	187	384	576	1109	1767	3123
100	45	94	177	363	544	1047	1669	2950
125	40	83	157	322	482	928	1479	2615
150	36	75	142	291	437	841	1340	2369
175	33	69	131	268	402	774	1233	2180
200	31	64	121	249	374	720	1147	2028