1310.2.1 Mains and Branches

Mains and branches in medical gas piping systems shall be not less than DN15 (NPS ¹/₂) (⁵/₈ inch O.D.) size. Mains and branches in medical-surgical vacuum systems shall be not less than DN20 (NPS ³/₄) (⁷/₈ inch O.D.) size. [NFPA 99:5.1.10.11.1.2, 5.1.10.11.1.3]

TABLE 1310.2.1(1)
SYSTEM SIZING — FLOW REQUIREMENTS FOR STATION OUTLETS AND INLETS¹

NUMBER OF OUTLETS AND INLETS TERMINAL UNITS PER FACILITY	DIVERSITY PERCENTAGE OF AVERAGE FLOW PER OUTLETS AND INLETS TERMINAL UNITS	MINIMUM PERMISSIBLE SYSTEM FLOW OF ALL PRESSURIZED MEDICAL GAS SYSTEMS2 (standard cubic feet per minute)
1—10	100%	Actual Demand
11—25	75%	7.0
26—50	50%	13.1
51—100	50%	17.5

Notes:

¹ Flow rates of station outlets and inlets in accordance with Table 1305.2.

² The minimum system flow is the average outlets and inlets flow times the number of station outlets and inlets times the diversity percentage.

TABLE 1310.2.1(2)
PRESSURE LOSS FOR MEDICAL AIR

FLOW RATE (SCFM)1	PRESSURE DROP (psi) PER 100 FEET2
	1/2 INCH PIPE	3/4 INCH PIPE	1 INCH PIPE
0.35	0.004	0.001	—
0.71	0.012	0.003	—
1.06	0.023	0.005	—
1.41	0.037	0.007	—
1.77	0.055	0.011	—
2.12	0.075	0.015	—
2.47	0.097	0.019	—
2.82	0.123	0.024	—
3.18	0.151	0.029	—
3.53	0.181	0.035	—
4.24	0.249	0.048	—
4.94	0.326	0.063	—
5.65	0.413	0.080	—
6.36	0.507	0.098	—
7.06	0.611	0.118	0.030
7.77	0.723	0.139	0.035
8.47	0.843	0.162	0.041
9.18	0.969	0.187	0.047
9.89	1.108	0.212	0.053
10.59	1.252	0.240	0.060
12.36	1.647	0.315	0.079
14.12	2.090	0.398	0.100
15.89	2.580	0.490	0.123
17.66	3.116	0.591	0.148
19.42	—	0.701	0.176
21.19	—	0.818	0.205
22.95	—	0.944	0.236
24.72	—	1.078	0.268
28.25	—	1.369	0.341
31.78	—	1.690	0.421
35.31	—	2.043	0.509
38.84	—	2.425	0.603
42.37	—	2.838	0.705
45.90	—	3.280	0.814
49.43	—	3.751	0.929
52.97	—	4.249	1.052
56.50	—	—	1.181
60.03	—	—	1.318
63.56	—	—	1.461
67.09	—	—	1.611
70.62	—	—	1.768
81.21	—	—	2.276
88.28	—	—	2.647
95.34	—	—	3.044

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, I pound-force per square inch = 6.8947 kPa

Notes:

¹ Based on the pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on the pressure of 55 psig (379 kPa) at 68°F (20°C).

TABLE 1310.2.1(3) PRESSURE LOSS FOR NITROGEN

FLOW RATE (SCFM)1	PRESSURE DROP (psi) PER 100 FEET2
	1/2 INCH PIPE	3/4 INCH PIPE	1 INCH PIPE
5.30	0.126	0.024	—
10.59	0.430	0.082	—
15.89	0.886	0.168	—
21.19	1.485	0.281	—
26.48	2.220	0.419	—
31.78	3.089	0.581	—
37.08	4.087	0.766	—
42.37	—	0.975	—
47.67	—	1.206	—
52.97	—	1.460	0.361
58.26	—	1.736	0.429
63.56	—	2.033	0.502
68.85	—	2.352	0.580
74.15	—	2.692	0.663
79.45	—	3.054	0.752
84.74	—	3.436	0.845
90.04	—	3.840	0.943
95.34	—	4.264	1.046
100.63	—	4.709	1.154
105.93	—	—	1.267
116.52	—	—	1.508
127.12	—	—	1.768
137.71	—	—	2.046
148.30	—	—	2.344
158.90	—	—	2.660
169.49	—	—	2.994
180.08	—	—	3.347
190.67	—	—	3.719
201.27	—	—	4.108
211.86	—	—	4.516
222.45	—	—	4.942
233.05	—	—	—
243.64	—	—	—
254.23	—	—	—
264.83	—	—	—
275.42	—	—	—
286.01	—	—	—
296.60	—	—	—
307.20	—	—	—
317.79	—	—	—

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

Notes:

¹ Based on the pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on the pressure of 55 psig (379 kPa) at 68°F (20°C).

TABLE 1310.2.1(4)
PRESSURE LOSS FOR NITROUS OXIDE AND CARBON DIOXIDE

FLOW RATE (SCFM)1	PRESSURE DROP (psi) PER 100 FEET2
	1/2 INCH PIPE	3/4 INCH PIPE	1 INCH PIPE
0.35	0.004	—	—
0.71	0.014	—	—
1.06	0.029	—	—
1.41	0.047	—	—
1.77	0.070	—	—
2.12	0.096	—	—
2.47	0.125	—	—
2.82	0.159	—	—
3.18	0.195	—	—
3.53	0.235	0.045	—
4.24	0.324	0.062	—
4.94	0.425	0.081	—
5.65	0.539	0.103	—
6.36	0.664	0.127	—
7.06	0.802	0.153	0.038
7.77	0.950	0.181	0.045
8.47	1.110	0.211	0.053
9.18	1.281	0.243	0.061
9.89	1.463	0.278	0.070
10.59	1.656	0.314	0.079
12.36	2.186	0.413	0.103
14.12	2.752	0.525	0.131
15.89	3.442	0.648	0.162
17.66	4.166	0.783	0.195
19.42	—	0.929	0.231
21.19	—	0.744	0.270
22.95	—	0.858	0.312
24.72	—	0.980	0.356
28.25	—	1.244	0.453
31.78	—	1.537	0.560
35.31	—	1.858	0.677
38.84	—	2.205	0.804
42.37	—	2.581	0.941
45.90	—	2.982	1.088
49.43	—	3.411	1.245
52.97	—	4.249	1.411
56.50	—	—	1.587
60.03	—	—	1.772
63.56	—	—	1.967
67.09	—	—	2.174
70.62	—	—	2.385
79.45	—	—	2.959
88.28	—	—	3.589

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

Notes:

¹ Based on the pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on the pressure of 55 psig (379 kPa) at 68°F (20°C).

TABLE 1310.2.1(5)
PRESSURE LOSS FOR OXYGEN

FLOW RATE (SCFM)1	PRESSURE DROP (psi) PER 100 FEET2
	1/2 INCH PIPE	3/4 INCH PIPE	1 INCH PIPE
0.35	0.004	—	—
0.71	0.013	0.003	—
1.06	0.025	0.005	—
1.41	0.041	0.008	—
1.77	0.060	0.012	—
2.12	0.082	0.016	—
2.47	0.107	0.021	—
2.82	0.135	0.026	—
3.18	0.166	0.032	—
3.53	0.199	0.038	—
4.24	0.274	0.053	—
4.94	0.359	0.069	—
5.65	0.454	0.087	—
6.36	0.558	0.107	—
7.06	0.672	0.129	0.033
7.77	0.795	0.153	0.039
8.47	0.927	0.179	0.045
9.18	1.066	0.205	0.052
9.89	1.218	0.233	0.059
10.59	1.377	0.263	0.066
12.36	1.811	0.346	0.087
14.12	2.298	0.438	0.110
15.89	2.837	0.539	0.135
17.66	3.456	0.650	0.163
19.42	—	0.771	0.193
21.19	—	0.900	0.225
22.95	—	1.038	0.260
24.72	—	1.185	0.295
28.25	—	1.505	0.375
31.78	—	1.859	0.463
35.31	—	2.247	0.559
38.84	—	2.667	0.663
42.37	—	3.121	0.775
45.90	—	3.607	0.895
49.43	—	4.125	1.022
52.97	—	—	1.157
56.50	—	—	1.299
60.03	—	—	1.449
63.56	—	—	1.607
67.09	—	—	1.772
70.62	—	—	1.944
81.21	—	—	2.503
91.81	—	—	3.127
102.40	—	—	3.813

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

Notes:

¹ Based on pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on pressure of 55 psig (379 kPa) at 68°F (20 °C).

TABLE 1310.2.1(6)
PRESSURE LOSS FOR VACUUM

FLOW RATE (SCFM)1	VACUUM LOSS (inch of mercury) PER 100 FEET FOR COPPER TUBE2
	3/4 INCH TUBE	1 INCH TUBE	11/4 INCH TUBE	11/2 INCH TUBE	2 INCH TUBE
0.35	0.019	—	—	—	—
0.71	0.061	—	—	—	—
1.06	0.120	—	—	—	—
1.41	0.194	—	—	—	—
1.77	0.284	—	—	—	—
2.12	0.387	—	—	—	—
2.47	0.504 —	—	—	—
2.82	0.634	—	—	—	—
3.18	0.777	—	—	—	—
3.53	0.932	0.238	—	—	—
4.24	1.277	0.325	—	—	—
4.94	1.669	0.424	—	—	—
5.65	2.106	0.534	—	—	—
6.36	2.586	0.655	—	—	—
7.06	3.110	0.787	0.272	—	—
7.77	3.674	0.929	0.321	—	—
8.47	4.280	1.081	0.373	—	—
9.18	4.927	1.243	0.429	—	—
9.89	—	1.416	0.488	—	—
10.59	—	1.597	0.551	0.242	—
11.30	—	1.789	0.616	0.270	—
12.01	—	1.990	0.685	0.300	—
12.71	—	2.200	0.757	0.332	—
13.42	—	2.419	0.832	0.365	—
14.12	—	2.648	0.911	0.399	—
14.83	—	2.886	0.992	0.435	—
15.54	—	3.132	1.077	0.471	—
16.24	—	3.388	1.164	0.510	—
16.95	—	3.652	1.254	0.549	—
17.66	—	3.925	1.348	0.590	—
18.36	—	4.207	1.444	0.632	0.167
19.07	—	4.498	1.543	0.675	0.179
19.77	—	4.797	1.646	0.720	0.190
20.48	—	—	1.751	0.766	0.202
21.19	—	—	1.859	0.813	0.214
24.72	—	—	2.441	1.066	0.281
28.25	—	—	3.092	1.350	0.356
31.78	—	—	3.811	1.662	0.438
35.31	—	—	4.596	2.004	0.527
38.84	—	—	—	2.373	0.624
42.37	—	—	—	2.770	0.728
45.90	—	—	—	3.194	0.838
49.43	—	—	—	3.645	0.956
52.97	—	—	—	4.122	1.081
56.50	—	—	—	4.626	1.212
63.56	—	—	—	—	1.495
70.62	—	—	—	—	1.803
77.68	—	—	—	—	2.138
84.74	—	—	—	—	2.497
91.81	—	—	—	—	2.882
98.87	—	—	—	—	3.291
105.93	—	—	—	—	3.724
112.99	—	—	—	—	4.181

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, 1 inch of mercury = 3.386 kPa

Notes:

¹ Based on the pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on the pressure of 19 inches of mercury gauge vacuum (64 kPa) at 68°F (20°C).

TABLE 1310.2.1(7)
PRESSURE LOSS FOR VACUUM (CATEGORY 3)

FLOW RATE (SCFM)1	VACUUM LOSS (inch of mercury) PER 100 FEET FOR COPPER TUBE2
	3/4 INCH TUBE	1 INCH TUBE	11/4 INCH TUBE	11/2 INCH TUBE	2 INCH TUBE
0.35	0.005	—	—	—	—
0.71	0.010	—	—	—	—
1.06	0.015	—	—	—	—
1.41	0.021	—	—	—	—
1.77	0.026	—	—	—	—
2.12	0.060	0.010	—	—	—
2.47	0.077	0.020	—	—	—
2.82	0.096	0.025	—	—	—
3.18	0.118	0.031	0.011	—	—
3.53	0.141	0.036	0.013	—	—
4.24	0.192	0.050	0.017	—	—
4.94	0.249	0.064	0.023	0.010	—
5.65	0.313	0.081	0.028	0.012	—
6.36	0.383	0.099	0.035	0.015	—
7.06	0.459	0.118	0.041	0.018	—
7.77	0.541	0.139	0.049	0.021	—
8.47	0.628	0.161	0.056	0.024	—
9.18	0.722	0.185	0.065	0.027	—
9.89	0.821	0.210	0.073	0.031	—
10.59	0.925	0.237	0.083	0.035	—
11.30	1.035	0.265	0.092	0.039	0.010
12.01	1.151	0.294	0.102	0.043	0.011
12.71	1.270	0.324	0.113	0.048	0.012
13.42	1.396	0.356	0.124	0.052	0.014
14.12	1.525	0.389	0.135	0.057	0.015
14.83	1.662	0.424	0.147	0.062	0.016
15.54	1.803	0.460	0.160	0.068	0.017
16.24	1.948	0.496	0.172	0.073	0.019
16.95	2.099	0.535	0.186	0.078	0.020
17.66	2.256	0.574	0.199	0.084	0.022
18.36	2.415	0.615	0.213	0.090	0.023
19.07	2.581	0.657	0.228	0.096	0.025
19.77	2.750	0.699	0.243	0.102	0.026
20.48	2.925	0.744	0.258	0.109	0.028
21.19	3.106	0.790	0.274	0.115	0.030
24.72	4.074	1.034	0.358	0.151	0.039
28.25	—	1.307	0.452	0.190	0.049
31.78	—	1.608	0.556	0.234	0.060
35.31	—	1.936	0.669	0.281	0.072
38.84	—	2.291	0.791	0.332	0.085
42.37	—	2.672	0.922	0.387	0.099
45.90	—	3.078	1.062	0.446	0.113
49.43	—	3.510	1.211	0.508	0.129
52.97	—	3.969	1.368	0.574	0.146
56.50	—	4.450	1.534	0.643	0.163
63.56	—	—	1.890	0.792	0.201
70.62	—	—	2.278	0.954	0.242
77.68	—	—	2.699	1.130	0.286
84.74	—	—	3.151	1.318	0.334
91.81	—	—	3.634	1.520	0.385
98.87	—	—	4.148	1.734	0.439
105.93	—	—	4.691	1.961	0.496
112.99	—	—	—	2.200	0.556

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25mm, 1 foot = 304.8 mm, 1 inch of mercury = 3.386 kPa

Notes:

¹ Based on the pressure of 14.7 psig (101 kPa) at 68°F (20°C).

² Based on the pressure of 19 inches of mercury gauge vacuum (64 kPa) at 68°F (20°C).