NFPA 54 - Annex F - Flow of Gas through Fixed Orifices This annex is not a part of the requirements of this code but is included for informational purposes only. F.1 Use of Orifice Tables F.1.1 To Check Burner Input Not Using a Meter. Gauge the size of the burner orifice and determine flow rate at sea level from Table F.1, F.1, Utility Gases (cubic feet per hour), or from Table F.2, F.2, LP-Gases (Btu per hour). When the specific gravity of the utility gas is other than 0.60, select the multiplier from Table F.3 for the specific gravity of the utility gas served, and apply to the flow rate as determined from Table F.1 When the altitude is above 2,000 ft (600 m), first select equivalent orifice size at sea level using Table F.4, F.4, then determine flow rate from Table F.1 or Table F.2 as directed. Having determined flow rate (as adjusted for specific gravity and/or altitude where necessary), check the burner input at sea level with the manufacturer’s rated input. input. F.1.2 To Select Correct Orifice Size for Rated Burner Input. The selection of a fixed orifice size for any rated burner input is affected by many variables, including orifice coefficient, and it is recommended that the appliance manufacturer be consulted for that purpose. When the correct orifice size cannot be readily determined, the orifice flow rates, as stated in the tables in this annex, can be used to select a fixed orifice size with a flow rate to approximately equal the required rated burner input.
For gases of the specific gravity and pressure conditions stipulated at elevations under 2000 ft (610 m), Table F.1 (in cubic feet per hour) or Table F.2 (in Btu per hour) can be used directly. Where the specific gravity of the gas is other than 0.60, select the multiplier from Table F.3 for the utility gas served and divide the rated burner input by the selected factor to determine equivalent input at a specific gravity of 0.60; then select orifice size as directed above. Where the appliance is located at an altitude of 2000 ft (610 m) or above, first use the manufacturer’s rated input at sea level to select orifice size as directed, then use Table F.4 to select the equivalent orifice size for use at the higher altitude.
NFPA 54 - Table F.1 Utility Gases (cubic feet per hour at sea level) (Natural Gas) Orifice or Drill Size 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35
3 0.48 0.55 0.70 0.88 1.05 1.16 1.33 1.51 1.64 1.82 2.06 2.25 2.52 2.69 2.86 3.14 3.41 3.63 3.78 4.02 4.21 4.41 4.66 4.84 5.68 7.11 7.95 9.30 10.61 11.82 12.89 14.07 15.15 16.22 17.19 17.73 19.45 20.73 23.10 24.06 25.03 26.11 27.08 28.36 29.76 32.36
3.5 0.52 0.59 0.65 0.95 1.13 1.25 1.44 1.63 1.77 1.97 2.22 2.43 2.72 2.91 3.09 3.39 3.68 3.92 4.08 4.34 4.55 4.76 5.03 5.23 6.13 7.68 8.59 10.04 11.46 12.77 13.92 15.20 16.36 17.52 18.57 19.15 21.01 22.39 24.95 25.98 27.03 28.20 29.25 30.63 32.14 34.95
4 0.55 0.64 0.78 0.99 1.21 1.34 1.55 1.76 1.90 2.06 2.39 2.61 2.93 3.12 3.32 3.72 4.14 4.19 4.39 4.66 4.89 5.11 5.39 5.63 6.58 8.22 9.23 10.80 12.31 13.69 14.94 16.28 17.62 18.80 19.98 20.52 22.57 24.18 26.50 28.15 29.23 30.20 31.38 32.99 34.59 36.86
Pressure at Orifice — ( in. w.c.) 5 6 7 0.63 0.69 0.73 0.72 0.80 0.84 0.88 0.97 1.04 1.11 1.23 1.31 1.37 1.52 1.61 1.52 1.64 1.79 1.74 1.91 2.05 1.99 2.17 2.32 2.15 2.40 2.52 2.33 2.54 2.73 2.70 2.97 3.16 2.96 3.23 3.47 3.26 3.58 3.88 3.52 3.87 4.13 3.75 4.11 4.39 4.28 4.62 4.84 4.48 4.91 5.23 4.75 5.19 5.55 4.96 5.42 5.81 5.27 5.77 6.15 5.52 5.95 6.47 5.78 6.35 6.78 6.10 6.68 7.13 6.36 6.96 7.44 7.35 8.03 8.73 9.30 10.18 10.85 10.45 11.39 12.25 12.20 13.32 14.29 13.86 15.26 16.34 15.47 16.97 18.16 16.86 18.48 19.77 18.37 20.20 21.60 19.88 21.81 23.31 21.27 23.21 24.93 22.57 24.72 26.43 23.10 25.36 27.18 25.57 27.93 29.87 27.29 29.87 32.02 29.50 32.50 35.24 31.69 34.81 37.17 33.09 36.20 38.79 34.05 37.38 39.97 35.46 38.89 41.58 37.07 40.83 43.62 39.11 42.76 45.77 41.68 45.66 48.78
8 0.79 0.90 1.10 1.38 1.72 1.91 2.18 2.48 2.69 2.91 3.38 3.68 4.14 4.41 4.68 5.16 5.59 5.92 6.20 6.57 6.91 7.25 7.62 7.94 9.32 11.59 13.08 15.27 17.44 19.40 21.12 23.06 24.90 26.62 28.23 29.03 31.89 34.19 37.63 39.70 41.42 42.68 44.40 46.59 48.88 52.10
9 0.83 0.97 1.17 1.47 1.83 2.04 2.32 2.64 2.86 3.11 3.59 3.94 4.41 4.69 4.98 5.50 5.95 6.30 6.59 7.00 7.35 7.71 8.11 8.46 9.92 12.34 13.93 16.25 18.57 20.64 22.48 24.56 26.51 28.34 30.05 30.90 33.96 36.41 40.07 42.27 44.10 45.44 47.27 49.60 52.04 55.46
10 0.88 1.01 1.24 1.55 1.92 2.14 2.44 2.78 3.00 3.26 3.78 4.14 4.64 4.94 5.24 5.78 6.26 6.63 6.94 7.37 7.74 8.11 8.53 8.90 10.44 12.98 14.65 17.09 19.53 21.71 23.65 25.83 27.89 29.81 31.61 32.51 35.72 38.30 42.14 44.46 46.38 47.80 49.73 52.17 54.74 58.34
NFPA 54 - Table F.1 Utility Gases (cubic feet per hour at sea level) (Natural Gas) Orifice or Drill Size 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
3 32.45 33.41 35.46 37.82 43.40 48.45 51.78 54.47 56.73 58.87 60.81 62.10 64.89 66.51 68.22 72.20 75.53 78.54 82.19 85.20 87.10 89.92 93.90 95.94 98.30 100.99 103.89 105.93 109.15 111.08 114.75 119.25 128.48 136.35
3.5 35.05 36.08 38.30 40.85 46.87 52.33 55.92 58.83 61.27 63.58 65.67 67.07 70.08 71.83 73.68 77.98 81.57 84.82 88.77 92.02 94.40 97.11 101.41 103.62 106.16 109.07 112.20 114.40 117.88 119.97 123.93 128.79 138.76 147.26
4 37.50 38.79 40.94 43.83 50.39 56.19 59.50 63.17 65.86 68.22 70.58 72.20 75.21 77.14 79.08 83.69 87.56 91.10 95.40 98.84 100.78 104.32 108.52 111.31 114.21 117.11 120.65 123.01 126.78 128.93 133.22 137.52 148.61 158.25
Pressure at Orifice — ( in. w.c.) 5 6 7 42.44 46.52 49.75 43.83 48.03 51.46 46.52 50.82 54.26 49.64 54.36 58.01 57.05 62.09 66.72 63.61 69.62 74.45 67.00 73.50 79.50 71.55 78.32 83.59 74.57 81.65 87.24 77.14 84.67 90.36 79.83 87.56 93.47 81.65 89.39 94.55 85.10 93.25 99.60 87.35 95.63 102.29 89.49 97.99 104.75 94.76 103.89 110.67 97.50 108.52 116.03 103.14 112.81 120.33 107.98 118.18 126.78 111.74 122.48 131.07 114.21 124.44 133.22 118.18 128.93 138.60 123.56 135.37 143.97 126.02 137.52 147.20 129.25 141.82 151.50 132.58 145.05 154.71 136.44 149.33 160.08 139.23 152.56 163.31 142.88 156.83 167.51 145.79 160.08 170.82 150.41 164.36 176.18 156.26 170.78 182.64 168.64 184.79 197.66 179.33 194.63 209.48
8 53.12 54.96 57.95 61.96 71.22 79.52 84.92 89.27 93.17 96.50 99.83 100.98 106.39 109.24 111.87 118.55 123.92 128.52 135.39 139.98 142.28 148.02 153.75 157.20 161.81 165.23 170.96 174.38 178.88 182.48 188.16 195.08 211.05 223.65
9 56.55 58.62 61.70 65.97 75.86 84.66 90.39 95.04 99.19 102.74 106.28 107.49 113.24 116.29 119.10 125.82 131.93 136.82 144.15 149.03 151.47 157.58 163.69 167.36 172.26 175.91 182.00 185.68 190.46 194.22 200.25 207.66 224.74 238.16
10 59.49 61.55 64.89 69.39 79.80 89.04 95.09 99.97 104.57 108.07 111.79 113.07 119.12 122.33 125.28 132.36 138.78 143.91 151.63 156.77 159.33 165.76 172.13 176.03 181.13 185.03 191.44 195.30 200.36 204.30 210.71 218.44 235.58 250.54
For SI units: 1 Btu/hr = 0.293 W; 1 cubic ft = 0.028 cubic m; 1 ft = 0.305 m; 1 in. w.c. = 249 pa. Notes: 1. Specific Gravity = 0.60, Orifice Coefficient = 0.90 2. For utility gases of another specific gravity, select multiplier from Table F.3. For altitudes above 2,000 ft., first select the equivalent orifice size at sea level from Table F.4.
NFPA 54 Table F.2 LP-Gases (Btu per hour at sea level) Orifice or Drill Size Propane Butane 0.008 519 589 0.009 656 744 0.010 812 921 0.011 981 1112 0.012 1169 1326 80 1480 1678 79 1708 1936 78 2080 2358 77 2629 2980 76 3249 3684 75 3581 4059 74 4119 4669 73 4678 5303 72 5081 5760 71 5495 6230 70 6375 7227 69 6934 7860 68 7813 8858 67 8320 9433 66 8848 10031 65 9955 11286 64 10535 11943 63 11125 12612 62 11735 13304 61 12367 14020 60 13008 14747 59 13660 15486 58 14333 16249 57 15026 17035 56 17572 19921 55 21939 24872 54 24630 27922 53 28769 32615 52 32805 37190 51 36531 41414 50 39842 45168 49 43361 43361 48 46983 46983 47 50088 50088 46 53296 53296 45 54641 54641 44 60229 60229 43 64369 64369 42 71095 71095 41 74924 74924 40 78029 78029 39 80513 80513
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NFPA 54 Table F.2 LP-Gases (Btu per hour at sea level) Orifice or Drill Size Propane Butane 38 83721 83721 37 87860 87860 36 92207 92207 35 98312 98312 34 100175 100175 33 103797 103797 32 109385 109385 31 117043 117043 30 134119 134119 29 150366 150366 28 160301 160301 27 168580 168580 26 175617 175617 25 181619 181619 24 187828 187828 23 192796 192796 22 200350 200350 21 205525 205525 20 210699 210699 19 223945 223945 18 233466 233466
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Notes: Prop Propan ane e Buta Butane ne 1. Btu per Cubic Foot: 2516 3280 2. Specific Gravity: 1.5 2.01 3. Pressure at Orifice, i 11 11 4. Orifice Coefficient: 0.9 0.9 5. For altitudes above 2,000 ft (610 m), first select the equivalent orifice size at sea level from Table F.4.
NFPA 54 Table F.3 Multipliers for Utility Gases of Another Specific Gravity Specific Grav Gravit ity y Multip Mult ipli lier er 0.45 1.155 0.50 1.095 0.55 1.045 0.60 1.000 0.65 0.961 0.70 0.926 0.75 0.894 0.80 0.866 0.85 0.840 0.90 0.817 0.950 0.795 1.000 0.775 1.050 0.756 1.100 0.739 1.150 0.722 1.200 0.707 1.250 0.693 1.300 0.679 1.350 0.667 1.400 0.655
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NFPA 54 Table F.4 Equivalent Orifice Sizes at High Altitudes (includes 4% input reduction for each 1000 ft)
Orifice 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
2000 2 3 4 6 7 8 9 10 11 12 13 13 15 16 16 17 18 19 20 22 23 23 25 25 26 27 28 29 29 30 32 33 35 35 36 37 38 39 40 41 42 42 44 45 46 47 48 49
3000 2 3 5 7 8 9 10 11 12 13 13 14 15 16 17 18 19 19 20 22 23 24 25 26 27 28 28 29 30 31 32 34 35 36 36 38 39 40 41 42 42 43 44 45 47 47 48 49
Orifice Size Required at Other Elevations 4000 5000 6000 7000 3 3 4 5 4 5 6 7 7 8 9 10 8 9 11 12 9 10 12 13 10 11 12 13 11 12 13 14 12 13 13 15 12 13 14 16 13 14 15 16 14 15 16 17 15 16 17 17 16 17 18 18 17 18 18 19 17 18 19 20 18 19 19 20 19 20 21 22 20 21 22 23 21 22 23 25 23 24 25 26 24 25 26 27 25 26 27 27 26 27 27 28 27 27 28 28 27 28 28 29 28 28 29 29 29 29 29 30 29 30 30 30 30 30 30 31 31 31 31 32 32 33 34 35 35 35 36 36 36 36 37 38 36 37 37 38 37 37 38 39 38 39 40 41 39 40 41 42 41 41 42 42 41 42 42 43 42 42 43 43 42 43 43 44 43 43 44 44 44 45 45 46 45 46 47 47 47 47 48 48 47 48 48 49 49 49 49 50 49 50 50 50
8000 7 9 12 13 14 14 15 16 17 17 18 18 19 20 20 22 23 24 26 27 28 28 29 29 29 30 30 30 31 32 36 37 38 39 40 41 42 43 43 44 44 45 47 48 49 49 50 51
9000 8 10 10 13 14 15 16 16 17 18 18 19 19 20 21 22 23 24 26 27 28 28 29 29 29 30 30 30 31 31 33 37 38 40 40 41 42 43 43 44 44 45 46 47 48 49 50 51 51
10,000 10 12 12 15 16 17 17 18 18 19 19 20 20 22 23 24 25 26 27 28 29 29 29 30 30 30 30 31 31 32 35 38 40 41 42 42 43 43 44 44 45 46 47 48 49 50 50 51 52
NFPA 54 Table F.4 Equivalent Orifice Sizes at High Altitudes (includes 4% input reduction for each 1000 ft)
Orifice 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
2000 50 51 51 52 54 54 55 56 58 59 60 61 62 63 64 65 65 67 68 68 70 70 72 73 73 74 75 76 77 78 79 80
For SI units: 1 ft = 0.305 m
3000 50 51 52 53 54 55 55 56 59 60 61 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 76 77 78 80 0.013
Orifice Size Required at Other Elevations 4000 5000 6000 7000 8000 50 51 51 51 52 51 51 52 52 52 52 52 52 53 53 53 53 53 53 54 54 54 54 54 55 55 55 55 55 56 55 56 56 56 56 57 57 57 58 59 59 60 60 61 62 60 61 62 62 63 61 62 62 63 64 62 63 63 64 64 63 63 64 65 65 64 64 65 65 66 65 65 65 66 66 65 66 66 66 67 66 66 67 67 68 68 68 68 69 69 68 69 69 69 70 69 69 70 70 70 70 70 71 71 71 71 71 71 72 72 72 73 73 73 74 73 73 74 74 74 74 74 74 75 75 75 75 75 76 76 76 76 76 77 77 77 77 77 77 77 77 78 78 78 78 78 79 79 79 79 80 80 80 0.013 0.012 0.013 0.013 0.012 0.012 0.012
9000 52 53 53 54 55 56 56 59 63 63 64 65 66 66 67 67 68 69 70 71 72 73 74 74 75 76 77 77 78 80 0.012 0.012
10,000 52 53 54 54 55 56 57 60 63 64 65 65 66 67 68 68 69 70 70 71 72 73 74 75 76 76 77 77 78 80 0.01 0.011
