Guide to Orifice Flow Capacities Caution: Orifice flow capacities are dependant on a variety of factors that cannot be included in a simple table. Capacities vary with the composition of the gas, specific gravity, orifice configuration, back pressure etc. This data is approximate.
Natural Gas LPG
MJ/hr BTU/hr MJ/hr BTU/hr
DRILL SIZE at at at at
mm MTD 1 kPa 4" WG 2.75 kPa 11" WG
0.32 0.44 414
0.35 80 0.52 495 1.34 1273
0.38 79 0.60 571 1.54 1469
0.40 78 0.73 695 1.88 1788
0.45 77 0.93 879 2.37 2263
0.50 76 1.15 1086 2.93 2794
0.52 75 1.25 1197 3.24 3081
0.58 74 1.45 1374 3.73 3536
0.60 73 1.65 1563 4.25 4024
0.65 72 1.79 1696 4.60 4366
0.68 71 1.94 1835 5.00 4722
0.70 70 2.24 2128 5.77 5476
0.75 69 2.44 2314 6.30 5956
0.80 68 2.75 2608 7.08 6713
0.82 67 2.93 2779 7.55 7153
0.85 66 3.11 2956 8.03 7607
0.90 65 3.55 3325 9.03 8557
0.92 64 3.71 3518 9.55 9053
0.95 63 3.91 3716 10.09 9563
0.98 62 4.11 3919 10.64 10087
1.00 61 4.34 4128 11.21 10625
1.02 60 4.60 4343 11.80 11176
1.05 59 4.80 4563 12.40 11742
1.07 58 5.04 4788 13.00 12322
1.10 57 5.30 5019 13.66 12916
1.20 56 6.20 5869 15.93 15104
1.30 55 7.74 7339 19.93 18888
1.40 54 8.66 8211 22.30 21131
1.50 53 10.10 9609 26.10 24730
1.60 52 11.51 10945 29.72 28167
1.70 51 12.85 12184 33.00 31357
1.80 50 14.01 13300 36.00 34228
1.85 49 15.25 14464 39.27 37225
1.95 48 16.54 15678 42.57 40347
2.00 47 17.64 16726 45.41 43045
2.05 46 18.79 17809 48.35 45831
2.10 45 19.25 18251 49.55 46969
2.20 44 21.18 20075 54.50 51663
2.25 43 22.68 21500 58.37 55331
2.35 42 25.03 23729 64.43 61067
2.45 41 26.39 25015 67.92 64377
2.50 40 27.50 26068 70.78 67087
2.55 39 28.35 26872 72.96 69157
2.60 38 29.50 27963 75.92 71964
2.65 37 31.00 29358 79.71 75553
2.70 36 32.48 30786 83.59 79229
2.75 35 34.65 32843 89.17 84522
2.80 34 35.28 33443 90.80 86066
2.85 33 36.57 34659 94.10 89195
2.95 32 38.53 36524 99.16 93994
3.00 31 41.24 39086 106.12 100589
3.30 30 47.28 44819 121.69 115343
3.50 29 53.00 50204 136.31 129200
3.55 28 56.53 53581 145.48 137892
3.60 27 59.38 56284 152.81 144847
3.70 26 61.88 58653 159.25 150945
3.80 25 64.00 60665 164.71 156123
3.85 24 66.16 62711 170.27 161389
3.90 23 67.91 64372 174.78 165664
3.95 22 70.58 66905 181.65 172181
4.00 21 72.40 68620 186.31 176596
4.10 20 74.23 70357 191.03 181066
4.20 19 78.91 74795 203.00 192487
4.30 18 82.27 77982 211.73 200690
4.40 17 85.70
