Gas Hard Piping Size For Fire Pits

Gas Hard Piping Size For Fire Pits

 One of the most common questions we’re asked is ‘what size gas pipe should I use to feed my gas fire pit?’

The answer is often ‘much bigger than you may have thought’.

This is quite a complex issue, so we have tried to simplify it for you here, but please bear in mind this is for guidance purposes only.

The following refers to moving the gas from its source, i.e. your domestic metered supply or a large gas storage bottle to the location of your fire pit, which should be accomplished using hard piping. But what size pipe do you need.

A short example to emphasize how important this subject is: If you have 100,000 BTU available from your gas source for your fire pit, and the fire pit is 20 feet from the gas source, you would use a 3/4″ diameter hard pipe. If your fire pit is 100 feet from the gas source then you would need a 1″ diameter pipe. The 3/4″ pipe over 100 feet would only deliver 68,000 BTU’s! ( Natural Gas )

For a successful fire pit project there are two major issues to be addressed:

  1. The BTU rating of the burner must match the BTU rating of your available gas supply
  2. You must select the correct sized pipe to get the gas from its source to the fire pit site

The Gas Hard Piping Size For Fire Pits charts provided here are for a new gas line installations directly from the gas source. If you are connecting to an existing gas line, you must take into consideration the surplus capacity of the existing system, to ensure you will have sufficient pressure at your fire pit.

These charts are for reference only; we strongly recommend you consult with a Licensed Plumber/Gas Fitter or the NFPA54 ( National F Gas Code – current edition ) for more details.

How to use the Charts?

Using the Natural Gas Chart as an example, let’s assume you are planning to install a 75,000 BTU gas burner in your fire pit project. The column on the left represents the length of piping to reach from your gas source to the fire pit structure. ( Add 5 feet to that length for every 90-degree bend in the pipe length.) The row across the top represents the possible gas pipe diameters, i.e., 1/2 “, 3/4” etc.

Starting in the left column, select the overall length of the gas pipe required. ( if you figure falls between two of the options always go the longer distance ). Let’s say you need 110 feet of gas pipe, you would select the 125 feet figure.

Now we look to the right along the line of figures that will provide our 75,000 BTU unit with enough gas. The first figure we find is 28, that is 28,000 BTU, so that is not enough for our 75,000 BTU unit. The next figure to the right is 60 that represents 60,000 BTU, which is still not enough for our 75,000 BTU unit, so continuing moving to the right, the next figure is 117 equalling 117,000 BTU, and that is more than enough for your 75,000 BTU requirement. Now, look up to the top row of the chart above the 117 figure, and that shows that you will need a 1″ diameter gas pipe.

The calculations are different for Natural Gas and Propane, so be sure to use the right charts.

Gas Hard Piping Size For Fire Pits Tables

Natural Gas Pipe Size Chart

PIPE LENGTH (feet) 1/2” 3/4” 1” 1 - 1/4” 1 - 1/2” 2” 2 - 1/2” 3” 4”
10 108 230 387 793 1237 2259 3640 6434 -
20 75 160 280 569 877 1610 2613 5236 9521
30 61 129 224 471 719 1335 2165 4107 7859
40 52 110 196 401 635 1143 1867 3258 6795
50 46 98 177 364 560 1041 1680 2936 6142
60 42 89 159 336 513 957 1559 2684 5647
70 38 82 149 317 476 896 1447 2492 5250
80 36 76 140 239 443 840 1353 2315 4900
90 33 71 133 275 420 793 1288 2203 4667
100 32 68 126 266 411 775 1246 2128 4518
125 28 60 117 243 369 700 1143 1904 4065
150 25 54 105 215 327 625 1008 1689 3645
175 23 50 93 196 303 583 993 1554 3370
200 22 47 84 182 280 541 877 1437 3160
300 17 37 70 145 224 439 686 1139 2539
Natural Gas (NG) flow is given in thousands of BTU/hr. One cubic foot of NG gas – 1000 BTU.
Nominal pressure at the burner for Natural Gas is 3.5” of water column. (Typical machine supply 5” – 7”).

Pipe length must include additional length for all fittings. Add approximately 5 feet of pipe per fitting.

Natural Gas Example: A machine with a burner that requires 440,000 BTU would need a 1 – 1/4” pipe for a 20’ long run.

Propane Gas Pipe Size Chart

PIPE LENGTH (feet) 1/2” 3/4” 1” 1 - 1/4” 1 - 1/2” 2” 2 - 1/2” 3” 4”
10 275 567 1071 2205 3307 6221 10140 17990 35710
20 189 393 732 1496 2299 4331 7046 12510 25520
30 152 315 590 1212 1858 3465 5695 10110 20620
40 129 267 504 1039 1559 2992 4778 8481 17300
50 114 237 448 913 1417 2646 4343 7708 15730
60 103 217 409 834 1275 2394 3908 6936 14150
70 89 185 346 724 1086 2047 3329 5908 12050
80 78 162 307 630 976 1811 2991 5309 10830
90 69 146 275 567 866 1606 2654 4711 9613
100 63 132 252 511 787 1496 2412 4281 8736
125 54 112 209 439 665 1282 2083 3618 7382
150 48 100 185 390 590 1138 1808 3210 6549
175 43 90 168 353 534 1030 1637 2905 5927
200 40 83 155 325 491 947 1505 2671 5450
300 37 77 144 303 458 887 1404 2492 5084

Liquid Propane (LP) flow is given in thousands of BTU/hr. One cubic foot of NG gas – 2516 BTU

This chart refers to low pressure LP, after regulation, standard nominal pressure at the burner for Liquid Propane Gas is 11” of water column
Pipe length must include additional length for all fittings. Add approximately 5 feet of pipe per fitting.

Liquid Propane Example: A machine with a burner that requires 440,000 BTU would need a 1” pipe for a 20’ long run.

NOTE: The Gas Hard Piping Size For Fire Pits charts above list the specific pipe sizes required for the amount of BTU’s for a new gas line installations. If you are using an existing gas line you must take into consideration the existing gas line capacities to ensure you will have proper pressure. This chart is for reference only, we recommend you consult with a Licensed Plumber/Gas Fitter or NFPA54 (National Fuel Gas Code 72 – current edition) for more details.