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Wobbe index
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<h2 id="wobbe-index-of-common-fuel-gaseswobbe-index-and-fuel-gases">Wobbe index of common fuel gases<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></h2> <p>Note that these Wobbe numbers below are not calculated at 15 °C and so are not correct according to ISO 13443, see <a href="/facts/Standard_temperature_and_pressure/JhJv9KFJ">Standard temperature and pressure</a>. </p> <table><tbody><tr><th>Fuel gas</th><th>Upper index<a href="/facts/Calorie/ntNMPx65">kcal</a>/Nm³</th><th>Lower indexkcal/<a href="/facts/Standard_temperature_and_pressure/JhJv9KFJ">Nm³</a></th><th>Upper index<a href="/facts/Megajoule/9ndq9jD2">MJ</a>/m³</th><th>Lower indexMJ/m³</th></tr><tr><td><a href="/facts/Hydrogen/BoYHjl0J">Hydrogen</a></td><td>11,528</td><td>9,715</td><td>48.23</td><td>40.65</td></tr><tr><td><a href="/facts/Methane/kBHneYnh">Methane</a></td><td>12,735</td><td>11,452</td><td>53.28</td><td>47.91</td></tr><tr><td><a href="/facts/Ethane/BGCzc6yh">Ethane</a></td><td>16,298</td><td>14,931</td><td>68.19</td><td>62.47</td></tr><tr><td><a href="/facts/Ethylene/QMNBYLYn">Ethylene</a></td><td>15,253</td><td>14,344</td><td>63.82</td><td>60.01</td></tr><tr><td><a href="/facts/Natural_gas/9MYQ7NAP">Natural gas</a></td><td>12,837</td><td>11,597</td><td>53.71</td><td>48.52</td></tr><tr><td><a href="/facts/Propane/E0b23KGh">Propane</a></td><td>19,376</td><td>17,817</td><td>81.07</td><td>74.54</td></tr><tr><td><a href="/facts/Propylene/5eLDmPvm">Propylene</a></td><td>18,413</td><td>17,180</td><td>77.04</td><td>71.88</td></tr><tr><td><a href="/facts/N-butane/InIHpYlY">n-butane</a></td><td>22,066</td><td>20,336</td><td>92.32</td><td>85.08</td></tr><tr><td><a href="/facts/Iso-butane/Bd8H7rsH">Iso-butane</a></td><td>21,980</td><td>20,247</td><td>91.96</td><td>84.71</td></tr><tr><td><a href="/facts/Butylene-1/6JdB9n0U">Butylene-1</a></td><td>21,142</td><td>19,728</td><td>88.46</td><td>82.54</td></tr><tr><td><a href="/facts/Liquefied_petroleum_gas/bw6trakm">LPG</a></td><td>20,755</td><td>19,106</td><td>86.84</td><td>79.94</td></tr><tr><td><a href="/facts/Acetylene/yaDh6cmJ">Acetylene</a></td><td>14,655</td><td>14,141</td><td>61.32</td><td>59.16</td></tr><tr><td><a href="/facts/Carbon_monoxide/CKuLtEMJ">Carbon monoxide</a></td><td>3,060</td><td>3,060</td><td>12.80</td><td>12.80</td></tr></tbody></table> Note: 1 <a href="/facts/Joule/9ndq9jD2">Joule</a> = 2.3901×10−4 <a href="/facts/Calorie/ntNMPx65">kcal</a>. <h2 id="usage">Usage</h2> <p>The Wobbe index is expressed in <a href="/facts/Megajoule/9ndq9jD2">MJ</a>/<a href="/facts/Standard_temperature_and_pressure/JhJv9KFJ">Nm³</a> (where 'Nm³' indicates'm³ in Normal conditions), or sometimes in <a href="/facts/British_Thermal_Unit/GwIjRAPz">BTU</a>/<a href="/facts/Standard_cubic_foot/vK9AzNT3">scf</a>. In the case of natural gas (<a href="/facts/Molar_mass/m2laJErl">molar mass</a> 17 g/mol), the typical heating value is around 39 MJ/Nm³ (1,050 BTU/scf) and the specific gravity is approximately 0.59, giving a typical Wobbe index of 51 MJ/Nm³ (1,367 BTU/scf). </p><p>There are three ranges or "families" of fuel gases that have been internationally agreed based on Wobbe index. Family 1 covers manufactured gases, family 2 covers natural gases (with high and low ranges) and family 3 covers liquefied petroleum gas (<a href="/facts/Liquefied_petroleum_gas/bw6trakm">LPG</a>). Combustion equipment is typically designed to burn a fuel gas within a particular family: hydrogen-rich town gas, natural gas or LPG. </p> <table><tbody><tr><th>Family</th><th>Type of gas</th><th>Wobbe index range (MJ/<a href="/facts/Standard_temperature_and_pressure/JhJv9KFJ">Nm3</a>)</th><th>Wobbe number range<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></th></tr><tr><td>1</td><td><a href="/facts/Town_gas/ekdg4VuE">Town gas</a> / <a href="/facts/Syngas/VfslxkIN">Syngas</a></td><td>22.5 – 30.0</td><td>24.0 – 29.0</td></tr><tr><td>2 L</td><td><a href="/facts/Natural_Gas/9MYQ7NAP">Natural</a></td><td>39.0 – 45.0</td><td></td></tr><tr><td>2 H</td><td></td><td>45.5 – 55.0</td><td>48.0 – 53.0</td></tr><tr><td>3</td><td><a href="/facts/Liquefied_petroleum_gas/bw6trakm">LPG</a></td><td>73.5 – 87.5</td><td>72.0 – 87.0</td></tr></tbody></table> <p>Other flame characteristics and composition limits may determine the acceptability of the replacement gas, e.g. <a href="/facts/Flame_speed/qBtqHBQs">flame speed</a>, "yellow tipping" due to incomplete combustion, sulfur content, <a href="/facts/Oxygen/acyn6o8r">oxygen</a> content, etc. </p> <h2 id="limitations">Limitations</h2> <p>In spite of its usefulness, Wobbe index alone is not a good indicator of the interchangeability of two or more gases, or mixtures of them. It is necessary to bear in mind other criteria while determining the plenty substitution of a fuel by other, different of the one used to adjust the burning system.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <ul><li><a href="http://www.documentation.emersonprocess.com/groups/public/documents/application_notes-tech._briefs/d301334x012.pdf?&xBusinessUnit=Remote%20Automation%20Solutions">"The Wobbe Index and Natural Gas Interchangeability"</a> (PDF). Emerson Process Management. 2007-07-30.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Treloar, R.D. (2005). Gas Installation Technology. Blackwell. p. 24. ISBN 978-1-4051-1880-4. <a href="978-1-4051-1880-4" target="_blank">978-1-4051-1880-4</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Bio Gas max" (PDF). Archived from the original (PDF) on 2015-09-23. Retrieved 2012-09-07. <a href="https://web.archive.org/web/20150923190029/http://www.biogasmax.eu/media/d3_3v2biogasmax_iwes_v2f_nov2010__052078600_1109_10022011.pdf" target="_blank">https://web.archive.org/web/20150923190029/http://www.biogasmax.eu/media/d3_3v2biogasmax_iwes_v2f_nov2010__052078600_1109_10022011.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Ingemar Gunnarsson <a href="http://www.sgc.se/gasification2011/Resources/Ingemar_Gunnarsson.pdf" target="_blank">http://www.sgc.se/gasification2011/Resources/Ingemar_Gunnarsson.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"American Gas Association" (PDF). Archived from the original (PDF) on 2021-12-29. Retrieved 2022-03-01. <a href="https://web.archive.org/web/20211229225516/https://www.aga.org/sites/default/files/legacy-assets/SiteCollectionDocuments/KnowledgeCenter/OpsEng/CodesStandards/0604GASINTERCHANGEABILITYSTAFFPAPER.pdf" target="_blank">https://web.archive.org/web/20211229225516/https://www.aga.org/sites/default/files/legacy-assets/SiteCollectionDocuments/KnowledgeCenter/OpsEng/CodesStandards/0604GASINTERCHANGEABILITYSTAFFPAPER.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Wobbe Index and Fuel Gases <a href="http://www.engineeringtoolbox.com/wobbe-index-d_421.html" target="_blank">http://www.engineeringtoolbox.com/wobbe-index-d_421.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Treloar, R.D. (2005). Gas Installation Technology. Blackwell. p. 24. ISBN 978-1-4051-1880-4. <a href="978-1-4051-1880-4" target="_blank">978-1-4051-1880-4</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Flórez-Orrego, Daniel, Escola Politécnica da USP. "Fuel Gas Interchangeability". Retrieved 8 Sep 2012.{{cite web}}: CS1 maint: multiple names: authors list (link) <a href="https://unalmed.academia.edu/DanielFl%C3%B3rezOrrego/Papers/1913409/Intercambiabilidad_de_gases_combustibles_Fuel_Gas_Interchangeability_Intercambiabilidade_dos_gases_combustiveis/" target="_blank">https://unalmed.academia.edu/DanielFl%C3%B3rezOrrego/Papers/1913409/Intercambiabilidad_de_gases_combustibles_Fuel_Gas_Interchangeability_Intercambiabilidade_dos_gases_combustiveis/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> </ol>